Index: stable/10/sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c =================================================================== --- stable/10/sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c (revision 272874) +++ stable/10/sys/cddl/compat/opensolaris/kern/opensolaris_kmem.c (revision 272875) @@ -1,281 +1,274 @@ /*- * Copyright (c) 2006-2007 Pawel Jakub Dawidek * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #ifdef KMEM_DEBUG #include #include #endif #ifdef _KERNEL MALLOC_DEFINE(M_SOLARIS, "solaris", "Solaris"); #else #define malloc(size, type, flags) malloc(size) #define free(addr, type) free(addr) #endif #ifdef KMEM_DEBUG struct kmem_item { struct stack stack; LIST_ENTRY(kmem_item) next; }; static LIST_HEAD(, kmem_item) kmem_items; static struct mtx kmem_items_mtx; MTX_SYSINIT(kmem_items_mtx, &kmem_items_mtx, "kmem_items", MTX_DEF); #endif /* KMEM_DEBUG */ #include void * zfs_kmem_alloc(size_t size, int kmflags) { void *p; #ifdef KMEM_DEBUG struct kmem_item *i; size += sizeof(struct kmem_item); #endif p = malloc(size, M_SOLARIS, kmflags); #ifndef _KERNEL if (kmflags & KM_SLEEP) assert(p != NULL); #endif #ifdef KMEM_DEBUG if (p != NULL) { i = p; p = (u_char *)p + sizeof(struct kmem_item); stack_save(&i->stack); mtx_lock(&kmem_items_mtx); LIST_INSERT_HEAD(&kmem_items, i, next); mtx_unlock(&kmem_items_mtx); } #endif return (p); } void zfs_kmem_free(void *buf, size_t size __unused) { #ifdef KMEM_DEBUG if (buf == NULL) { printf("%s: attempt to free NULL\n", __func__); return; } struct kmem_item *i; buf = (u_char *)buf - sizeof(struct kmem_item); mtx_lock(&kmem_items_mtx); LIST_FOREACH(i, &kmem_items, next) { if (i == buf) break; } ASSERT(i != NULL); LIST_REMOVE(i, next); mtx_unlock(&kmem_items_mtx); #endif free(buf, M_SOLARIS); } static uint64_t kmem_size_val; static void kmem_size_init(void *unused __unused) { kmem_size_val = (uint64_t)cnt.v_page_count * PAGE_SIZE; if (kmem_size_val > vm_kmem_size) kmem_size_val = vm_kmem_size; } SYSINIT(kmem_size_init, SI_SUB_KMEM, SI_ORDER_ANY, kmem_size_init, NULL); uint64_t kmem_size(void) { return (kmem_size_val); } -uint64_t -kmem_used(void) -{ - - return (vmem_size(kmem_arena, VMEM_ALLOC)); -} - static int kmem_std_constructor(void *mem, int size __unused, void *private, int flags) { struct kmem_cache *cache = private; return (cache->kc_constructor(mem, cache->kc_private, flags)); } static void kmem_std_destructor(void *mem, int size __unused, void *private) { struct kmem_cache *cache = private; cache->kc_destructor(mem, cache->kc_private); } kmem_cache_t * kmem_cache_create(char *name, size_t bufsize, size_t align, int (*constructor)(void *, void *, int), void (*destructor)(void *, void *), void (*reclaim)(void *) __unused, void *private, vmem_t *vmp, int cflags) { kmem_cache_t *cache; ASSERT(vmp == NULL); cache = kmem_alloc(sizeof(*cache), KM_SLEEP); strlcpy(cache->kc_name, name, sizeof(cache->kc_name)); cache->kc_constructor = constructor; cache->kc_destructor = destructor; cache->kc_private = private; #if defined(_KERNEL) && !defined(KMEM_DEBUG) cache->kc_zone = uma_zcreate(cache->kc_name, bufsize, constructor != NULL ? kmem_std_constructor : NULL, destructor != NULL ? kmem_std_destructor : NULL, NULL, NULL, align > 0 ? align - 1 : 0, cflags); #else cache->kc_size = bufsize; #endif return (cache); } void kmem_cache_destroy(kmem_cache_t *cache) { #if defined(_KERNEL) && !defined(KMEM_DEBUG) uma_zdestroy(cache->kc_zone); #endif kmem_free(cache, sizeof(*cache)); } void * kmem_cache_alloc(kmem_cache_t *cache, int flags) { #if defined(_KERNEL) && !defined(KMEM_DEBUG) return (uma_zalloc_arg(cache->kc_zone, cache, flags)); #else void *p; p = kmem_alloc(cache->kc_size, flags); if (p != NULL && cache->kc_constructor != NULL) kmem_std_constructor(p, cache->kc_size, cache, flags); return (p); #endif } void kmem_cache_free(kmem_cache_t *cache, void *buf) { #if defined(_KERNEL) && !defined(KMEM_DEBUG) uma_zfree_arg(cache->kc_zone, buf, cache); #else if (cache->kc_destructor != NULL) kmem_std_destructor(buf, cache->kc_size, cache); kmem_free(buf, cache->kc_size); #endif } #ifdef _KERNEL void kmem_cache_reap_now(kmem_cache_t *cache) { #ifndef KMEM_DEBUG zone_drain(cache->kc_zone); #endif } void kmem_reap(void) { uma_reclaim(); } #else void kmem_cache_reap_now(kmem_cache_t *cache __unused) { } void kmem_reap(void) { } #endif int kmem_debugging(void) { return (0); } void * calloc(size_t n, size_t s) { return (kmem_zalloc(n * s, KM_NOSLEEP)); } #ifdef KMEM_DEBUG void kmem_show(void *); void kmem_show(void *dummy __unused) { struct kmem_item *i; mtx_lock(&kmem_items_mtx); if (LIST_EMPTY(&kmem_items)) printf("KMEM_DEBUG: No leaked elements.\n"); else { printf("KMEM_DEBUG: Leaked elements:\n\n"); LIST_FOREACH(i, &kmem_items, next) { printf("address=%p\n", i); stack_print_ddb(&i->stack); printf("\n"); } } mtx_unlock(&kmem_items_mtx); } SYSUNINIT(sol_kmem, SI_SUB_CPU, SI_ORDER_FIRST, kmem_show, NULL); #endif /* KMEM_DEBUG */ Index: stable/10/sys/cddl/compat/opensolaris/sys/kmem.h =================================================================== --- stable/10/sys/cddl/compat/opensolaris/sys/kmem.h (revision 272874) +++ stable/10/sys/cddl/compat/opensolaris/sys/kmem.h (revision 272875) @@ -1,87 +1,89 @@ /*- * Copyright (c) 2007 Pawel Jakub Dawidek * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD$ */ #ifndef _OPENSOLARIS_SYS_KMEM_H_ #define _OPENSOLARIS_SYS_KMEM_H_ #include #include #include #include #include #include #include MALLOC_DECLARE(M_SOLARIS); #define POINTER_IS_VALID(p) (!((uintptr_t)(p) & 0x3)) #define POINTER_INVALIDATE(pp) (*(pp) = (void *)((uintptr_t)(*(pp)) | 0x1)) #define KM_SLEEP M_WAITOK #define KM_PUSHPAGE M_WAITOK #define KM_NOSLEEP M_NOWAIT #define KM_NODEBUG M_NODUMP #define KM_NORMALPRI 0 #define KMC_NODEBUG UMA_ZONE_NODUMP #define KMC_NOTOUCH 0 typedef struct kmem_cache { char kc_name[32]; #if defined(_KERNEL) && !defined(KMEM_DEBUG) uma_zone_t kc_zone; #else size_t kc_size; #endif int (*kc_constructor)(void *, void *, int); void (*kc_destructor)(void *, void *); void *kc_private; } kmem_cache_t; void *zfs_kmem_alloc(size_t size, int kmflags); void zfs_kmem_free(void *buf, size_t size); uint64_t kmem_size(void); -uint64_t kmem_used(void); kmem_cache_t *kmem_cache_create(char *name, size_t bufsize, size_t align, int (*constructor)(void *, void *, int), void (*destructor)(void *, void *), void (*reclaim)(void *) __unused, void *private, vmem_t *vmp, int cflags); void kmem_cache_destroy(kmem_cache_t *cache); void *kmem_cache_alloc(kmem_cache_t *cache, int flags); void kmem_cache_free(kmem_cache_t *cache, void *buf); void kmem_cache_reap_now(kmem_cache_t *cache); void kmem_reap(void); int kmem_debugging(void); void *calloc(size_t n, size_t s); +#define freemem (cnt.v_free_count + cnt.v_cache_count) +#define minfree cnt.v_free_min +#define heap_arena kmem_arena #define kmem_alloc(size, kmflags) zfs_kmem_alloc((size), (kmflags)) #define kmem_zalloc(size, kmflags) zfs_kmem_alloc((size), (kmflags) | M_ZERO) #define kmem_free(buf, size) zfs_kmem_free((buf), (size)) #define kmem_cache_set_move(cache, movefunc) do { } while (0) #endif /* _OPENSOLARIS_SYS_KMEM_H_ */ Index: stable/10/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c =================================================================== --- stable/10/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c (revision 272874) +++ stable/10/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c (revision 272875) @@ -1,5599 +1,5681 @@ /* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2011, 2014 by Delphix. All rights reserved. * Copyright (c) 2014 by Saso Kiselkov. All rights reserved. * Copyright 2014 Nexenta Systems, Inc. All rights reserved. */ /* * DVA-based Adjustable Replacement Cache * * While much of the theory of operation used here is * based on the self-tuning, low overhead replacement cache * presented by Megiddo and Modha at FAST 2003, there are some * significant differences: * * 1. The Megiddo and Modha model assumes any page is evictable. * Pages in its cache cannot be "locked" into memory. This makes * the eviction algorithm simple: evict the last page in the list. * This also make the performance characteristics easy to reason * about. Our cache is not so simple. At any given moment, some * subset of the blocks in the cache are un-evictable because we * have handed out a reference to them. Blocks are only evictable * when there are no external references active. This makes * eviction far more problematic: we choose to evict the evictable * blocks that are the "lowest" in the list. * * There are times when it is not possible to evict the requested * space. In these circumstances we are unable to adjust the cache * size. To prevent the cache growing unbounded at these times we * implement a "cache throttle" that slows the flow of new data * into the cache until we can make space available. * * 2. The Megiddo and Modha model assumes a fixed cache size. * Pages are evicted when the cache is full and there is a cache * miss. Our model has a variable sized cache. It grows with * high use, but also tries to react to memory pressure from the * operating system: decreasing its size when system memory is * tight. * * 3. The Megiddo and Modha model assumes a fixed page size. All * elements of the cache are therefore exactly the same size. So * when adjusting the cache size following a cache miss, its simply * a matter of choosing a single page to evict. In our model, we * have variable sized cache blocks (rangeing from 512 bytes to * 128K bytes). We therefore choose a set of blocks to evict to make * space for a cache miss that approximates as closely as possible * the space used by the new block. * * See also: "ARC: A Self-Tuning, Low Overhead Replacement Cache" * by N. Megiddo & D. Modha, FAST 2003 */ /* * The locking model: * * A new reference to a cache buffer can be obtained in two * ways: 1) via a hash table lookup using the DVA as a key, * or 2) via one of the ARC lists. The arc_read() interface * uses method 1, while the internal arc algorithms for * adjusting the cache use method 2. We therefore provide two * types of locks: 1) the hash table lock array, and 2) the * arc list locks. * * Buffers do not have their own mutexs, rather they rely on the * hash table mutexs for the bulk of their protection (i.e. most * fields in the arc_buf_hdr_t are protected by these mutexs). * * buf_hash_find() returns the appropriate mutex (held) when it * locates the requested buffer in the hash table. It returns * NULL for the mutex if the buffer was not in the table. * * buf_hash_remove() expects the appropriate hash mutex to be * already held before it is invoked. * * Each arc state also has a mutex which is used to protect the * buffer list associated with the state. When attempting to * obtain a hash table lock while holding an arc list lock you * must use: mutex_tryenter() to avoid deadlock. Also note that * the active state mutex must be held before the ghost state mutex. * * Arc buffers may have an associated eviction callback function. * This function will be invoked prior to removing the buffer (e.g. * in arc_do_user_evicts()). Note however that the data associated * with the buffer may be evicted prior to the callback. The callback * must be made with *no locks held* (to prevent deadlock). Additionally, * the users of callbacks must ensure that their private data is * protected from simultaneous callbacks from arc_clear_callback() * and arc_do_user_evicts(). * * Note that the majority of the performance stats are manipulated * with atomic operations. * * The L2ARC uses the l2arc_buflist_mtx global mutex for the following: * * - L2ARC buflist creation * - L2ARC buflist eviction * - L2ARC write completion, which walks L2ARC buflists * - ARC header destruction, as it removes from L2ARC buflists * - ARC header release, as it removes from L2ARC buflists */ #include #include #include #include #include #include #include #include #include #ifdef _KERNEL #include #endif #include #include #include #include #include #include +#include #ifdef illumos #ifndef _KERNEL /* set with ZFS_DEBUG=watch, to enable watchpoints on frozen buffers */ boolean_t arc_watch = B_FALSE; int arc_procfd; #endif #endif /* illumos */ static kmutex_t arc_reclaim_thr_lock; static kcondvar_t arc_reclaim_thr_cv; /* used to signal reclaim thr */ static uint8_t arc_thread_exit; #define ARC_REDUCE_DNLC_PERCENT 3 uint_t arc_reduce_dnlc_percent = ARC_REDUCE_DNLC_PERCENT; typedef enum arc_reclaim_strategy { ARC_RECLAIM_AGGR, /* Aggressive reclaim strategy */ ARC_RECLAIM_CONS /* Conservative reclaim strategy */ } arc_reclaim_strategy_t; /* * The number of iterations through arc_evict_*() before we * drop & reacquire the lock. */ int arc_evict_iterations = 100; /* number of seconds before growing cache again */ static int arc_grow_retry = 60; /* shift of arc_c for calculating both min and max arc_p */ static int arc_p_min_shift = 4; /* log2(fraction of arc to reclaim) */ static int arc_shrink_shift = 5; /* * minimum lifespan of a prefetch block in clock ticks * (initialized in arc_init()) */ static int arc_min_prefetch_lifespan; /* * If this percent of memory is free, don't throttle. */ int arc_lotsfree_percent = 10; static int arc_dead; extern int zfs_prefetch_disable; /* * The arc has filled available memory and has now warmed up. */ static boolean_t arc_warm; -/* - * These tunables are for performance analysis. - */ uint64_t zfs_arc_max; uint64_t zfs_arc_min; uint64_t zfs_arc_meta_limit = 0; int zfs_arc_grow_retry = 0; int zfs_arc_shrink_shift = 0; int zfs_arc_p_min_shift = 0; int zfs_disable_dup_eviction = 0; uint64_t zfs_arc_average_blocksize = 8 * 1024; /* 8KB */ +u_int zfs_arc_free_target = 0; +static int sysctl_vfs_zfs_arc_free_target(SYSCTL_HANDLER_ARGS); + +#ifdef _KERNEL +static void +arc_free_target_init(void *unused __unused) +{ + + zfs_arc_free_target = vm_pageout_wakeup_thresh; +} +SYSINIT(arc_free_target_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_ANY, + arc_free_target_init, NULL); + TUNABLE_QUAD("vfs.zfs.arc_max", &zfs_arc_max); TUNABLE_QUAD("vfs.zfs.arc_min", &zfs_arc_min); TUNABLE_QUAD("vfs.zfs.arc_meta_limit", &zfs_arc_meta_limit); TUNABLE_QUAD("vfs.zfs.arc_average_blocksize", &zfs_arc_average_blocksize); SYSCTL_DECL(_vfs_zfs); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, arc_max, CTLFLAG_RDTUN, &zfs_arc_max, 0, "Maximum ARC size"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, arc_min, CTLFLAG_RDTUN, &zfs_arc_min, 0, "Minimum ARC size"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, arc_average_blocksize, CTLFLAG_RDTUN, &zfs_arc_average_blocksize, 0, "ARC average blocksize"); +/* + * We don't have a tunable for arc_free_target due to the dependency on + * pagedaemon initialisation. + */ +SYSCTL_PROC(_vfs_zfs, OID_AUTO, arc_free_target, + CTLTYPE_UINT | CTLFLAG_MPSAFE | CTLFLAG_RW, 0, sizeof(u_int), + sysctl_vfs_zfs_arc_free_target, "IU", + "Desired number of free pages below which ARC triggers reclaim"); +static int +sysctl_vfs_zfs_arc_free_target(SYSCTL_HANDLER_ARGS) +{ + u_int val; + int err; + + val = zfs_arc_free_target; + err = sysctl_handle_int(oidp, &val, 0, req); + if (err != 0 || req->newptr == NULL) + return (err); + + if (val < minfree) + return (EINVAL); + if (val > cnt.v_page_count) + return (EINVAL); + + zfs_arc_free_target = val; + + return (0); +} +#endif + /* * Note that buffers can be in one of 6 states: * ARC_anon - anonymous (discussed below) * ARC_mru - recently used, currently cached * ARC_mru_ghost - recentely used, no longer in cache * ARC_mfu - frequently used, currently cached * ARC_mfu_ghost - frequently used, no longer in cache * ARC_l2c_only - exists in L2ARC but not other states * When there are no active references to the buffer, they are * are linked onto a list in one of these arc states. These are * the only buffers that can be evicted or deleted. Within each * state there are multiple lists, one for meta-data and one for * non-meta-data. Meta-data (indirect blocks, blocks of dnodes, * etc.) is tracked separately so that it can be managed more * explicitly: favored over data, limited explicitly. * * Anonymous buffers are buffers that are not associated with * a DVA. These are buffers that hold dirty block copies * before they are written to stable storage. By definition, * they are "ref'd" and are considered part of arc_mru * that cannot be freed. Generally, they will aquire a DVA * as they are written and migrate onto the arc_mru list. * * The ARC_l2c_only state is for buffers that are in the second * level ARC but no longer in any of the ARC_m* lists. The second * level ARC itself may also contain buffers that are in any of * the ARC_m* states - meaning that a buffer can exist in two * places. The reason for the ARC_l2c_only state is to keep the * buffer header in the hash table, so that reads that hit the * second level ARC benefit from these fast lookups. */ #define ARCS_LOCK_PAD CACHE_LINE_SIZE struct arcs_lock { kmutex_t arcs_lock; #ifdef _KERNEL unsigned char pad[(ARCS_LOCK_PAD - sizeof (kmutex_t))]; #endif }; /* * must be power of two for mask use to work * */ #define ARC_BUFC_NUMDATALISTS 16 #define ARC_BUFC_NUMMETADATALISTS 16 #define ARC_BUFC_NUMLISTS (ARC_BUFC_NUMMETADATALISTS + ARC_BUFC_NUMDATALISTS) typedef struct arc_state { uint64_t arcs_lsize[ARC_BUFC_NUMTYPES]; /* amount of evictable data */ uint64_t arcs_size; /* total amount of data in this state */ list_t arcs_lists[ARC_BUFC_NUMLISTS]; /* list of evictable buffers */ struct arcs_lock arcs_locks[ARC_BUFC_NUMLISTS] __aligned(CACHE_LINE_SIZE); } arc_state_t; #define ARCS_LOCK(s, i) (&((s)->arcs_locks[(i)].arcs_lock)) /* The 6 states: */ static arc_state_t ARC_anon; static arc_state_t ARC_mru; static arc_state_t ARC_mru_ghost; static arc_state_t ARC_mfu; static arc_state_t ARC_mfu_ghost; static arc_state_t ARC_l2c_only; typedef struct arc_stats { kstat_named_t arcstat_hits; kstat_named_t arcstat_misses; kstat_named_t arcstat_demand_data_hits; kstat_named_t arcstat_demand_data_misses; kstat_named_t arcstat_demand_metadata_hits; kstat_named_t arcstat_demand_metadata_misses; kstat_named_t arcstat_prefetch_data_hits; kstat_named_t arcstat_prefetch_data_misses; kstat_named_t arcstat_prefetch_metadata_hits; kstat_named_t arcstat_prefetch_metadata_misses; kstat_named_t arcstat_mru_hits; kstat_named_t arcstat_mru_ghost_hits; kstat_named_t arcstat_mfu_hits; kstat_named_t arcstat_mfu_ghost_hits; kstat_named_t arcstat_allocated; kstat_named_t arcstat_deleted; kstat_named_t arcstat_stolen; kstat_named_t arcstat_recycle_miss; /* * Number of buffers that could not be evicted because the hash lock * was held by another thread. The lock may not necessarily be held * by something using the same buffer, since hash locks are shared * by multiple buffers. */ kstat_named_t arcstat_mutex_miss; /* * Number of buffers skipped because they have I/O in progress, are * indrect prefetch buffers that have not lived long enough, or are * not from the spa we're trying to evict from. */ kstat_named_t arcstat_evict_skip; kstat_named_t arcstat_evict_l2_cached; kstat_named_t arcstat_evict_l2_eligible; kstat_named_t arcstat_evict_l2_ineligible; kstat_named_t arcstat_hash_elements; kstat_named_t arcstat_hash_elements_max; kstat_named_t arcstat_hash_collisions; kstat_named_t arcstat_hash_chains; kstat_named_t arcstat_hash_chain_max; kstat_named_t arcstat_p; kstat_named_t arcstat_c; kstat_named_t arcstat_c_min; kstat_named_t arcstat_c_max; kstat_named_t arcstat_size; kstat_named_t arcstat_hdr_size; kstat_named_t arcstat_data_size; kstat_named_t arcstat_other_size; kstat_named_t arcstat_l2_hits; kstat_named_t arcstat_l2_misses; kstat_named_t arcstat_l2_feeds; kstat_named_t arcstat_l2_rw_clash; kstat_named_t arcstat_l2_read_bytes; kstat_named_t arcstat_l2_write_bytes; kstat_named_t arcstat_l2_writes_sent; kstat_named_t arcstat_l2_writes_done; kstat_named_t arcstat_l2_writes_error; kstat_named_t arcstat_l2_writes_hdr_miss; kstat_named_t arcstat_l2_evict_lock_retry; kstat_named_t arcstat_l2_evict_reading; kstat_named_t arcstat_l2_free_on_write; kstat_named_t arcstat_l2_abort_lowmem; kstat_named_t arcstat_l2_cksum_bad; kstat_named_t arcstat_l2_io_error; kstat_named_t arcstat_l2_size; kstat_named_t arcstat_l2_asize; kstat_named_t arcstat_l2_hdr_size; kstat_named_t arcstat_l2_compress_successes; kstat_named_t arcstat_l2_compress_zeros; kstat_named_t arcstat_l2_compress_failures; kstat_named_t arcstat_l2_write_trylock_fail; kstat_named_t arcstat_l2_write_passed_headroom; kstat_named_t arcstat_l2_write_spa_mismatch; kstat_named_t arcstat_l2_write_in_l2; kstat_named_t arcstat_l2_write_hdr_io_in_progress; kstat_named_t arcstat_l2_write_not_cacheable; kstat_named_t arcstat_l2_write_full; kstat_named_t arcstat_l2_write_buffer_iter; kstat_named_t arcstat_l2_write_pios; kstat_named_t arcstat_l2_write_buffer_bytes_scanned; kstat_named_t arcstat_l2_write_buffer_list_iter; kstat_named_t arcstat_l2_write_buffer_list_null_iter; kstat_named_t arcstat_memory_throttle_count; kstat_named_t arcstat_duplicate_buffers; kstat_named_t arcstat_duplicate_buffers_size; kstat_named_t arcstat_duplicate_reads; } arc_stats_t; static arc_stats_t arc_stats = { { "hits", KSTAT_DATA_UINT64 }, { "misses", KSTAT_DATA_UINT64 }, { "demand_data_hits", KSTAT_DATA_UINT64 }, { "demand_data_misses", KSTAT_DATA_UINT64 }, { "demand_metadata_hits", KSTAT_DATA_UINT64 }, { "demand_metadata_misses", KSTAT_DATA_UINT64 }, { "prefetch_data_hits", KSTAT_DATA_UINT64 }, { "prefetch_data_misses", KSTAT_DATA_UINT64 }, { "prefetch_metadata_hits", KSTAT_DATA_UINT64 }, { "prefetch_metadata_misses", KSTAT_DATA_UINT64 }, { "mru_hits", KSTAT_DATA_UINT64 }, { "mru_ghost_hits", KSTAT_DATA_UINT64 }, { "mfu_hits", KSTAT_DATA_UINT64 }, { "mfu_ghost_hits", KSTAT_DATA_UINT64 }, { "allocated", KSTAT_DATA_UINT64 }, { "deleted", KSTAT_DATA_UINT64 }, { "stolen", KSTAT_DATA_UINT64 }, { "recycle_miss", KSTAT_DATA_UINT64 }, { "mutex_miss", KSTAT_DATA_UINT64 }, { "evict_skip", KSTAT_DATA_UINT64 }, { "evict_l2_cached", KSTAT_DATA_UINT64 }, { "evict_l2_eligible", KSTAT_DATA_UINT64 }, { "evict_l2_ineligible", KSTAT_DATA_UINT64 }, { "hash_elements", KSTAT_DATA_UINT64 }, { "hash_elements_max", KSTAT_DATA_UINT64 }, { "hash_collisions", KSTAT_DATA_UINT64 }, { "hash_chains", KSTAT_DATA_UINT64 }, { "hash_chain_max", KSTAT_DATA_UINT64 }, { "p", KSTAT_DATA_UINT64 }, { "c", KSTAT_DATA_UINT64 }, { "c_min", KSTAT_DATA_UINT64 }, { "c_max", KSTAT_DATA_UINT64 }, { "size", KSTAT_DATA_UINT64 }, { "hdr_size", KSTAT_DATA_UINT64 }, { "data_size", KSTAT_DATA_UINT64 }, { "other_size", KSTAT_DATA_UINT64 }, { "l2_hits", KSTAT_DATA_UINT64 }, { "l2_misses", KSTAT_DATA_UINT64 }, { "l2_feeds", KSTAT_DATA_UINT64 }, { "l2_rw_clash", KSTAT_DATA_UINT64 }, { "l2_read_bytes", KSTAT_DATA_UINT64 }, { "l2_write_bytes", KSTAT_DATA_UINT64 }, { "l2_writes_sent", KSTAT_DATA_UINT64 }, { "l2_writes_done", KSTAT_DATA_UINT64 }, { "l2_writes_error", KSTAT_DATA_UINT64 }, { "l2_writes_hdr_miss", KSTAT_DATA_UINT64 }, { "l2_evict_lock_retry", KSTAT_DATA_UINT64 }, { "l2_evict_reading", KSTAT_DATA_UINT64 }, { "l2_free_on_write", KSTAT_DATA_UINT64 }, { "l2_abort_lowmem", KSTAT_DATA_UINT64 }, { "l2_cksum_bad", KSTAT_DATA_UINT64 }, { "l2_io_error", KSTAT_DATA_UINT64 }, { "l2_size", KSTAT_DATA_UINT64 }, { "l2_asize", KSTAT_DATA_UINT64 }, { "l2_hdr_size", KSTAT_DATA_UINT64 }, { "l2_compress_successes", KSTAT_DATA_UINT64 }, { "l2_compress_zeros", KSTAT_DATA_UINT64 }, { "l2_compress_failures", KSTAT_DATA_UINT64 }, { "l2_write_trylock_fail", KSTAT_DATA_UINT64 }, { "l2_write_passed_headroom", KSTAT_DATA_UINT64 }, { "l2_write_spa_mismatch", KSTAT_DATA_UINT64 }, { "l2_write_in_l2", KSTAT_DATA_UINT64 }, { "l2_write_io_in_progress", KSTAT_DATA_UINT64 }, { "l2_write_not_cacheable", KSTAT_DATA_UINT64 }, { "l2_write_full", KSTAT_DATA_UINT64 }, { "l2_write_buffer_iter", KSTAT_DATA_UINT64 }, { "l2_write_pios", KSTAT_DATA_UINT64 }, { "l2_write_buffer_bytes_scanned", KSTAT_DATA_UINT64 }, { "l2_write_buffer_list_iter", KSTAT_DATA_UINT64 }, { "l2_write_buffer_list_null_iter", KSTAT_DATA_UINT64 }, { "memory_throttle_count", KSTAT_DATA_UINT64 }, { "duplicate_buffers", KSTAT_DATA_UINT64 }, { "duplicate_buffers_size", KSTAT_DATA_UINT64 }, { "duplicate_reads", KSTAT_DATA_UINT64 } }; #define ARCSTAT(stat) (arc_stats.stat.value.ui64) #define ARCSTAT_INCR(stat, val) \ atomic_add_64(&arc_stats.stat.value.ui64, (val)) #define ARCSTAT_BUMP(stat) ARCSTAT_INCR(stat, 1) #define ARCSTAT_BUMPDOWN(stat) ARCSTAT_INCR(stat, -1) #define ARCSTAT_MAX(stat, val) { \ uint64_t m; \ while ((val) > (m = arc_stats.stat.value.ui64) && \ (m != atomic_cas_64(&arc_stats.stat.value.ui64, m, (val)))) \ continue; \ } #define ARCSTAT_MAXSTAT(stat) \ ARCSTAT_MAX(stat##_max, arc_stats.stat.value.ui64) /* * We define a macro to allow ARC hits/misses to be easily broken down by * two separate conditions, giving a total of four different subtypes for * each of hits and misses (so eight statistics total). */ #define ARCSTAT_CONDSTAT(cond1, stat1, notstat1, cond2, stat2, notstat2, stat) \ if (cond1) { \ if (cond2) { \ ARCSTAT_BUMP(arcstat_##stat1##_##stat2##_##stat); \ } else { \ ARCSTAT_BUMP(arcstat_##stat1##_##notstat2##_##stat); \ } \ } else { \ if (cond2) { \ ARCSTAT_BUMP(arcstat_##notstat1##_##stat2##_##stat); \ } else { \ ARCSTAT_BUMP(arcstat_##notstat1##_##notstat2##_##stat);\ } \ } kstat_t *arc_ksp; static arc_state_t *arc_anon; static arc_state_t *arc_mru; static arc_state_t *arc_mru_ghost; static arc_state_t *arc_mfu; static arc_state_t *arc_mfu_ghost; static arc_state_t *arc_l2c_only; /* * There are several ARC variables that are critical to export as kstats -- * but we don't want to have to grovel around in the kstat whenever we wish to * manipulate them. For these variables, we therefore define them to be in * terms of the statistic variable. This assures that we are not introducing * the possibility of inconsistency by having shadow copies of the variables, * while still allowing the code to be readable. */ #define arc_size ARCSTAT(arcstat_size) /* actual total arc size */ #define arc_p ARCSTAT(arcstat_p) /* target size of MRU */ #define arc_c ARCSTAT(arcstat_c) /* target size of cache */ #define arc_c_min ARCSTAT(arcstat_c_min) /* min target cache size */ #define arc_c_max ARCSTAT(arcstat_c_max) /* max target cache size */ #define L2ARC_IS_VALID_COMPRESS(_c_) \ ((_c_) == ZIO_COMPRESS_LZ4 || (_c_) == ZIO_COMPRESS_EMPTY) static int arc_no_grow; /* Don't try to grow cache size */ static uint64_t arc_tempreserve; static uint64_t arc_loaned_bytes; static uint64_t arc_meta_used; static uint64_t arc_meta_limit; static uint64_t arc_meta_max = 0; SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, arc_meta_used, CTLFLAG_RD, &arc_meta_used, 0, "ARC metadata used"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, arc_meta_limit, CTLFLAG_RW, &arc_meta_limit, 0, "ARC metadata limit"); typedef struct l2arc_buf_hdr l2arc_buf_hdr_t; typedef struct arc_callback arc_callback_t; struct arc_callback { void *acb_private; arc_done_func_t *acb_done; arc_buf_t *acb_buf; zio_t *acb_zio_dummy; arc_callback_t *acb_next; }; typedef struct arc_write_callback arc_write_callback_t; struct arc_write_callback { void *awcb_private; arc_done_func_t *awcb_ready; arc_done_func_t *awcb_physdone; arc_done_func_t *awcb_done; arc_buf_t *awcb_buf; }; struct arc_buf_hdr { /* protected by hash lock */ dva_t b_dva; uint64_t b_birth; uint64_t b_cksum0; kmutex_t b_freeze_lock; zio_cksum_t *b_freeze_cksum; void *b_thawed; arc_buf_hdr_t *b_hash_next; arc_buf_t *b_buf; uint32_t b_flags; uint32_t b_datacnt; arc_callback_t *b_acb; kcondvar_t b_cv; /* immutable */ arc_buf_contents_t b_type; uint64_t b_size; uint64_t b_spa; /* protected by arc state mutex */ arc_state_t *b_state; list_node_t b_arc_node; /* updated atomically */ clock_t b_arc_access; /* self protecting */ refcount_t b_refcnt; l2arc_buf_hdr_t *b_l2hdr; list_node_t b_l2node; }; static arc_buf_t *arc_eviction_list; static kmutex_t arc_eviction_mtx; static arc_buf_hdr_t arc_eviction_hdr; static void arc_get_data_buf(arc_buf_t *buf); static void arc_access(arc_buf_hdr_t *buf, kmutex_t *hash_lock); static int arc_evict_needed(arc_buf_contents_t type); static void arc_evict_ghost(arc_state_t *state, uint64_t spa, int64_t bytes); #ifdef illumos static void arc_buf_watch(arc_buf_t *buf); #endif /* illumos */ static boolean_t l2arc_write_eligible(uint64_t spa_guid, arc_buf_hdr_t *ab); #define GHOST_STATE(state) \ ((state) == arc_mru_ghost || (state) == arc_mfu_ghost || \ (state) == arc_l2c_only) /* * Private ARC flags. These flags are private ARC only flags that will show up * in b_flags in the arc_hdr_buf_t. Some flags are publicly declared, and can * be passed in as arc_flags in things like arc_read. However, these flags * should never be passed and should only be set by ARC code. When adding new * public flags, make sure not to smash the private ones. */ #define ARC_IN_HASH_TABLE (1 << 9) /* this buffer is hashed */ #define ARC_IO_IN_PROGRESS (1 << 10) /* I/O in progress for buf */ #define ARC_IO_ERROR (1 << 11) /* I/O failed for buf */ #define ARC_FREED_IN_READ (1 << 12) /* buf freed while in read */ #define ARC_BUF_AVAILABLE (1 << 13) /* block not in active use */ #define ARC_INDIRECT (1 << 14) /* this is an indirect block */ #define ARC_FREE_IN_PROGRESS (1 << 15) /* hdr about to be freed */ #define ARC_L2_WRITING (1 << 16) /* L2ARC write in progress */ #define ARC_L2_EVICTED (1 << 17) /* evicted during I/O */ #define ARC_L2_WRITE_HEAD (1 << 18) /* head of write list */ #define HDR_IN_HASH_TABLE(hdr) ((hdr)->b_flags & ARC_IN_HASH_TABLE) #define HDR_IO_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS) #define HDR_IO_ERROR(hdr) ((hdr)->b_flags & ARC_IO_ERROR) #define HDR_PREFETCH(hdr) ((hdr)->b_flags & ARC_PREFETCH) #define HDR_FREED_IN_READ(hdr) ((hdr)->b_flags & ARC_FREED_IN_READ) #define HDR_BUF_AVAILABLE(hdr) ((hdr)->b_flags & ARC_BUF_AVAILABLE) #define HDR_FREE_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_FREE_IN_PROGRESS) #define HDR_L2CACHE(hdr) ((hdr)->b_flags & ARC_L2CACHE) #define HDR_L2_READING(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS && \ (hdr)->b_l2hdr != NULL) #define HDR_L2_WRITING(hdr) ((hdr)->b_flags & ARC_L2_WRITING) #define HDR_L2_EVICTED(hdr) ((hdr)->b_flags & ARC_L2_EVICTED) #define HDR_L2_WRITE_HEAD(hdr) ((hdr)->b_flags & ARC_L2_WRITE_HEAD) /* * Other sizes */ #define HDR_SIZE ((int64_t)sizeof (arc_buf_hdr_t)) #define L2HDR_SIZE ((int64_t)sizeof (l2arc_buf_hdr_t)) /* * Hash table routines */ #define HT_LOCK_PAD CACHE_LINE_SIZE struct ht_lock { kmutex_t ht_lock; #ifdef _KERNEL unsigned char pad[(HT_LOCK_PAD - sizeof (kmutex_t))]; #endif }; #define BUF_LOCKS 256 typedef struct buf_hash_table { uint64_t ht_mask; arc_buf_hdr_t **ht_table; struct ht_lock ht_locks[BUF_LOCKS] __aligned(CACHE_LINE_SIZE); } buf_hash_table_t; static buf_hash_table_t buf_hash_table; #define BUF_HASH_INDEX(spa, dva, birth) \ (buf_hash(spa, dva, birth) & buf_hash_table.ht_mask) #define BUF_HASH_LOCK_NTRY(idx) (buf_hash_table.ht_locks[idx & (BUF_LOCKS-1)]) #define BUF_HASH_LOCK(idx) (&(BUF_HASH_LOCK_NTRY(idx).ht_lock)) #define HDR_LOCK(hdr) \ (BUF_HASH_LOCK(BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth))) uint64_t zfs_crc64_table[256]; /* * Level 2 ARC */ #define L2ARC_WRITE_SIZE (8 * 1024 * 1024) /* initial write max */ #define L2ARC_HEADROOM 2 /* num of writes */ /* * If we discover during ARC scan any buffers to be compressed, we boost * our headroom for the next scanning cycle by this percentage multiple. */ #define L2ARC_HEADROOM_BOOST 200 #define L2ARC_FEED_SECS 1 /* caching interval secs */ #define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */ #define l2arc_writes_sent ARCSTAT(arcstat_l2_writes_sent) #define l2arc_writes_done ARCSTAT(arcstat_l2_writes_done) /* L2ARC Performance Tunables */ uint64_t l2arc_write_max = L2ARC_WRITE_SIZE; /* default max write size */ uint64_t l2arc_write_boost = L2ARC_WRITE_SIZE; /* extra write during warmup */ uint64_t l2arc_headroom = L2ARC_HEADROOM; /* number of dev writes */ uint64_t l2arc_headroom_boost = L2ARC_HEADROOM_BOOST; uint64_t l2arc_feed_secs = L2ARC_FEED_SECS; /* interval seconds */ uint64_t l2arc_feed_min_ms = L2ARC_FEED_MIN_MS; /* min interval milliseconds */ boolean_t l2arc_noprefetch = B_TRUE; /* don't cache prefetch bufs */ boolean_t l2arc_feed_again = B_TRUE; /* turbo warmup */ boolean_t l2arc_norw = B_TRUE; /* no reads during writes */ SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, l2arc_write_max, CTLFLAG_RW, &l2arc_write_max, 0, "max write size"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, l2arc_write_boost, CTLFLAG_RW, &l2arc_write_boost, 0, "extra write during warmup"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, l2arc_headroom, CTLFLAG_RW, &l2arc_headroom, 0, "number of dev writes"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, l2arc_feed_secs, CTLFLAG_RW, &l2arc_feed_secs, 0, "interval seconds"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, l2arc_feed_min_ms, CTLFLAG_RW, &l2arc_feed_min_ms, 0, "min interval milliseconds"); SYSCTL_INT(_vfs_zfs, OID_AUTO, l2arc_noprefetch, CTLFLAG_RW, &l2arc_noprefetch, 0, "don't cache prefetch bufs"); SYSCTL_INT(_vfs_zfs, OID_AUTO, l2arc_feed_again, CTLFLAG_RW, &l2arc_feed_again, 0, "turbo warmup"); SYSCTL_INT(_vfs_zfs, OID_AUTO, l2arc_norw, CTLFLAG_RW, &l2arc_norw, 0, "no reads during writes"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, anon_size, CTLFLAG_RD, &ARC_anon.arcs_size, 0, "size of anonymous state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, anon_metadata_lsize, CTLFLAG_RD, &ARC_anon.arcs_lsize[ARC_BUFC_METADATA], 0, "size of anonymous state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, anon_data_lsize, CTLFLAG_RD, &ARC_anon.arcs_lsize[ARC_BUFC_DATA], 0, "size of anonymous state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mru_size, CTLFLAG_RD, &ARC_mru.arcs_size, 0, "size of mru state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mru_metadata_lsize, CTLFLAG_RD, &ARC_mru.arcs_lsize[ARC_BUFC_METADATA], 0, "size of metadata in mru state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mru_data_lsize, CTLFLAG_RD, &ARC_mru.arcs_lsize[ARC_BUFC_DATA], 0, "size of data in mru state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mru_ghost_size, CTLFLAG_RD, &ARC_mru_ghost.arcs_size, 0, "size of mru ghost state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mru_ghost_metadata_lsize, CTLFLAG_RD, &ARC_mru_ghost.arcs_lsize[ARC_BUFC_METADATA], 0, "size of metadata in mru ghost state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mru_ghost_data_lsize, CTLFLAG_RD, &ARC_mru_ghost.arcs_lsize[ARC_BUFC_DATA], 0, "size of data in mru ghost state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mfu_size, CTLFLAG_RD, &ARC_mfu.arcs_size, 0, "size of mfu state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mfu_metadata_lsize, CTLFLAG_RD, &ARC_mfu.arcs_lsize[ARC_BUFC_METADATA], 0, "size of metadata in mfu state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mfu_data_lsize, CTLFLAG_RD, &ARC_mfu.arcs_lsize[ARC_BUFC_DATA], 0, "size of data in mfu state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mfu_ghost_size, CTLFLAG_RD, &ARC_mfu_ghost.arcs_size, 0, "size of mfu ghost state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mfu_ghost_metadata_lsize, CTLFLAG_RD, &ARC_mfu_ghost.arcs_lsize[ARC_BUFC_METADATA], 0, "size of metadata in mfu ghost state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, mfu_ghost_data_lsize, CTLFLAG_RD, &ARC_mfu_ghost.arcs_lsize[ARC_BUFC_DATA], 0, "size of data in mfu ghost state"); SYSCTL_UQUAD(_vfs_zfs, OID_AUTO, l2c_only_size, CTLFLAG_RD, &ARC_l2c_only.arcs_size, 0, "size of mru state"); /* * L2ARC Internals */ typedef struct l2arc_dev { vdev_t *l2ad_vdev; /* vdev */ spa_t *l2ad_spa; /* spa */ uint64_t l2ad_hand; /* next write location */ uint64_t l2ad_start; /* first addr on device */ uint64_t l2ad_end; /* last addr on device */ uint64_t l2ad_evict; /* last addr eviction reached */ boolean_t l2ad_first; /* first sweep through */ boolean_t l2ad_writing; /* currently writing */ list_t *l2ad_buflist; /* buffer list */ list_node_t l2ad_node; /* device list node */ } l2arc_dev_t; static list_t L2ARC_dev_list; /* device list */ static list_t *l2arc_dev_list; /* device list pointer */ static kmutex_t l2arc_dev_mtx; /* device list mutex */ static l2arc_dev_t *l2arc_dev_last; /* last device used */ static kmutex_t l2arc_buflist_mtx; /* mutex for all buflists */ static list_t L2ARC_free_on_write; /* free after write buf list */ static list_t *l2arc_free_on_write; /* free after write list ptr */ static kmutex_t l2arc_free_on_write_mtx; /* mutex for list */ static uint64_t l2arc_ndev; /* number of devices */ typedef struct l2arc_read_callback { arc_buf_t *l2rcb_buf; /* read buffer */ spa_t *l2rcb_spa; /* spa */ blkptr_t l2rcb_bp; /* original blkptr */ zbookmark_phys_t l2rcb_zb; /* original bookmark */ int l2rcb_flags; /* original flags */ enum zio_compress l2rcb_compress; /* applied compress */ } l2arc_read_callback_t; typedef struct l2arc_write_callback { l2arc_dev_t *l2wcb_dev; /* device info */ arc_buf_hdr_t *l2wcb_head; /* head of write buflist */ } l2arc_write_callback_t; struct l2arc_buf_hdr { /* protected by arc_buf_hdr mutex */ l2arc_dev_t *b_dev; /* L2ARC device */ uint64_t b_daddr; /* disk address, offset byte */ /* compression applied to buffer data */ enum zio_compress b_compress; /* real alloc'd buffer size depending on b_compress applied */ int b_asize; /* temporary buffer holder for in-flight compressed data */ void *b_tmp_cdata; }; typedef struct l2arc_data_free { /* protected by l2arc_free_on_write_mtx */ void *l2df_data; size_t l2df_size; void (*l2df_func)(void *, size_t); list_node_t l2df_list_node; } l2arc_data_free_t; static kmutex_t l2arc_feed_thr_lock; static kcondvar_t l2arc_feed_thr_cv; static uint8_t l2arc_thread_exit; static void l2arc_read_done(zio_t *zio); static void l2arc_hdr_stat_add(void); static void l2arc_hdr_stat_remove(void); static boolean_t l2arc_compress_buf(l2arc_buf_hdr_t *l2hdr); static void l2arc_decompress_zio(zio_t *zio, arc_buf_hdr_t *hdr, enum zio_compress c); static void l2arc_release_cdata_buf(arc_buf_hdr_t *ab); static uint64_t buf_hash(uint64_t spa, const dva_t *dva, uint64_t birth) { uint8_t *vdva = (uint8_t *)dva; uint64_t crc = -1ULL; int i; ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY); for (i = 0; i < sizeof (dva_t); i++) crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ vdva[i]) & 0xFF]; crc ^= (spa>>8) ^ birth; return (crc); } #define BUF_EMPTY(buf) \ ((buf)->b_dva.dva_word[0] == 0 && \ (buf)->b_dva.dva_word[1] == 0 && \ (buf)->b_cksum0 == 0) #define BUF_EQUAL(spa, dva, birth, buf) \ ((buf)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \ ((buf)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \ ((buf)->b_birth == birth) && ((buf)->b_spa == spa) static void buf_discard_identity(arc_buf_hdr_t *hdr) { hdr->b_dva.dva_word[0] = 0; hdr->b_dva.dva_word[1] = 0; hdr->b_birth = 0; hdr->b_cksum0 = 0; } static arc_buf_hdr_t * buf_hash_find(uint64_t spa, const blkptr_t *bp, kmutex_t **lockp) { const dva_t *dva = BP_IDENTITY(bp); uint64_t birth = BP_PHYSICAL_BIRTH(bp); uint64_t idx = BUF_HASH_INDEX(spa, dva, birth); kmutex_t *hash_lock = BUF_HASH_LOCK(idx); arc_buf_hdr_t *buf; mutex_enter(hash_lock); for (buf = buf_hash_table.ht_table[idx]; buf != NULL; buf = buf->b_hash_next) { if (BUF_EQUAL(spa, dva, birth, buf)) { *lockp = hash_lock; return (buf); } } mutex_exit(hash_lock); *lockp = NULL; return (NULL); } /* * Insert an entry into the hash table. If there is already an element * equal to elem in the hash table, then the already existing element * will be returned and the new element will not be inserted. * Otherwise returns NULL. */ static arc_buf_hdr_t * buf_hash_insert(arc_buf_hdr_t *buf, kmutex_t **lockp) { uint64_t idx = BUF_HASH_INDEX(buf->b_spa, &buf->b_dva, buf->b_birth); kmutex_t *hash_lock = BUF_HASH_LOCK(idx); arc_buf_hdr_t *fbuf; uint32_t i; ASSERT(!DVA_IS_EMPTY(&buf->b_dva)); ASSERT(buf->b_birth != 0); ASSERT(!HDR_IN_HASH_TABLE(buf)); *lockp = hash_lock; mutex_enter(hash_lock); for (fbuf = buf_hash_table.ht_table[idx], i = 0; fbuf != NULL; fbuf = fbuf->b_hash_next, i++) { if (BUF_EQUAL(buf->b_spa, &buf->b_dva, buf->b_birth, fbuf)) return (fbuf); } buf->b_hash_next = buf_hash_table.ht_table[idx]; buf_hash_table.ht_table[idx] = buf; buf->b_flags |= ARC_IN_HASH_TABLE; /* collect some hash table performance data */ if (i > 0) { ARCSTAT_BUMP(arcstat_hash_collisions); if (i == 1) ARCSTAT_BUMP(arcstat_hash_chains); ARCSTAT_MAX(arcstat_hash_chain_max, i); } ARCSTAT_BUMP(arcstat_hash_elements); ARCSTAT_MAXSTAT(arcstat_hash_elements); return (NULL); } static void buf_hash_remove(arc_buf_hdr_t *buf) { arc_buf_hdr_t *fbuf, **bufp; uint64_t idx = BUF_HASH_INDEX(buf->b_spa, &buf->b_dva, buf->b_birth); ASSERT(MUTEX_HELD(BUF_HASH_LOCK(idx))); ASSERT(HDR_IN_HASH_TABLE(buf)); bufp = &buf_hash_table.ht_table[idx]; while ((fbuf = *bufp) != buf) { ASSERT(fbuf != NULL); bufp = &fbuf->b_hash_next; } *bufp = buf->b_hash_next; buf->b_hash_next = NULL; buf->b_flags &= ~ARC_IN_HASH_TABLE; /* collect some hash table performance data */ ARCSTAT_BUMPDOWN(arcstat_hash_elements); if (buf_hash_table.ht_table[idx] && buf_hash_table.ht_table[idx]->b_hash_next == NULL) ARCSTAT_BUMPDOWN(arcstat_hash_chains); } /* * Global data structures and functions for the buf kmem cache. */ static kmem_cache_t *hdr_cache; static kmem_cache_t *buf_cache; static void buf_fini(void) { int i; kmem_free(buf_hash_table.ht_table, (buf_hash_table.ht_mask + 1) * sizeof (void *)); for (i = 0; i < BUF_LOCKS; i++) mutex_destroy(&buf_hash_table.ht_locks[i].ht_lock); kmem_cache_destroy(hdr_cache); kmem_cache_destroy(buf_cache); } /* * Constructor callback - called when the cache is empty * and a new buf is requested. */ /* ARGSUSED */ static int hdr_cons(void *vbuf, void *unused, int kmflag) { arc_buf_hdr_t *buf = vbuf; bzero(buf, sizeof (arc_buf_hdr_t)); refcount_create(&buf->b_refcnt); cv_init(&buf->b_cv, NULL, CV_DEFAULT, NULL); mutex_init(&buf->b_freeze_lock, NULL, MUTEX_DEFAULT, NULL); arc_space_consume(sizeof (arc_buf_hdr_t), ARC_SPACE_HDRS); return (0); } /* ARGSUSED */ static int buf_cons(void *vbuf, void *unused, int kmflag) { arc_buf_t *buf = vbuf; bzero(buf, sizeof (arc_buf_t)); mutex_init(&buf->b_evict_lock, NULL, MUTEX_DEFAULT, NULL); arc_space_consume(sizeof (arc_buf_t), ARC_SPACE_HDRS); return (0); } /* * Destructor callback - called when a cached buf is * no longer required. */ /* ARGSUSED */ static void hdr_dest(void *vbuf, void *unused) { arc_buf_hdr_t *buf = vbuf; ASSERT(BUF_EMPTY(buf)); refcount_destroy(&buf->b_refcnt); cv_destroy(&buf->b_cv); mutex_destroy(&buf->b_freeze_lock); arc_space_return(sizeof (arc_buf_hdr_t), ARC_SPACE_HDRS); } /* ARGSUSED */ static void buf_dest(void *vbuf, void *unused) { arc_buf_t *buf = vbuf; mutex_destroy(&buf->b_evict_lock); arc_space_return(sizeof (arc_buf_t), ARC_SPACE_HDRS); } /* * Reclaim callback -- invoked when memory is low. */ /* ARGSUSED */ static void hdr_recl(void *unused) { dprintf("hdr_recl called\n"); /* * umem calls the reclaim func when we destroy the buf cache, * which is after we do arc_fini(). */ if (!arc_dead) cv_signal(&arc_reclaim_thr_cv); } static void buf_init(void) { uint64_t *ct; uint64_t hsize = 1ULL << 12; int i, j; /* * The hash table is big enough to fill all of physical memory * with an average block size of zfs_arc_average_blocksize (default 8K). * By default, the table will take up * totalmem * sizeof(void*) / 8K (1MB per GB with 8-byte pointers). */ while (hsize * zfs_arc_average_blocksize < (uint64_t)physmem * PAGESIZE) hsize <<= 1; retry: buf_hash_table.ht_mask = hsize - 1; buf_hash_table.ht_table = kmem_zalloc(hsize * sizeof (void*), KM_NOSLEEP); if (buf_hash_table.ht_table == NULL) { ASSERT(hsize > (1ULL << 8)); hsize >>= 1; goto retry; } hdr_cache = kmem_cache_create("arc_buf_hdr_t", sizeof (arc_buf_hdr_t), 0, hdr_cons, hdr_dest, hdr_recl, NULL, NULL, 0); buf_cache = kmem_cache_create("arc_buf_t", sizeof (arc_buf_t), 0, buf_cons, buf_dest, NULL, NULL, NULL, 0); for (i = 0; i < 256; i++) for (ct = zfs_crc64_table + i, *ct = i, j = 8; j > 0; j--) *ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY); for (i = 0; i < BUF_LOCKS; i++) { mutex_init(&buf_hash_table.ht_locks[i].ht_lock, NULL, MUTEX_DEFAULT, NULL); } } #define ARC_MINTIME (hz>>4) /* 62 ms */ static void arc_cksum_verify(arc_buf_t *buf) { zio_cksum_t zc; if (!(zfs_flags & ZFS_DEBUG_MODIFY)) return; mutex_enter(&buf->b_hdr->b_freeze_lock); if (buf->b_hdr->b_freeze_cksum == NULL || (buf->b_hdr->b_flags & ARC_IO_ERROR)) { mutex_exit(&buf->b_hdr->b_freeze_lock); return; } fletcher_2_native(buf->b_data, buf->b_hdr->b_size, &zc); if (!ZIO_CHECKSUM_EQUAL(*buf->b_hdr->b_freeze_cksum, zc)) panic("buffer modified while frozen!"); mutex_exit(&buf->b_hdr->b_freeze_lock); } static int arc_cksum_equal(arc_buf_t *buf) { zio_cksum_t zc; int equal; mutex_enter(&buf->b_hdr->b_freeze_lock); fletcher_2_native(buf->b_data, buf->b_hdr->b_size, &zc); equal = ZIO_CHECKSUM_EQUAL(*buf->b_hdr->b_freeze_cksum, zc); mutex_exit(&buf->b_hdr->b_freeze_lock); return (equal); } static void arc_cksum_compute(arc_buf_t *buf, boolean_t force) { if (!force && !(zfs_flags & ZFS_DEBUG_MODIFY)) return; mutex_enter(&buf->b_hdr->b_freeze_lock); if (buf->b_hdr->b_freeze_cksum != NULL) { mutex_exit(&buf->b_hdr->b_freeze_lock); return; } buf->b_hdr->b_freeze_cksum = kmem_alloc(sizeof (zio_cksum_t), KM_SLEEP); fletcher_2_native(buf->b_data, buf->b_hdr->b_size, buf->b_hdr->b_freeze_cksum); mutex_exit(&buf->b_hdr->b_freeze_lock); #ifdef illumos arc_buf_watch(buf); #endif /* illumos */ } #ifdef illumos #ifndef _KERNEL typedef struct procctl { long cmd; prwatch_t prwatch; } procctl_t; #endif /* ARGSUSED */ static void arc_buf_unwatch(arc_buf_t *buf) { #ifndef _KERNEL if (arc_watch) { int result; procctl_t ctl; ctl.cmd = PCWATCH; ctl.prwatch.pr_vaddr = (uintptr_t)buf->b_data; ctl.prwatch.pr_size = 0; ctl.prwatch.pr_wflags = 0; result = write(arc_procfd, &ctl, sizeof (ctl)); ASSERT3U(result, ==, sizeof (ctl)); } #endif } /* ARGSUSED */ static void arc_buf_watch(arc_buf_t *buf) { #ifndef _KERNEL if (arc_watch) { int result; procctl_t ctl; ctl.cmd = PCWATCH; ctl.prwatch.pr_vaddr = (uintptr_t)buf->b_data; ctl.prwatch.pr_size = buf->b_hdr->b_size; ctl.prwatch.pr_wflags = WA_WRITE; result = write(arc_procfd, &ctl, sizeof (ctl)); ASSERT3U(result, ==, sizeof (ctl)); } #endif } #endif /* illumos */ void arc_buf_thaw(arc_buf_t *buf) { if (zfs_flags & ZFS_DEBUG_MODIFY) { if (buf->b_hdr->b_state != arc_anon) panic("modifying non-anon buffer!"); if (buf->b_hdr->b_flags & ARC_IO_IN_PROGRESS) panic("modifying buffer while i/o in progress!"); arc_cksum_verify(buf); } mutex_enter(&buf->b_hdr->b_freeze_lock); if (buf->b_hdr->b_freeze_cksum != NULL) { kmem_free(buf->b_hdr->b_freeze_cksum, sizeof (zio_cksum_t)); buf->b_hdr->b_freeze_cksum = NULL; } if (zfs_flags & ZFS_DEBUG_MODIFY) { if (buf->b_hdr->b_thawed) kmem_free(buf->b_hdr->b_thawed, 1); buf->b_hdr->b_thawed = kmem_alloc(1, KM_SLEEP); } mutex_exit(&buf->b_hdr->b_freeze_lock); #ifdef illumos arc_buf_unwatch(buf); #endif /* illumos */ } void arc_buf_freeze(arc_buf_t *buf) { kmutex_t *hash_lock; if (!(zfs_flags & ZFS_DEBUG_MODIFY)) return; hash_lock = HDR_LOCK(buf->b_hdr); mutex_enter(hash_lock); ASSERT(buf->b_hdr->b_freeze_cksum != NULL || buf->b_hdr->b_state == arc_anon); arc_cksum_compute(buf, B_FALSE); mutex_exit(hash_lock); } static void get_buf_info(arc_buf_hdr_t *ab, arc_state_t *state, list_t **list, kmutex_t **lock) { uint64_t buf_hashid = buf_hash(ab->b_spa, &ab->b_dva, ab->b_birth); if (ab->b_type == ARC_BUFC_METADATA) buf_hashid &= (ARC_BUFC_NUMMETADATALISTS - 1); else { buf_hashid &= (ARC_BUFC_NUMDATALISTS - 1); buf_hashid += ARC_BUFC_NUMMETADATALISTS; } *list = &state->arcs_lists[buf_hashid]; *lock = ARCS_LOCK(state, buf_hashid); } static void add_reference(arc_buf_hdr_t *ab, kmutex_t *hash_lock, void *tag) { ASSERT(MUTEX_HELD(hash_lock)); if ((refcount_add(&ab->b_refcnt, tag) == 1) && (ab->b_state != arc_anon)) { uint64_t delta = ab->b_size * ab->b_datacnt; uint64_t *size = &ab->b_state->arcs_lsize[ab->b_type]; list_t *list; kmutex_t *lock; get_buf_info(ab, ab->b_state, &list, &lock); ASSERT(!MUTEX_HELD(lock)); mutex_enter(lock); ASSERT(list_link_active(&ab->b_arc_node)); list_remove(list, ab); if (GHOST_STATE(ab->b_state)) { ASSERT0(ab->b_datacnt); ASSERT3P(ab->b_buf, ==, NULL); delta = ab->b_size; } ASSERT(delta > 0); ASSERT3U(*size, >=, delta); atomic_add_64(size, -delta); mutex_exit(lock); /* remove the prefetch flag if we get a reference */ if (ab->b_flags & ARC_PREFETCH) ab->b_flags &= ~ARC_PREFETCH; } } static int remove_reference(arc_buf_hdr_t *ab, kmutex_t *hash_lock, void *tag) { int cnt; arc_state_t *state = ab->b_state; ASSERT(state == arc_anon || MUTEX_HELD(hash_lock)); ASSERT(!GHOST_STATE(state)); if (((cnt = refcount_remove(&ab->b_refcnt, tag)) == 0) && (state != arc_anon)) { uint64_t *size = &state->arcs_lsize[ab->b_type]; list_t *list; kmutex_t *lock; get_buf_info(ab, state, &list, &lock); ASSERT(!MUTEX_HELD(lock)); mutex_enter(lock); ASSERT(!list_link_active(&ab->b_arc_node)); list_insert_head(list, ab); ASSERT(ab->b_datacnt > 0); atomic_add_64(size, ab->b_size * ab->b_datacnt); mutex_exit(lock); } return (cnt); } /* * Move the supplied buffer to the indicated state. The mutex * for the buffer must be held by the caller. */ static void arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *ab, kmutex_t *hash_lock) { arc_state_t *old_state = ab->b_state; int64_t refcnt = refcount_count(&ab->b_refcnt); uint64_t from_delta, to_delta; list_t *list; kmutex_t *lock; ASSERT(MUTEX_HELD(hash_lock)); ASSERT3P(new_state, !=, old_state); ASSERT(refcnt == 0 || ab->b_datacnt > 0); ASSERT(ab->b_datacnt == 0 || !GHOST_STATE(new_state)); ASSERT(ab->b_datacnt <= 1 || old_state != arc_anon); from_delta = to_delta = ab->b_datacnt * ab->b_size; /* * If this buffer is evictable, transfer it from the * old state list to the new state list. */ if (refcnt == 0) { if (old_state != arc_anon) { int use_mutex; uint64_t *size = &old_state->arcs_lsize[ab->b_type]; get_buf_info(ab, old_state, &list, &lock); use_mutex = !MUTEX_HELD(lock); if (use_mutex) mutex_enter(lock); ASSERT(list_link_active(&ab->b_arc_node)); list_remove(list, ab); /* * If prefetching out of the ghost cache, * we will have a non-zero datacnt. */ if (GHOST_STATE(old_state) && ab->b_datacnt == 0) { /* ghost elements have a ghost size */ ASSERT(ab->b_buf == NULL); from_delta = ab->b_size; } ASSERT3U(*size, >=, from_delta); atomic_add_64(size, -from_delta); if (use_mutex) mutex_exit(lock); } if (new_state != arc_anon) { int use_mutex; uint64_t *size = &new_state->arcs_lsize[ab->b_type]; get_buf_info(ab, new_state, &list, &lock); use_mutex = !MUTEX_HELD(lock); if (use_mutex) mutex_enter(lock); list_insert_head(list, ab); /* ghost elements have a ghost size */ if (GHOST_STATE(new_state)) { ASSERT(ab->b_datacnt == 0); ASSERT(ab->b_buf == NULL); to_delta = ab->b_size; } atomic_add_64(size, to_delta); if (use_mutex) mutex_exit(lock); } } ASSERT(!BUF_EMPTY(ab)); if (new_state == arc_anon && HDR_IN_HASH_TABLE(ab)) buf_hash_remove(ab); /* adjust state sizes */ if (to_delta) atomic_add_64(&new_state->arcs_size, to_delta); if (from_delta) { ASSERT3U(old_state->arcs_size, >=, from_delta); atomic_add_64(&old_state->arcs_size, -from_delta); } ab->b_state = new_state; /* adjust l2arc hdr stats */ if (new_state == arc_l2c_only) l2arc_hdr_stat_add(); else if (old_state == arc_l2c_only) l2arc_hdr_stat_remove(); } void arc_space_consume(uint64_t space, arc_space_type_t type) { ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES); switch (type) { case ARC_SPACE_DATA: ARCSTAT_INCR(arcstat_data_size, space); break; case ARC_SPACE_OTHER: ARCSTAT_INCR(arcstat_other_size, space); break; case ARC_SPACE_HDRS: ARCSTAT_INCR(arcstat_hdr_size, space); break; case ARC_SPACE_L2HDRS: ARCSTAT_INCR(arcstat_l2_hdr_size, space); break; } atomic_add_64(&arc_meta_used, space); atomic_add_64(&arc_size, space); } void arc_space_return(uint64_t space, arc_space_type_t type) { ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES); switch (type) { case ARC_SPACE_DATA: ARCSTAT_INCR(arcstat_data_size, -space); break; case ARC_SPACE_OTHER: ARCSTAT_INCR(arcstat_other_size, -space); break; case ARC_SPACE_HDRS: ARCSTAT_INCR(arcstat_hdr_size, -space); break; case ARC_SPACE_L2HDRS: ARCSTAT_INCR(arcstat_l2_hdr_size, -space); break; } ASSERT(arc_meta_used >= space); if (arc_meta_max < arc_meta_used) arc_meta_max = arc_meta_used; atomic_add_64(&arc_meta_used, -space); ASSERT(arc_size >= space); atomic_add_64(&arc_size, -space); } void * arc_data_buf_alloc(uint64_t size) { if (arc_evict_needed(ARC_BUFC_DATA)) cv_signal(&arc_reclaim_thr_cv); atomic_add_64(&arc_size, size); return (zio_data_buf_alloc(size)); } void arc_data_buf_free(void *buf, uint64_t size) { zio_data_buf_free(buf, size); ASSERT(arc_size >= size); atomic_add_64(&arc_size, -size); } arc_buf_t * arc_buf_alloc(spa_t *spa, int size, void *tag, arc_buf_contents_t type) { arc_buf_hdr_t *hdr; arc_buf_t *buf; ASSERT3U(size, >, 0); hdr = kmem_cache_alloc(hdr_cache, KM_PUSHPAGE); ASSERT(BUF_EMPTY(hdr)); hdr->b_size = size; hdr->b_type = type; hdr->b_spa = spa_load_guid(spa); hdr->b_state = arc_anon; hdr->b_arc_access = 0; buf = kmem_cache_alloc(buf_cache, KM_PUSHPAGE); buf->b_hdr = hdr; buf->b_data = NULL; buf->b_efunc = NULL; buf->b_private = NULL; buf->b_next = NULL; hdr->b_buf = buf; arc_get_data_buf(buf); hdr->b_datacnt = 1; hdr->b_flags = 0; ASSERT(refcount_is_zero(&hdr->b_refcnt)); (void) refcount_add(&hdr->b_refcnt, tag); return (buf); } static char *arc_onloan_tag = "onloan"; /* * Loan out an anonymous arc buffer. Loaned buffers are not counted as in * flight data by arc_tempreserve_space() until they are "returned". Loaned * buffers must be returned to the arc before they can be used by the DMU or * freed. */ arc_buf_t * arc_loan_buf(spa_t *spa, int size) { arc_buf_t *buf; buf = arc_buf_alloc(spa, size, arc_onloan_tag, ARC_BUFC_DATA); atomic_add_64(&arc_loaned_bytes, size); return (buf); } /* * Return a loaned arc buffer to the arc. */ void arc_return_buf(arc_buf_t *buf, void *tag) { arc_buf_hdr_t *hdr = buf->b_hdr; ASSERT(buf->b_data != NULL); (void) refcount_add(&hdr->b_refcnt, tag); (void) refcount_remove(&hdr->b_refcnt, arc_onloan_tag); atomic_add_64(&arc_loaned_bytes, -hdr->b_size); } /* Detach an arc_buf from a dbuf (tag) */ void arc_loan_inuse_buf(arc_buf_t *buf, void *tag) { arc_buf_hdr_t *hdr; ASSERT(buf->b_data != NULL); hdr = buf->b_hdr; (void) refcount_add(&hdr->b_refcnt, arc_onloan_tag); (void) refcount_remove(&hdr->b_refcnt, tag); buf->b_efunc = NULL; buf->b_private = NULL; atomic_add_64(&arc_loaned_bytes, hdr->b_size); } static arc_buf_t * arc_buf_clone(arc_buf_t *from) { arc_buf_t *buf; arc_buf_hdr_t *hdr = from->b_hdr; uint64_t size = hdr->b_size; ASSERT(hdr->b_state != arc_anon); buf = kmem_cache_alloc(buf_cache, KM_PUSHPAGE); buf->b_hdr = hdr; buf->b_data = NULL; buf->b_efunc = NULL; buf->b_private = NULL; buf->b_next = hdr->b_buf; hdr->b_buf = buf; arc_get_data_buf(buf); bcopy(from->b_data, buf->b_data, size); /* * This buffer already exists in the arc so create a duplicate * copy for the caller. If the buffer is associated with user data * then track the size and number of duplicates. These stats will be * updated as duplicate buffers are created and destroyed. */ if (hdr->b_type == ARC_BUFC_DATA) { ARCSTAT_BUMP(arcstat_duplicate_buffers); ARCSTAT_INCR(arcstat_duplicate_buffers_size, size); } hdr->b_datacnt += 1; return (buf); } void arc_buf_add_ref(arc_buf_t *buf, void* tag) { arc_buf_hdr_t *hdr; kmutex_t *hash_lock; /* * Check to see if this buffer is evicted. Callers * must verify b_data != NULL to know if the add_ref * was successful. */ mutex_enter(&buf->b_evict_lock); if (buf->b_data == NULL) { mutex_exit(&buf->b_evict_lock); return; } hash_lock = HDR_LOCK(buf->b_hdr); mutex_enter(hash_lock); hdr = buf->b_hdr; ASSERT3P(hash_lock, ==, HDR_LOCK(hdr)); mutex_exit(&buf->b_evict_lock); ASSERT(hdr->b_state == arc_mru || hdr->b_state == arc_mfu); add_reference(hdr, hash_lock, tag); DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr); arc_access(hdr, hash_lock); mutex_exit(hash_lock); ARCSTAT_BUMP(arcstat_hits); ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH), demand, prefetch, hdr->b_type != ARC_BUFC_METADATA, data, metadata, hits); } /* * Free the arc data buffer. If it is an l2arc write in progress, * the buffer is placed on l2arc_free_on_write to be freed later. */ static void arc_buf_data_free(arc_buf_t *buf, void (*free_func)(void *, size_t)) { arc_buf_hdr_t *hdr = buf->b_hdr; if (HDR_L2_WRITING(hdr)) { l2arc_data_free_t *df; df = kmem_alloc(sizeof (l2arc_data_free_t), KM_SLEEP); df->l2df_data = buf->b_data; df->l2df_size = hdr->b_size; df->l2df_func = free_func; mutex_enter(&l2arc_free_on_write_mtx); list_insert_head(l2arc_free_on_write, df); mutex_exit(&l2arc_free_on_write_mtx); ARCSTAT_BUMP(arcstat_l2_free_on_write); } else { free_func(buf->b_data, hdr->b_size); } } /* * Free up buf->b_data and if 'remove' is set, then pull the * arc_buf_t off of the the arc_buf_hdr_t's list and free it. */ static void arc_buf_destroy(arc_buf_t *buf, boolean_t recycle, boolean_t remove) { arc_buf_t **bufp; /* free up data associated with the buf */ if (buf->b_data) { arc_state_t *state = buf->b_hdr->b_state; uint64_t size = buf->b_hdr->b_size; arc_buf_contents_t type = buf->b_hdr->b_type; arc_cksum_verify(buf); #ifdef illumos arc_buf_unwatch(buf); #endif /* illumos */ if (!recycle) { if (type == ARC_BUFC_METADATA) { arc_buf_data_free(buf, zio_buf_free); arc_space_return(size, ARC_SPACE_DATA); } else { ASSERT(type == ARC_BUFC_DATA); arc_buf_data_free(buf, zio_data_buf_free); ARCSTAT_INCR(arcstat_data_size, -size); atomic_add_64(&arc_size, -size); } } if (list_link_active(&buf->b_hdr->b_arc_node)) { uint64_t *cnt = &state->arcs_lsize[type]; ASSERT(refcount_is_zero(&buf->b_hdr->b_refcnt)); ASSERT(state != arc_anon); ASSERT3U(*cnt, >=, size); atomic_add_64(cnt, -size); } ASSERT3U(state->arcs_size, >=, size); atomic_add_64(&state->arcs_size, -size); buf->b_data = NULL; /* * If we're destroying a duplicate buffer make sure * that the appropriate statistics are updated. */ if (buf->b_hdr->b_datacnt > 1 && buf->b_hdr->b_type == ARC_BUFC_DATA) { ARCSTAT_BUMPDOWN(arcstat_duplicate_buffers); ARCSTAT_INCR(arcstat_duplicate_buffers_size, -size); } ASSERT(buf->b_hdr->b_datacnt > 0); buf->b_hdr->b_datacnt -= 1; } /* only remove the buf if requested */ if (!remove) return; /* remove the buf from the hdr list */ for (bufp = &buf->b_hdr->b_buf; *bufp != buf; bufp = &(*bufp)->b_next) continue; *bufp = buf->b_next; buf->b_next = NULL; ASSERT(buf->b_efunc == NULL); /* clean up the buf */ buf->b_hdr = NULL; kmem_cache_free(buf_cache, buf); } static void arc_hdr_destroy(arc_buf_hdr_t *hdr) { ASSERT(refcount_is_zero(&hdr->b_refcnt)); ASSERT3P(hdr->b_state, ==, arc_anon); ASSERT(!HDR_IO_IN_PROGRESS(hdr)); l2arc_buf_hdr_t *l2hdr = hdr->b_l2hdr; if (l2hdr != NULL) { boolean_t buflist_held = MUTEX_HELD(&l2arc_buflist_mtx); /* * To prevent arc_free() and l2arc_evict() from * attempting to free the same buffer at the same time, * a FREE_IN_PROGRESS flag is given to arc_free() to * give it priority. l2arc_evict() can't destroy this * header while we are waiting on l2arc_buflist_mtx. * * The hdr may be removed from l2ad_buflist before we * grab l2arc_buflist_mtx, so b_l2hdr is rechecked. */ if (!buflist_held) { mutex_enter(&l2arc_buflist_mtx); l2hdr = hdr->b_l2hdr; } if (l2hdr != NULL) { trim_map_free(l2hdr->b_dev->l2ad_vdev, l2hdr->b_daddr, hdr->b_size, 0); list_remove(l2hdr->b_dev->l2ad_buflist, hdr); ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size); ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize); vdev_space_update(l2hdr->b_dev->l2ad_vdev, -l2hdr->b_asize, 0, 0); kmem_free(l2hdr, sizeof (l2arc_buf_hdr_t)); if (hdr->b_state == arc_l2c_only) l2arc_hdr_stat_remove(); hdr->b_l2hdr = NULL; } if (!buflist_held) mutex_exit(&l2arc_buflist_mtx); } if (!BUF_EMPTY(hdr)) { ASSERT(!HDR_IN_HASH_TABLE(hdr)); buf_discard_identity(hdr); } while (hdr->b_buf) { arc_buf_t *buf = hdr->b_buf; if (buf->b_efunc) { mutex_enter(&arc_eviction_mtx); mutex_enter(&buf->b_evict_lock); ASSERT(buf->b_hdr != NULL); arc_buf_destroy(hdr->b_buf, FALSE, FALSE); hdr->b_buf = buf->b_next; buf->b_hdr = &arc_eviction_hdr; buf->b_next = arc_eviction_list; arc_eviction_list = buf; mutex_exit(&buf->b_evict_lock); mutex_exit(&arc_eviction_mtx); } else { arc_buf_destroy(hdr->b_buf, FALSE, TRUE); } } if (hdr->b_freeze_cksum != NULL) { kmem_free(hdr->b_freeze_cksum, sizeof (zio_cksum_t)); hdr->b_freeze_cksum = NULL; } if (hdr->b_thawed) { kmem_free(hdr->b_thawed, 1); hdr->b_thawed = NULL; } ASSERT(!list_link_active(&hdr->b_arc_node)); ASSERT3P(hdr->b_hash_next, ==, NULL); ASSERT3P(hdr->b_acb, ==, NULL); kmem_cache_free(hdr_cache, hdr); } void arc_buf_free(arc_buf_t *buf, void *tag) { arc_buf_hdr_t *hdr = buf->b_hdr; int hashed = hdr->b_state != arc_anon; ASSERT(buf->b_efunc == NULL); ASSERT(buf->b_data != NULL); if (hashed) { kmutex_t *hash_lock = HDR_LOCK(hdr); mutex_enter(hash_lock); hdr = buf->b_hdr; ASSERT3P(hash_lock, ==, HDR_LOCK(hdr)); (void) remove_reference(hdr, hash_lock, tag); if (hdr->b_datacnt > 1) { arc_buf_destroy(buf, FALSE, TRUE); } else { ASSERT(buf == hdr->b_buf); ASSERT(buf->b_efunc == NULL); hdr->b_flags |= ARC_BUF_AVAILABLE; } mutex_exit(hash_lock); } else if (HDR_IO_IN_PROGRESS(hdr)) { int destroy_hdr; /* * We are in the middle of an async write. Don't destroy * this buffer unless the write completes before we finish * decrementing the reference count. */ mutex_enter(&arc_eviction_mtx); (void) remove_reference(hdr, NULL, tag); ASSERT(refcount_is_zero(&hdr->b_refcnt)); destroy_hdr = !HDR_IO_IN_PROGRESS(hdr); mutex_exit(&arc_eviction_mtx); if (destroy_hdr) arc_hdr_destroy(hdr); } else { if (remove_reference(hdr, NULL, tag) > 0) arc_buf_destroy(buf, FALSE, TRUE); else arc_hdr_destroy(hdr); } } boolean_t arc_buf_remove_ref(arc_buf_t *buf, void* tag) { arc_buf_hdr_t *hdr = buf->b_hdr; kmutex_t *hash_lock = HDR_LOCK(hdr); boolean_t no_callback = (buf->b_efunc == NULL); if (hdr->b_state == arc_anon) { ASSERT(hdr->b_datacnt == 1); arc_buf_free(buf, tag); return (no_callback); } mutex_enter(hash_lock); hdr = buf->b_hdr; ASSERT3P(hash_lock, ==, HDR_LOCK(hdr)); ASSERT(hdr->b_state != arc_anon); ASSERT(buf->b_data != NULL); (void) remove_reference(hdr, hash_lock, tag); if (hdr->b_datacnt > 1) { if (no_callback) arc_buf_destroy(buf, FALSE, TRUE); } else if (no_callback) { ASSERT(hdr->b_buf == buf && buf->b_next == NULL); ASSERT(buf->b_efunc == NULL); hdr->b_flags |= ARC_BUF_AVAILABLE; } ASSERT(no_callback || hdr->b_datacnt > 1 || refcount_is_zero(&hdr->b_refcnt)); mutex_exit(hash_lock); return (no_callback); } int arc_buf_size(arc_buf_t *buf) { return (buf->b_hdr->b_size); } /* * Called from the DMU to determine if the current buffer should be * evicted. In order to ensure proper locking, the eviction must be initiated * from the DMU. Return true if the buffer is associated with user data and * duplicate buffers still exist. */ boolean_t arc_buf_eviction_needed(arc_buf_t *buf) { arc_buf_hdr_t *hdr; boolean_t evict_needed = B_FALSE; if (zfs_disable_dup_eviction) return (B_FALSE); mutex_enter(&buf->b_evict_lock); hdr = buf->b_hdr; if (hdr == NULL) { /* * We are in arc_do_user_evicts(); let that function * perform the eviction. */ ASSERT(buf->b_data == NULL); mutex_exit(&buf->b_evict_lock); return (B_FALSE); } else if (buf->b_data == NULL) { /* * We have already been added to the arc eviction list; * recommend eviction. */ ASSERT3P(hdr, ==, &arc_eviction_hdr); mutex_exit(&buf->b_evict_lock); return (B_TRUE); } if (hdr->b_datacnt > 1 && hdr->b_type == ARC_BUFC_DATA) evict_needed = B_TRUE; mutex_exit(&buf->b_evict_lock); return (evict_needed); } /* * Evict buffers from list until we've removed the specified number of * bytes. Move the removed buffers to the appropriate evict state. * If the recycle flag is set, then attempt to "recycle" a buffer: * - look for a buffer to evict that is `bytes' long. * - return the data block from this buffer rather than freeing it. * This flag is used by callers that are trying to make space for a * new buffer in a full arc cache. * * This function makes a "best effort". It skips over any buffers * it can't get a hash_lock on, and so may not catch all candidates. * It may also return without evicting as much space as requested. */ static void * arc_evict(arc_state_t *state, uint64_t spa, int64_t bytes, boolean_t recycle, arc_buf_contents_t type) { arc_state_t *evicted_state; uint64_t bytes_evicted = 0, skipped = 0, missed = 0; int64_t bytes_remaining; arc_buf_hdr_t *ab, *ab_prev = NULL; list_t *evicted_list, *list, *evicted_list_start, *list_start; kmutex_t *lock, *evicted_lock; kmutex_t *hash_lock; boolean_t have_lock; void *stolen = NULL; arc_buf_hdr_t marker = { 0 }; int count = 0; static int evict_metadata_offset, evict_data_offset; int i, idx, offset, list_count, lists; ASSERT(state == arc_mru || state == arc_mfu); evicted_state = (state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost; if (type == ARC_BUFC_METADATA) { offset = 0; list_count = ARC_BUFC_NUMMETADATALISTS; list_start = &state->arcs_lists[0]; evicted_list_start = &evicted_state->arcs_lists[0]; idx = evict_metadata_offset; } else { offset = ARC_BUFC_NUMMETADATALISTS; list_start = &state->arcs_lists[offset]; evicted_list_start = &evicted_state->arcs_lists[offset]; list_count = ARC_BUFC_NUMDATALISTS; idx = evict_data_offset; } bytes_remaining = evicted_state->arcs_lsize[type]; lists = 0; evict_start: list = &list_start[idx]; evicted_list = &evicted_list_start[idx]; lock = ARCS_LOCK(state, (offset + idx)); evicted_lock = ARCS_LOCK(evicted_state, (offset + idx)); mutex_enter(lock); mutex_enter(evicted_lock); for (ab = list_tail(list); ab; ab = ab_prev) { ab_prev = list_prev(list, ab); bytes_remaining -= (ab->b_size * ab->b_datacnt); /* prefetch buffers have a minimum lifespan */ if (HDR_IO_IN_PROGRESS(ab) || (spa && ab->b_spa != spa) || (ab->b_flags & (ARC_PREFETCH|ARC_INDIRECT) && ddi_get_lbolt() - ab->b_arc_access < arc_min_prefetch_lifespan)) { skipped++; continue; } /* "lookahead" for better eviction candidate */ if (recycle && ab->b_size != bytes && ab_prev && ab_prev->b_size == bytes) continue; /* ignore markers */ if (ab->b_spa == 0) continue; /* * It may take a long time to evict all the bufs requested. * To avoid blocking all arc activity, periodically drop * the arcs_mtx and give other threads a chance to run * before reacquiring the lock. * * If we are looking for a buffer to recycle, we are in * the hot code path, so don't sleep. */ if (!recycle && count++ > arc_evict_iterations) { list_insert_after(list, ab, &marker); mutex_exit(evicted_lock); mutex_exit(lock); kpreempt(KPREEMPT_SYNC); mutex_enter(lock); mutex_enter(evicted_lock); ab_prev = list_prev(list, &marker); list_remove(list, &marker); count = 0; continue; } hash_lock = HDR_LOCK(ab); have_lock = MUTEX_HELD(hash_lock); if (have_lock || mutex_tryenter(hash_lock)) { ASSERT0(refcount_count(&ab->b_refcnt)); ASSERT(ab->b_datacnt > 0); while (ab->b_buf) { arc_buf_t *buf = ab->b_buf; if (!mutex_tryenter(&buf->b_evict_lock)) { missed += 1; break; } if (buf->b_data) { bytes_evicted += ab->b_size; if (recycle && ab->b_type == type && ab->b_size == bytes && !HDR_L2_WRITING(ab)) { stolen = buf->b_data; recycle = FALSE; } } if (buf->b_efunc) { mutex_enter(&arc_eviction_mtx); arc_buf_destroy(buf, buf->b_data == stolen, FALSE); ab->b_buf = buf->b_next; buf->b_hdr = &arc_eviction_hdr; buf->b_next = arc_eviction_list; arc_eviction_list = buf; mutex_exit(&arc_eviction_mtx); mutex_exit(&buf->b_evict_lock); } else { mutex_exit(&buf->b_evict_lock); arc_buf_destroy(buf, buf->b_data == stolen, TRUE); } } if (ab->b_l2hdr) { ARCSTAT_INCR(arcstat_evict_l2_cached, ab->b_size); } else { if (l2arc_write_eligible(ab->b_spa, ab)) { ARCSTAT_INCR(arcstat_evict_l2_eligible, ab->b_size); } else { ARCSTAT_INCR( arcstat_evict_l2_ineligible, ab->b_size); } } if (ab->b_datacnt == 0) { arc_change_state(evicted_state, ab, hash_lock); ASSERT(HDR_IN_HASH_TABLE(ab)); ab->b_flags |= ARC_IN_HASH_TABLE; ab->b_flags &= ~ARC_BUF_AVAILABLE; DTRACE_PROBE1(arc__evict, arc_buf_hdr_t *, ab); } if (!have_lock) mutex_exit(hash_lock); if (bytes >= 0 && bytes_evicted >= bytes) break; if (bytes_remaining > 0) { mutex_exit(evicted_lock); mutex_exit(lock); idx = ((idx + 1) & (list_count - 1)); lists++; goto evict_start; } } else { missed += 1; } } mutex_exit(evicted_lock); mutex_exit(lock); idx = ((idx + 1) & (list_count - 1)); lists++; if (bytes_evicted < bytes) { if (lists < list_count) goto evict_start; else dprintf("only evicted %lld bytes from %x", (longlong_t)bytes_evicted, state); } if (type == ARC_BUFC_METADATA) evict_metadata_offset = idx; else evict_data_offset = idx; if (skipped) ARCSTAT_INCR(arcstat_evict_skip, skipped); if (missed) ARCSTAT_INCR(arcstat_mutex_miss, missed); /* * Note: we have just evicted some data into the ghost state, * potentially putting the ghost size over the desired size. Rather * that evicting from the ghost list in this hot code path, leave * this chore to the arc_reclaim_thread(). */ if (stolen) ARCSTAT_BUMP(arcstat_stolen); return (stolen); } /* * Remove buffers from list until we've removed the specified number of * bytes. Destroy the buffers that are removed. */ static void arc_evict_ghost(arc_state_t *state, uint64_t spa, int64_t bytes) { arc_buf_hdr_t *ab, *ab_prev; arc_buf_hdr_t marker = { 0 }; list_t *list, *list_start; kmutex_t *hash_lock, *lock; uint64_t bytes_deleted = 0; uint64_t bufs_skipped = 0; int count = 0; static int evict_offset; int list_count, idx = evict_offset; int offset, lists = 0; ASSERT(GHOST_STATE(state)); /* * data lists come after metadata lists */ list_start = &state->arcs_lists[ARC_BUFC_NUMMETADATALISTS]; list_count = ARC_BUFC_NUMDATALISTS; offset = ARC_BUFC_NUMMETADATALISTS; evict_start: list = &list_start[idx]; lock = ARCS_LOCK(state, idx + offset); mutex_enter(lock); for (ab = list_tail(list); ab; ab = ab_prev) { ab_prev = list_prev(list, ab); if (ab->b_type > ARC_BUFC_NUMTYPES) panic("invalid ab=%p", (void *)ab); if (spa && ab->b_spa != spa) continue; /* ignore markers */ if (ab->b_spa == 0) continue; hash_lock = HDR_LOCK(ab); /* caller may be trying to modify this buffer, skip it */ if (MUTEX_HELD(hash_lock)) continue; /* * It may take a long time to evict all the bufs requested. * To avoid blocking all arc activity, periodically drop * the arcs_mtx and give other threads a chance to run * before reacquiring the lock. */ if (count++ > arc_evict_iterations) { list_insert_after(list, ab, &marker); mutex_exit(lock); kpreempt(KPREEMPT_SYNC); mutex_enter(lock); ab_prev = list_prev(list, &marker); list_remove(list, &marker); count = 0; continue; } if (mutex_tryenter(hash_lock)) { ASSERT(!HDR_IO_IN_PROGRESS(ab)); ASSERT(ab->b_buf == NULL); ARCSTAT_BUMP(arcstat_deleted); bytes_deleted += ab->b_size; if (ab->b_l2hdr != NULL) { /* * This buffer is cached on the 2nd Level ARC; * don't destroy the header. */ arc_change_state(arc_l2c_only, ab, hash_lock); mutex_exit(hash_lock); } else { arc_change_state(arc_anon, ab, hash_lock); mutex_exit(hash_lock); arc_hdr_destroy(ab); } DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, ab); if (bytes >= 0 && bytes_deleted >= bytes) break; } else if (bytes < 0) { /* * Insert a list marker and then wait for the * hash lock to become available. Once its * available, restart from where we left off. */ list_insert_after(list, ab, &marker); mutex_exit(lock); mutex_enter(hash_lock); mutex_exit(hash_lock); mutex_enter(lock); ab_prev = list_prev(list, &marker); list_remove(list, &marker); } else { bufs_skipped += 1; } } mutex_exit(lock); idx = ((idx + 1) & (ARC_BUFC_NUMDATALISTS - 1)); lists++; if (lists < list_count) goto evict_start; evict_offset = idx; if ((uintptr_t)list > (uintptr_t)&state->arcs_lists[ARC_BUFC_NUMMETADATALISTS] && (bytes < 0 || bytes_deleted < bytes)) { list_start = &state->arcs_lists[0]; list_count = ARC_BUFC_NUMMETADATALISTS; offset = lists = 0; goto evict_start; } if (bufs_skipped) { ARCSTAT_INCR(arcstat_mutex_miss, bufs_skipped); ASSERT(bytes >= 0); } if (bytes_deleted < bytes) dprintf("only deleted %lld bytes from %p", (longlong_t)bytes_deleted, state); } static void arc_adjust(void) { int64_t adjustment, delta; /* * Adjust MRU size */ adjustment = MIN((int64_t)(arc_size - arc_c), (int64_t)(arc_anon->arcs_size + arc_mru->arcs_size + arc_meta_used - arc_p)); if (adjustment > 0 && arc_mru->arcs_lsize[ARC_BUFC_DATA] > 0) { delta = MIN(arc_mru->arcs_lsize[ARC_BUFC_DATA], adjustment); (void) arc_evict(arc_mru, 0, delta, FALSE, ARC_BUFC_DATA); adjustment -= delta; } if (adjustment > 0 && arc_mru->arcs_lsize[ARC_BUFC_METADATA] > 0) { delta = MIN(arc_mru->arcs_lsize[ARC_BUFC_METADATA], adjustment); (void) arc_evict(arc_mru, 0, delta, FALSE, ARC_BUFC_METADATA); } /* * Adjust MFU size */ adjustment = arc_size - arc_c; if (adjustment > 0 && arc_mfu->arcs_lsize[ARC_BUFC_DATA] > 0) { delta = MIN(adjustment, arc_mfu->arcs_lsize[ARC_BUFC_DATA]); (void) arc_evict(arc_mfu, 0, delta, FALSE, ARC_BUFC_DATA); adjustment -= delta; } if (adjustment > 0 && arc_mfu->arcs_lsize[ARC_BUFC_METADATA] > 0) { int64_t delta = MIN(adjustment, arc_mfu->arcs_lsize[ARC_BUFC_METADATA]); (void) arc_evict(arc_mfu, 0, delta, FALSE, ARC_BUFC_METADATA); } /* * Adjust ghost lists */ adjustment = arc_mru->arcs_size + arc_mru_ghost->arcs_size - arc_c; if (adjustment > 0 && arc_mru_ghost->arcs_size > 0) { delta = MIN(arc_mru_ghost->arcs_size, adjustment); arc_evict_ghost(arc_mru_ghost, 0, delta); } adjustment = arc_mru_ghost->arcs_size + arc_mfu_ghost->arcs_size - arc_c; if (adjustment > 0 && arc_mfu_ghost->arcs_size > 0) { delta = MIN(arc_mfu_ghost->arcs_size, adjustment); arc_evict_ghost(arc_mfu_ghost, 0, delta); } } static void arc_do_user_evicts(void) { static arc_buf_t *tmp_arc_eviction_list; /* * Move list over to avoid LOR */ restart: mutex_enter(&arc_eviction_mtx); tmp_arc_eviction_list = arc_eviction_list; arc_eviction_list = NULL; mutex_exit(&arc_eviction_mtx); while (tmp_arc_eviction_list != NULL) { arc_buf_t *buf = tmp_arc_eviction_list; tmp_arc_eviction_list = buf->b_next; mutex_enter(&buf->b_evict_lock); buf->b_hdr = NULL; mutex_exit(&buf->b_evict_lock); if (buf->b_efunc != NULL) VERIFY0(buf->b_efunc(buf->b_private)); buf->b_efunc = NULL; buf->b_private = NULL; kmem_cache_free(buf_cache, buf); } if (arc_eviction_list != NULL) goto restart; } /* * Flush all *evictable* data from the cache for the given spa. * NOTE: this will not touch "active" (i.e. referenced) data. */ void arc_flush(spa_t *spa) { uint64_t guid = 0; if (spa) guid = spa_load_guid(spa); while (arc_mru->arcs_lsize[ARC_BUFC_DATA]) { (void) arc_evict(arc_mru, guid, -1, FALSE, ARC_BUFC_DATA); if (spa) break; } while (arc_mru->arcs_lsize[ARC_BUFC_METADATA]) { (void) arc_evict(arc_mru, guid, -1, FALSE, ARC_BUFC_METADATA); if (spa) break; } while (arc_mfu->arcs_lsize[ARC_BUFC_DATA]) { (void) arc_evict(arc_mfu, guid, -1, FALSE, ARC_BUFC_DATA); if (spa) break; } while (arc_mfu->arcs_lsize[ARC_BUFC_METADATA]) { (void) arc_evict(arc_mfu, guid, -1, FALSE, ARC_BUFC_METADATA); if (spa) break; } arc_evict_ghost(arc_mru_ghost, guid, -1); arc_evict_ghost(arc_mfu_ghost, guid, -1); mutex_enter(&arc_reclaim_thr_lock); arc_do_user_evicts(); mutex_exit(&arc_reclaim_thr_lock); ASSERT(spa || arc_eviction_list == NULL); } void arc_shrink(void) { + if (arc_c > arc_c_min) { uint64_t to_free; + DTRACE_PROBE4(arc__shrink, uint64_t, arc_c, uint64_t, + arc_c_min, uint64_t, arc_p, uint64_t, to_free); #ifdef _KERNEL to_free = arc_c >> arc_shrink_shift; #else to_free = arc_c >> arc_shrink_shift; #endif if (arc_c > arc_c_min + to_free) atomic_add_64(&arc_c, -to_free); else arc_c = arc_c_min; atomic_add_64(&arc_p, -(arc_p >> arc_shrink_shift)); if (arc_c > arc_size) arc_c = MAX(arc_size, arc_c_min); if (arc_p > arc_c) arc_p = (arc_c >> 1); + + DTRACE_PROBE2(arc__shrunk, uint64_t, arc_c, uint64_t, + arc_p); + ASSERT(arc_c >= arc_c_min); ASSERT((int64_t)arc_p >= 0); } - if (arc_size > arc_c) + if (arc_size > arc_c) { + DTRACE_PROBE2(arc__shrink_adjust, uint64_t, arc_size, + uint64_t, arc_c); arc_adjust(); + } } static int needfree = 0; static int arc_reclaim_needed(void) { #ifdef _KERNEL - if (needfree) + if (needfree) { + DTRACE_PROBE(arc__reclaim_needfree); return (1); + } /* * Cooperate with pagedaemon when it's time for it to scan * and reclaim some pages. */ - if (vm_paging_needed()) + if (freemem < zfs_arc_free_target) { + DTRACE_PROBE2(arc__reclaim_freemem, uint64_t, + freemem, uint64_t, zfs_arc_free_target); return (1); + } #ifdef sun /* * take 'desfree' extra pages, so we reclaim sooner, rather than later */ extra = desfree; /* * check that we're out of range of the pageout scanner. It starts to * schedule paging if freemem is less than lotsfree and needfree. * lotsfree is the high-water mark for pageout, and needfree is the * number of needed free pages. We add extra pages here to make sure * the scanner doesn't start up while we're freeing memory. */ if (freemem < lotsfree + needfree + extra) return (1); /* * check to make sure that swapfs has enough space so that anon * reservations can still succeed. anon_resvmem() checks that the * availrmem is greater than swapfs_minfree, and the number of reserved * swap pages. We also add a bit of extra here just to prevent * circumstances from getting really dire. */ if (availrmem < swapfs_minfree + swapfs_reserve + extra) return (1); -#if defined(__i386) /* + * Check that we have enough availrmem that memory locking (e.g., via + * mlock(3C) or memcntl(2)) can still succeed. (pages_pp_maximum + * stores the number of pages that cannot be locked; when availrmem + * drops below pages_pp_maximum, page locking mechanisms such as + * page_pp_lock() will fail.) + */ + if (availrmem <= pages_pp_maximum) + return (1); + +#endif /* sun */ +#if defined(__i386) || !defined(UMA_MD_SMALL_ALLOC) + /* * If we're on an i386 platform, it's possible that we'll exhaust the * kernel heap space before we ever run out of available physical * memory. Most checks of the size of the heap_area compare against * tune.t_minarmem, which is the minimum available real memory that we * can have in the system. However, this is generally fixed at 25 pages * which is so low that it's useless. In this comparison, we seek to * calculate the total heap-size, and reclaim if more than 3/4ths of the * heap is allocated. (Or, in the calculation, if less than 1/4th is * free) */ - if (btop(vmem_size(heap_arena, VMEM_FREE)) < - (btop(vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC)) >> 2)) + if (vmem_size(heap_arena, VMEM_FREE) < + (vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC) >> 2)) { + DTRACE_PROBE2(arc__reclaim_used, uint64_t, + vmem_size(heap_arena, VMEM_FREE), uint64_t, + (vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC)) >> 2); return (1); + } #endif -#else /* !sun */ - if (kmem_used() > (kmem_size() * 3) / 4) +#ifdef sun + /* + * If zio data pages are being allocated out of a separate heap segment, + * then enforce that the size of available vmem for this arena remains + * above about 1/16th free. + * + * Note: The 1/16th arena free requirement was put in place + * to aggressively evict memory from the arc in order to avoid + * memory fragmentation issues. + */ + if (zio_arena != NULL && + vmem_size(zio_arena, VMEM_FREE) < + (vmem_size(zio_arena, VMEM_ALLOC) >> 4)) return (1); #endif /* sun */ - -#else +#else /* _KERNEL */ if (spa_get_random(100) == 0) return (1); -#endif +#endif /* _KERNEL */ + DTRACE_PROBE(arc__reclaim_no); + return (0); } extern kmem_cache_t *zio_buf_cache[]; extern kmem_cache_t *zio_data_buf_cache[]; -static void +static void __noinline arc_kmem_reap_now(arc_reclaim_strategy_t strat) { size_t i; kmem_cache_t *prev_cache = NULL; kmem_cache_t *prev_data_cache = NULL; + DTRACE_PROBE(arc__kmem_reap_start); #ifdef _KERNEL if (arc_meta_used >= arc_meta_limit) { /* * We are exceeding our meta-data cache limit. * Purge some DNLC entries to release holds on meta-data. */ dnlc_reduce_cache((void *)(uintptr_t)arc_reduce_dnlc_percent); } #if defined(__i386) /* * Reclaim unused memory from all kmem caches. */ kmem_reap(); #endif #endif /* * An aggressive reclamation will shrink the cache size as well as * reap free buffers from the arc kmem caches. */ if (strat == ARC_RECLAIM_AGGR) arc_shrink(); for (i = 0; i < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT; i++) { if (zio_buf_cache[i] != prev_cache) { prev_cache = zio_buf_cache[i]; kmem_cache_reap_now(zio_buf_cache[i]); } if (zio_data_buf_cache[i] != prev_data_cache) { prev_data_cache = zio_data_buf_cache[i]; kmem_cache_reap_now(zio_data_buf_cache[i]); } } kmem_cache_reap_now(buf_cache); kmem_cache_reap_now(hdr_cache); + +#ifdef sun + /* + * Ask the vmem arena to reclaim unused memory from its + * quantum caches. + */ + if (zio_arena != NULL && strat == ARC_RECLAIM_AGGR) + vmem_qcache_reap(zio_arena); +#endif + DTRACE_PROBE(arc__kmem_reap_end); } static void arc_reclaim_thread(void *dummy __unused) { clock_t growtime = 0; arc_reclaim_strategy_t last_reclaim = ARC_RECLAIM_CONS; callb_cpr_t cpr; CALLB_CPR_INIT(&cpr, &arc_reclaim_thr_lock, callb_generic_cpr, FTAG); mutex_enter(&arc_reclaim_thr_lock); while (arc_thread_exit == 0) { if (arc_reclaim_needed()) { if (arc_no_grow) { if (last_reclaim == ARC_RECLAIM_CONS) { + DTRACE_PROBE(arc__reclaim_aggr_no_grow); last_reclaim = ARC_RECLAIM_AGGR; } else { last_reclaim = ARC_RECLAIM_CONS; } } else { arc_no_grow = TRUE; last_reclaim = ARC_RECLAIM_AGGR; + DTRACE_PROBE(arc__reclaim_aggr); membar_producer(); } /* reset the growth delay for every reclaim */ growtime = ddi_get_lbolt() + (arc_grow_retry * hz); if (needfree && last_reclaim == ARC_RECLAIM_CONS) { /* * If needfree is TRUE our vm_lowmem hook * was called and in that case we must free some * memory, so switch to aggressive mode. */ arc_no_grow = TRUE; last_reclaim = ARC_RECLAIM_AGGR; } arc_kmem_reap_now(last_reclaim); arc_warm = B_TRUE; } else if (arc_no_grow && ddi_get_lbolt() >= growtime) { arc_no_grow = FALSE; } arc_adjust(); if (arc_eviction_list != NULL) arc_do_user_evicts(); #ifdef _KERNEL if (needfree) { needfree = 0; wakeup(&needfree); } #endif /* block until needed, or one second, whichever is shorter */ CALLB_CPR_SAFE_BEGIN(&cpr); (void) cv_timedwait(&arc_reclaim_thr_cv, &arc_reclaim_thr_lock, hz); CALLB_CPR_SAFE_END(&cpr, &arc_reclaim_thr_lock); } arc_thread_exit = 0; cv_broadcast(&arc_reclaim_thr_cv); CALLB_CPR_EXIT(&cpr); /* drops arc_reclaim_thr_lock */ thread_exit(); } /* * Adapt arc info given the number of bytes we are trying to add and * the state that we are comming from. This function is only called * when we are adding new content to the cache. */ static void arc_adapt(int bytes, arc_state_t *state) { int mult; uint64_t arc_p_min = (arc_c >> arc_p_min_shift); if (state == arc_l2c_only) return; ASSERT(bytes > 0); /* * Adapt the target size of the MRU list: * - if we just hit in the MRU ghost list, then increase * the target size of the MRU list. * - if we just hit in the MFU ghost list, then increase * the target size of the MFU list by decreasing the * target size of the MRU list. */ if (state == arc_mru_ghost) { mult = ((arc_mru_ghost->arcs_size >= arc_mfu_ghost->arcs_size) ? 1 : (arc_mfu_ghost->arcs_size/arc_mru_ghost->arcs_size)); mult = MIN(mult, 10); /* avoid wild arc_p adjustment */ arc_p = MIN(arc_c - arc_p_min, arc_p + bytes * mult); } else if (state == arc_mfu_ghost) { uint64_t delta; mult = ((arc_mfu_ghost->arcs_size >= arc_mru_ghost->arcs_size) ? 1 : (arc_mru_ghost->arcs_size/arc_mfu_ghost->arcs_size)); mult = MIN(mult, 10); delta = MIN(bytes * mult, arc_p); arc_p = MAX(arc_p_min, arc_p - delta); } ASSERT((int64_t)arc_p >= 0); if (arc_reclaim_needed()) { cv_signal(&arc_reclaim_thr_cv); return; } if (arc_no_grow) return; if (arc_c >= arc_c_max) return; /* * If we're within (2 * maxblocksize) bytes of the target * cache size, increment the target cache size */ if (arc_size > arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) { + DTRACE_PROBE1(arc__inc_adapt, int, bytes); atomic_add_64(&arc_c, (int64_t)bytes); if (arc_c > arc_c_max) arc_c = arc_c_max; else if (state == arc_anon) atomic_add_64(&arc_p, (int64_t)bytes); if (arc_p > arc_c) arc_p = arc_c; } ASSERT((int64_t)arc_p >= 0); } /* * Check if the cache has reached its limits and eviction is required * prior to insert. */ static int arc_evict_needed(arc_buf_contents_t type) { if (type == ARC_BUFC_METADATA && arc_meta_used >= arc_meta_limit) return (1); -#ifdef sun -#ifdef _KERNEL - /* - * If zio data pages are being allocated out of a separate heap segment, - * then enforce that the size of available vmem for this area remains - * above about 1/32nd free. - */ - if (type == ARC_BUFC_DATA && zio_arena != NULL && - vmem_size(zio_arena, VMEM_FREE) < - (vmem_size(zio_arena, VMEM_ALLOC) >> 5)) - return (1); -#endif -#endif /* sun */ - if (arc_reclaim_needed()) return (1); return (arc_size > arc_c); } /* * The buffer, supplied as the first argument, needs a data block. * So, if we are at cache max, determine which cache should be victimized. * We have the following cases: * * 1. Insert for MRU, p > sizeof(arc_anon + arc_mru) -> * In this situation if we're out of space, but the resident size of the MFU is * under the limit, victimize the MFU cache to satisfy this insertion request. * * 2. Insert for MRU, p <= sizeof(arc_anon + arc_mru) -> * Here, we've used up all of the available space for the MRU, so we need to * evict from our own cache instead. Evict from the set of resident MRU * entries. * * 3. Insert for MFU (c - p) > sizeof(arc_mfu) -> * c minus p represents the MFU space in the cache, since p is the size of the * cache that is dedicated to the MRU. In this situation there's still space on * the MFU side, so the MRU side needs to be victimized. * * 4. Insert for MFU (c - p) < sizeof(arc_mfu) -> * MFU's resident set is consuming more space than it has been allotted. In * this situation, we must victimize our own cache, the MFU, for this insertion. */ static void arc_get_data_buf(arc_buf_t *buf) { arc_state_t *state = buf->b_hdr->b_state; uint64_t size = buf->b_hdr->b_size; arc_buf_contents_t type = buf->b_hdr->b_type; arc_adapt(size, state); /* * We have not yet reached cache maximum size, * just allocate a new buffer. */ if (!arc_evict_needed(type)) { if (type == ARC_BUFC_METADATA) { buf->b_data = zio_buf_alloc(size); arc_space_consume(size, ARC_SPACE_DATA); } else { ASSERT(type == ARC_BUFC_DATA); buf->b_data = zio_data_buf_alloc(size); ARCSTAT_INCR(arcstat_data_size, size); atomic_add_64(&arc_size, size); } goto out; } /* * If we are prefetching from the mfu ghost list, this buffer * will end up on the mru list; so steal space from there. */ if (state == arc_mfu_ghost) state = buf->b_hdr->b_flags & ARC_PREFETCH ? arc_mru : arc_mfu; else if (state == arc_mru_ghost) state = arc_mru; if (state == arc_mru || state == arc_anon) { uint64_t mru_used = arc_anon->arcs_size + arc_mru->arcs_size; state = (arc_mfu->arcs_lsize[type] >= size && arc_p > mru_used) ? arc_mfu : arc_mru; } else { /* MFU cases */ uint64_t mfu_space = arc_c - arc_p; state = (arc_mru->arcs_lsize[type] >= size && mfu_space > arc_mfu->arcs_size) ? arc_mru : arc_mfu; } if ((buf->b_data = arc_evict(state, 0, size, TRUE, type)) == NULL) { if (type == ARC_BUFC_METADATA) { buf->b_data = zio_buf_alloc(size); arc_space_consume(size, ARC_SPACE_DATA); } else { ASSERT(type == ARC_BUFC_DATA); buf->b_data = zio_data_buf_alloc(size); ARCSTAT_INCR(arcstat_data_size, size); atomic_add_64(&arc_size, size); } ARCSTAT_BUMP(arcstat_recycle_miss); } ASSERT(buf->b_data != NULL); out: /* * Update the state size. Note that ghost states have a * "ghost size" and so don't need to be updated. */ if (!GHOST_STATE(buf->b_hdr->b_state)) { arc_buf_hdr_t *hdr = buf->b_hdr; atomic_add_64(&hdr->b_state->arcs_size, size); if (list_link_active(&hdr->b_arc_node)) { ASSERT(refcount_is_zero(&hdr->b_refcnt)); atomic_add_64(&hdr->b_state->arcs_lsize[type], size); } /* * If we are growing the cache, and we are adding anonymous * data, and we have outgrown arc_p, update arc_p */ if (arc_size < arc_c && hdr->b_state == arc_anon && arc_anon->arcs_size + arc_mru->arcs_size > arc_p) arc_p = MIN(arc_c, arc_p + size); } ARCSTAT_BUMP(arcstat_allocated); } /* * This routine is called whenever a buffer is accessed. * NOTE: the hash lock is dropped in this function. */ static void arc_access(arc_buf_hdr_t *buf, kmutex_t *hash_lock) { clock_t now; ASSERT(MUTEX_HELD(hash_lock)); if (buf->b_state == arc_anon) { /* * This buffer is not in the cache, and does not * appear in our "ghost" list. Add the new buffer * to the MRU state. */ ASSERT(buf->b_arc_access == 0); buf->b_arc_access = ddi_get_lbolt(); DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, buf); arc_change_state(arc_mru, buf, hash_lock); } else if (buf->b_state == arc_mru) { now = ddi_get_lbolt(); /* * If this buffer is here because of a prefetch, then either: * - clear the flag if this is a "referencing" read * (any subsequent access will bump this into the MFU state). * or * - move the buffer to the head of the list if this is * another prefetch (to make it less likely to be evicted). */ if ((buf->b_flags & ARC_PREFETCH) != 0) { if (refcount_count(&buf->b_refcnt) == 0) { ASSERT(list_link_active(&buf->b_arc_node)); } else { buf->b_flags &= ~ARC_PREFETCH; ARCSTAT_BUMP(arcstat_mru_hits); } buf->b_arc_access = now; return; } /* * This buffer has been "accessed" only once so far, * but it is still in the cache. Move it to the MFU * state. */ if (now > buf->b_arc_access + ARC_MINTIME) { /* * More than 125ms have passed since we * instantiated this buffer. Move it to the * most frequently used state. */ buf->b_arc_access = now; DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf); arc_change_state(arc_mfu, buf, hash_lock); } ARCSTAT_BUMP(arcstat_mru_hits); } else if (buf->b_state == arc_mru_ghost) { arc_state_t *new_state; /* * This buffer has been "accessed" recently, but * was evicted from the cache. Move it to the * MFU state. */ if (buf->b_flags & ARC_PREFETCH) { new_state = arc_mru; if (refcount_count(&buf->b_refcnt) > 0) buf->b_flags &= ~ARC_PREFETCH; DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, buf); } else { new_state = arc_mfu; DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf); } buf->b_arc_access = ddi_get_lbolt(); arc_change_state(new_state, buf, hash_lock); ARCSTAT_BUMP(arcstat_mru_ghost_hits); } else if (buf->b_state == arc_mfu) { /* * This buffer has been accessed more than once and is * still in the cache. Keep it in the MFU state. * * NOTE: an add_reference() that occurred when we did * the arc_read() will have kicked this off the list. * If it was a prefetch, we will explicitly move it to * the head of the list now. */ if ((buf->b_flags & ARC_PREFETCH) != 0) { ASSERT(refcount_count(&buf->b_refcnt) == 0); ASSERT(list_link_active(&buf->b_arc_node)); } ARCSTAT_BUMP(arcstat_mfu_hits); buf->b_arc_access = ddi_get_lbolt(); } else if (buf->b_state == arc_mfu_ghost) { arc_state_t *new_state = arc_mfu; /* * This buffer has been accessed more than once but has * been evicted from the cache. Move it back to the * MFU state. */ if (buf->b_flags & ARC_PREFETCH) { /* * This is a prefetch access... * move this block back to the MRU state. */ ASSERT0(refcount_count(&buf->b_refcnt)); new_state = arc_mru; } buf->b_arc_access = ddi_get_lbolt(); DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf); arc_change_state(new_state, buf, hash_lock); ARCSTAT_BUMP(arcstat_mfu_ghost_hits); } else if (buf->b_state == arc_l2c_only) { /* * This buffer is on the 2nd Level ARC. */ buf->b_arc_access = ddi_get_lbolt(); DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf); arc_change_state(arc_mfu, buf, hash_lock); } else { ASSERT(!"invalid arc state"); } } /* a generic arc_done_func_t which you can use */ /* ARGSUSED */ void arc_bcopy_func(zio_t *zio, arc_buf_t *buf, void *arg) { if (zio == NULL || zio->io_error == 0) bcopy(buf->b_data, arg, buf->b_hdr->b_size); VERIFY(arc_buf_remove_ref(buf, arg)); } /* a generic arc_done_func_t */ void arc_getbuf_func(zio_t *zio, arc_buf_t *buf, void *arg) { arc_buf_t **bufp = arg; if (zio && zio->io_error) { VERIFY(arc_buf_remove_ref(buf, arg)); *bufp = NULL; } else { *bufp = buf; ASSERT(buf->b_data); } } static void arc_read_done(zio_t *zio) { arc_buf_hdr_t *hdr; arc_buf_t *buf; arc_buf_t *abuf; /* buffer we're assigning to callback */ kmutex_t *hash_lock = NULL; arc_callback_t *callback_list, *acb; int freeable = FALSE; buf = zio->io_private; hdr = buf->b_hdr; /* * The hdr was inserted into hash-table and removed from lists * prior to starting I/O. We should find this header, since * it's in the hash table, and it should be legit since it's * not possible to evict it during the I/O. The only possible * reason for it not to be found is if we were freed during the * read. */ if (HDR_IN_HASH_TABLE(hdr)) { ASSERT3U(hdr->b_birth, ==, BP_PHYSICAL_BIRTH(zio->io_bp)); ASSERT3U(hdr->b_dva.dva_word[0], ==, BP_IDENTITY(zio->io_bp)->dva_word[0]); ASSERT3U(hdr->b_dva.dva_word[1], ==, BP_IDENTITY(zio->io_bp)->dva_word[1]); arc_buf_hdr_t *found = buf_hash_find(hdr->b_spa, zio->io_bp, &hash_lock); ASSERT((found == NULL && HDR_FREED_IN_READ(hdr) && hash_lock == NULL) || (found == hdr && DVA_EQUAL(&hdr->b_dva, BP_IDENTITY(zio->io_bp))) || (found == hdr && HDR_L2_READING(hdr))); } hdr->b_flags &= ~ARC_L2_EVICTED; if (l2arc_noprefetch && (hdr->b_flags & ARC_PREFETCH)) hdr->b_flags &= ~ARC_L2CACHE; /* byteswap if necessary */ callback_list = hdr->b_acb; ASSERT(callback_list != NULL); if (BP_SHOULD_BYTESWAP(zio->io_bp) && zio->io_error == 0) { dmu_object_byteswap_t bswap = DMU_OT_BYTESWAP(BP_GET_TYPE(zio->io_bp)); arc_byteswap_func_t *func = BP_GET_LEVEL(zio->io_bp) > 0 ? byteswap_uint64_array : dmu_ot_byteswap[bswap].ob_func; func(buf->b_data, hdr->b_size); } arc_cksum_compute(buf, B_FALSE); #ifdef illumos arc_buf_watch(buf); #endif /* illumos */ if (hash_lock && zio->io_error == 0 && hdr->b_state == arc_anon) { /* * Only call arc_access on anonymous buffers. This is because * if we've issued an I/O for an evicted buffer, we've already * called arc_access (to prevent any simultaneous readers from * getting confused). */ arc_access(hdr, hash_lock); } /* create copies of the data buffer for the callers */ abuf = buf; for (acb = callback_list; acb; acb = acb->acb_next) { if (acb->acb_done) { if (abuf == NULL) { ARCSTAT_BUMP(arcstat_duplicate_reads); abuf = arc_buf_clone(buf); } acb->acb_buf = abuf; abuf = NULL; } } hdr->b_acb = NULL; hdr->b_flags &= ~ARC_IO_IN_PROGRESS; ASSERT(!HDR_BUF_AVAILABLE(hdr)); if (abuf == buf) { ASSERT(buf->b_efunc == NULL); ASSERT(hdr->b_datacnt == 1); hdr->b_flags |= ARC_BUF_AVAILABLE; } ASSERT(refcount_is_zero(&hdr->b_refcnt) || callback_list != NULL); if (zio->io_error != 0) { hdr->b_flags |= ARC_IO_ERROR; if (hdr->b_state != arc_anon) arc_change_state(arc_anon, hdr, hash_lock); if (HDR_IN_HASH_TABLE(hdr)) buf_hash_remove(hdr); freeable = refcount_is_zero(&hdr->b_refcnt); } /* * Broadcast before we drop the hash_lock to avoid the possibility * that the hdr (and hence the cv) might be freed before we get to * the cv_broadcast(). */ cv_broadcast(&hdr->b_cv); if (hash_lock) { mutex_exit(hash_lock); } else { /* * This block was freed while we waited for the read to * complete. It has been removed from the hash table and * moved to the anonymous state (so that it won't show up * in the cache). */ ASSERT3P(hdr->b_state, ==, arc_anon); freeable = refcount_is_zero(&hdr->b_refcnt); } /* execute each callback and free its structure */ while ((acb = callback_list) != NULL) { if (acb->acb_done) acb->acb_done(zio, acb->acb_buf, acb->acb_private); if (acb->acb_zio_dummy != NULL) { acb->acb_zio_dummy->io_error = zio->io_error; zio_nowait(acb->acb_zio_dummy); } callback_list = acb->acb_next; kmem_free(acb, sizeof (arc_callback_t)); } if (freeable) arc_hdr_destroy(hdr); } /* * "Read" the block block at the specified DVA (in bp) via the * cache. If the block is found in the cache, invoke the provided * callback immediately and return. Note that the `zio' parameter * in the callback will be NULL in this case, since no IO was * required. If the block is not in the cache pass the read request * on to the spa with a substitute callback function, so that the * requested block will be added to the cache. * * If a read request arrives for a block that has a read in-progress, * either wait for the in-progress read to complete (and return the * results); or, if this is a read with a "done" func, add a record * to the read to invoke the "done" func when the read completes, * and return; or just return. * * arc_read_done() will invoke all the requested "done" functions * for readers of this block. */ int arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp, arc_done_func_t *done, void *private, zio_priority_t priority, int zio_flags, uint32_t *arc_flags, const zbookmark_phys_t *zb) { arc_buf_hdr_t *hdr = NULL; arc_buf_t *buf = NULL; kmutex_t *hash_lock = NULL; zio_t *rzio; uint64_t guid = spa_load_guid(spa); ASSERT(!BP_IS_EMBEDDED(bp) || BPE_GET_ETYPE(bp) == BP_EMBEDDED_TYPE_DATA); top: if (!BP_IS_EMBEDDED(bp)) { /* * Embedded BP's have no DVA and require no I/O to "read". * Create an anonymous arc buf to back it. */ hdr = buf_hash_find(guid, bp, &hash_lock); } if (hdr != NULL && hdr->b_datacnt > 0) { *arc_flags |= ARC_CACHED; if (HDR_IO_IN_PROGRESS(hdr)) { if (*arc_flags & ARC_WAIT) { cv_wait(&hdr->b_cv, hash_lock); mutex_exit(hash_lock); goto top; } ASSERT(*arc_flags & ARC_NOWAIT); if (done) { arc_callback_t *acb = NULL; acb = kmem_zalloc(sizeof (arc_callback_t), KM_SLEEP); acb->acb_done = done; acb->acb_private = private; if (pio != NULL) acb->acb_zio_dummy = zio_null(pio, spa, NULL, NULL, NULL, zio_flags); ASSERT(acb->acb_done != NULL); acb->acb_next = hdr->b_acb; hdr->b_acb = acb; add_reference(hdr, hash_lock, private); mutex_exit(hash_lock); return (0); } mutex_exit(hash_lock); return (0); } ASSERT(hdr->b_state == arc_mru || hdr->b_state == arc_mfu); if (done) { add_reference(hdr, hash_lock, private); /* * If this block is already in use, create a new * copy of the data so that we will be guaranteed * that arc_release() will always succeed. */ buf = hdr->b_buf; ASSERT(buf); ASSERT(buf->b_data); if (HDR_BUF_AVAILABLE(hdr)) { ASSERT(buf->b_efunc == NULL); hdr->b_flags &= ~ARC_BUF_AVAILABLE; } else { buf = arc_buf_clone(buf); } } else if (*arc_flags & ARC_PREFETCH && refcount_count(&hdr->b_refcnt) == 0) { hdr->b_flags |= ARC_PREFETCH; } DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr); arc_access(hdr, hash_lock); if (*arc_flags & ARC_L2CACHE) hdr->b_flags |= ARC_L2CACHE; if (*arc_flags & ARC_L2COMPRESS) hdr->b_flags |= ARC_L2COMPRESS; mutex_exit(hash_lock); ARCSTAT_BUMP(arcstat_hits); ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH), demand, prefetch, hdr->b_type != ARC_BUFC_METADATA, data, metadata, hits); if (done) done(NULL, buf, private); } else { uint64_t size = BP_GET_LSIZE(bp); arc_callback_t *acb; vdev_t *vd = NULL; uint64_t addr = 0; boolean_t devw = B_FALSE; enum zio_compress b_compress = ZIO_COMPRESS_OFF; uint64_t b_asize = 0; if (hdr == NULL) { /* this block is not in the cache */ arc_buf_hdr_t *exists = NULL; arc_buf_contents_t type = BP_GET_BUFC_TYPE(bp); buf = arc_buf_alloc(spa, size, private, type); hdr = buf->b_hdr; if (!BP_IS_EMBEDDED(bp)) { hdr->b_dva = *BP_IDENTITY(bp); hdr->b_birth = BP_PHYSICAL_BIRTH(bp); hdr->b_cksum0 = bp->blk_cksum.zc_word[0]; exists = buf_hash_insert(hdr, &hash_lock); } if (exists != NULL) { /* somebody beat us to the hash insert */ mutex_exit(hash_lock); buf_discard_identity(hdr); (void) arc_buf_remove_ref(buf, private); goto top; /* restart the IO request */ } /* if this is a prefetch, we don't have a reference */ if (*arc_flags & ARC_PREFETCH) { (void) remove_reference(hdr, hash_lock, private); hdr->b_flags |= ARC_PREFETCH; } if (*arc_flags & ARC_L2CACHE) hdr->b_flags |= ARC_L2CACHE; if (*arc_flags & ARC_L2COMPRESS) hdr->b_flags |= ARC_L2COMPRESS; if (BP_GET_LEVEL(bp) > 0) hdr->b_flags |= ARC_INDIRECT; } else { /* this block is in the ghost cache */ ASSERT(GHOST_STATE(hdr->b_state)); ASSERT(!HDR_IO_IN_PROGRESS(hdr)); ASSERT0(refcount_count(&hdr->b_refcnt)); ASSERT(hdr->b_buf == NULL); /* if this is a prefetch, we don't have a reference */ if (*arc_flags & ARC_PREFETCH) hdr->b_flags |= ARC_PREFETCH; else add_reference(hdr, hash_lock, private); if (*arc_flags & ARC_L2CACHE) hdr->b_flags |= ARC_L2CACHE; if (*arc_flags & ARC_L2COMPRESS) hdr->b_flags |= ARC_L2COMPRESS; buf = kmem_cache_alloc(buf_cache, KM_PUSHPAGE); buf->b_hdr = hdr; buf->b_data = NULL; buf->b_efunc = NULL; buf->b_private = NULL; buf->b_next = NULL; hdr->b_buf = buf; ASSERT(hdr->b_datacnt == 0); hdr->b_datacnt = 1; arc_get_data_buf(buf); arc_access(hdr, hash_lock); } ASSERT(!GHOST_STATE(hdr->b_state)); acb = kmem_zalloc(sizeof (arc_callback_t), KM_SLEEP); acb->acb_done = done; acb->acb_private = private; ASSERT(hdr->b_acb == NULL); hdr->b_acb = acb; hdr->b_flags |= ARC_IO_IN_PROGRESS; if (hdr->b_l2hdr != NULL && (vd = hdr->b_l2hdr->b_dev->l2ad_vdev) != NULL) { devw = hdr->b_l2hdr->b_dev->l2ad_writing; addr = hdr->b_l2hdr->b_daddr; b_compress = hdr->b_l2hdr->b_compress; b_asize = hdr->b_l2hdr->b_asize; /* * Lock out device removal. */ if (vdev_is_dead(vd) || !spa_config_tryenter(spa, SCL_L2ARC, vd, RW_READER)) vd = NULL; } if (hash_lock != NULL) mutex_exit(hash_lock); /* * At this point, we have a level 1 cache miss. Try again in * L2ARC if possible. */ ASSERT3U(hdr->b_size, ==, size); DTRACE_PROBE4(arc__miss, arc_buf_hdr_t *, hdr, blkptr_t *, bp, uint64_t, size, zbookmark_phys_t *, zb); ARCSTAT_BUMP(arcstat_misses); ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH), demand, prefetch, hdr->b_type != ARC_BUFC_METADATA, data, metadata, misses); #ifdef _KERNEL curthread->td_ru.ru_inblock++; #endif if (vd != NULL && l2arc_ndev != 0 && !(l2arc_norw && devw)) { /* * Read from the L2ARC if the following are true: * 1. The L2ARC vdev was previously cached. * 2. This buffer still has L2ARC metadata. * 3. This buffer isn't currently writing to the L2ARC. * 4. The L2ARC entry wasn't evicted, which may * also have invalidated the vdev. * 5. This isn't prefetch and l2arc_noprefetch is set. */ if (hdr->b_l2hdr != NULL && !HDR_L2_WRITING(hdr) && !HDR_L2_EVICTED(hdr) && !(l2arc_noprefetch && HDR_PREFETCH(hdr))) { l2arc_read_callback_t *cb; DTRACE_PROBE1(l2arc__hit, arc_buf_hdr_t *, hdr); ARCSTAT_BUMP(arcstat_l2_hits); cb = kmem_zalloc(sizeof (l2arc_read_callback_t), KM_SLEEP); cb->l2rcb_buf = buf; cb->l2rcb_spa = spa; cb->l2rcb_bp = *bp; cb->l2rcb_zb = *zb; cb->l2rcb_flags = zio_flags; cb->l2rcb_compress = b_compress; ASSERT(addr >= VDEV_LABEL_START_SIZE && addr + size < vd->vdev_psize - VDEV_LABEL_END_SIZE); /* * l2arc read. The SCL_L2ARC lock will be * released by l2arc_read_done(). * Issue a null zio if the underlying buffer * was squashed to zero size by compression. */ if (b_compress == ZIO_COMPRESS_EMPTY) { rzio = zio_null(pio, spa, vd, l2arc_read_done, cb, zio_flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY); } else { rzio = zio_read_phys(pio, vd, addr, b_asize, buf->b_data, ZIO_CHECKSUM_OFF, l2arc_read_done, cb, priority, zio_flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_PROPAGATE | ZIO_FLAG_DONT_RETRY, B_FALSE); } DTRACE_PROBE2(l2arc__read, vdev_t *, vd, zio_t *, rzio); ARCSTAT_INCR(arcstat_l2_read_bytes, b_asize); if (*arc_flags & ARC_NOWAIT) { zio_nowait(rzio); return (0); } ASSERT(*arc_flags & ARC_WAIT); if (zio_wait(rzio) == 0) return (0); /* l2arc read error; goto zio_read() */ } else { DTRACE_PROBE1(l2arc__miss, arc_buf_hdr_t *, hdr); ARCSTAT_BUMP(arcstat_l2_misses); if (HDR_L2_WRITING(hdr)) ARCSTAT_BUMP(arcstat_l2_rw_clash); spa_config_exit(spa, SCL_L2ARC, vd); } } else { if (vd != NULL) spa_config_exit(spa, SCL_L2ARC, vd); if (l2arc_ndev != 0) { DTRACE_PROBE1(l2arc__miss, arc_buf_hdr_t *, hdr); ARCSTAT_BUMP(arcstat_l2_misses); } } rzio = zio_read(pio, spa, bp, buf->b_data, size, arc_read_done, buf, priority, zio_flags, zb); if (*arc_flags & ARC_WAIT) return (zio_wait(rzio)); ASSERT(*arc_flags & ARC_NOWAIT); zio_nowait(rzio); } return (0); } void arc_set_callback(arc_buf_t *buf, arc_evict_func_t *func, void *private) { ASSERT(buf->b_hdr != NULL); ASSERT(buf->b_hdr->b_state != arc_anon); ASSERT(!refcount_is_zero(&buf->b_hdr->b_refcnt) || func == NULL); ASSERT(buf->b_efunc == NULL); ASSERT(!HDR_BUF_AVAILABLE(buf->b_hdr)); buf->b_efunc = func; buf->b_private = private; } /* * Notify the arc that a block was freed, and thus will never be used again. */ void arc_freed(spa_t *spa, const blkptr_t *bp) { arc_buf_hdr_t *hdr; kmutex_t *hash_lock; uint64_t guid = spa_load_guid(spa); ASSERT(!BP_IS_EMBEDDED(bp)); hdr = buf_hash_find(guid, bp, &hash_lock); if (hdr == NULL) return; if (HDR_BUF_AVAILABLE(hdr)) { arc_buf_t *buf = hdr->b_buf; add_reference(hdr, hash_lock, FTAG); hdr->b_flags &= ~ARC_BUF_AVAILABLE; mutex_exit(hash_lock); arc_release(buf, FTAG); (void) arc_buf_remove_ref(buf, FTAG); } else { mutex_exit(hash_lock); } } /* * Clear the user eviction callback set by arc_set_callback(), first calling * it if it exists. Because the presence of a callback keeps an arc_buf cached * clearing the callback may result in the arc_buf being destroyed. However, * it will not result in the *last* arc_buf being destroyed, hence the data * will remain cached in the ARC. We make a copy of the arc buffer here so * that we can process the callback without holding any locks. * * It's possible that the callback is already in the process of being cleared * by another thread. In this case we can not clear the callback. * * Returns B_TRUE if the callback was successfully called and cleared. */ boolean_t arc_clear_callback(arc_buf_t *buf) { arc_buf_hdr_t *hdr; kmutex_t *hash_lock; arc_evict_func_t *efunc = buf->b_efunc; void *private = buf->b_private; list_t *list, *evicted_list; kmutex_t *lock, *evicted_lock; mutex_enter(&buf->b_evict_lock); hdr = buf->b_hdr; if (hdr == NULL) { /* * We are in arc_do_user_evicts(). */ ASSERT(buf->b_data == NULL); mutex_exit(&buf->b_evict_lock); return (B_FALSE); } else if (buf->b_data == NULL) { /* * We are on the eviction list; process this buffer now * but let arc_do_user_evicts() do the reaping. */ buf->b_efunc = NULL; mutex_exit(&buf->b_evict_lock); VERIFY0(efunc(private)); return (B_TRUE); } hash_lock = HDR_LOCK(hdr); mutex_enter(hash_lock); hdr = buf->b_hdr; ASSERT3P(hash_lock, ==, HDR_LOCK(hdr)); ASSERT3U(refcount_count(&hdr->b_refcnt), <, hdr->b_datacnt); ASSERT(hdr->b_state == arc_mru || hdr->b_state == arc_mfu); buf->b_efunc = NULL; buf->b_private = NULL; if (hdr->b_datacnt > 1) { mutex_exit(&buf->b_evict_lock); arc_buf_destroy(buf, FALSE, TRUE); } else { ASSERT(buf == hdr->b_buf); hdr->b_flags |= ARC_BUF_AVAILABLE; mutex_exit(&buf->b_evict_lock); } mutex_exit(hash_lock); VERIFY0(efunc(private)); return (B_TRUE); } /* * Release this buffer from the cache, making it an anonymous buffer. This * must be done after a read and prior to modifying the buffer contents. * If the buffer has more than one reference, we must make * a new hdr for the buffer. */ void arc_release(arc_buf_t *buf, void *tag) { arc_buf_hdr_t *hdr; kmutex_t *hash_lock = NULL; l2arc_buf_hdr_t *l2hdr; uint64_t buf_size; /* * It would be nice to assert that if it's DMU metadata (level > * 0 || it's the dnode file), then it must be syncing context. * But we don't know that information at this level. */ mutex_enter(&buf->b_evict_lock); hdr = buf->b_hdr; /* this buffer is not on any list */ ASSERT(refcount_count(&hdr->b_refcnt) > 0); if (hdr->b_state == arc_anon) { /* this buffer is already released */ ASSERT(buf->b_efunc == NULL); } else { hash_lock = HDR_LOCK(hdr); mutex_enter(hash_lock); hdr = buf->b_hdr; ASSERT3P(hash_lock, ==, HDR_LOCK(hdr)); } l2hdr = hdr->b_l2hdr; if (l2hdr) { mutex_enter(&l2arc_buflist_mtx); hdr->b_l2hdr = NULL; list_remove(l2hdr->b_dev->l2ad_buflist, hdr); } buf_size = hdr->b_size; /* * Do we have more than one buf? */ if (hdr->b_datacnt > 1) { arc_buf_hdr_t *nhdr; arc_buf_t **bufp; uint64_t blksz = hdr->b_size; uint64_t spa = hdr->b_spa; arc_buf_contents_t type = hdr->b_type; uint32_t flags = hdr->b_flags; ASSERT(hdr->b_buf != buf || buf->b_next != NULL); /* * Pull the data off of this hdr and attach it to * a new anonymous hdr. */ (void) remove_reference(hdr, hash_lock, tag); bufp = &hdr->b_buf; while (*bufp != buf) bufp = &(*bufp)->b_next; *bufp = buf->b_next; buf->b_next = NULL; ASSERT3U(hdr->b_state->arcs_size, >=, hdr->b_size); atomic_add_64(&hdr->b_state->arcs_size, -hdr->b_size); if (refcount_is_zero(&hdr->b_refcnt)) { uint64_t *size = &hdr->b_state->arcs_lsize[hdr->b_type]; ASSERT3U(*size, >=, hdr->b_size); atomic_add_64(size, -hdr->b_size); } /* * We're releasing a duplicate user data buffer, update * our statistics accordingly. */ if (hdr->b_type == ARC_BUFC_DATA) { ARCSTAT_BUMPDOWN(arcstat_duplicate_buffers); ARCSTAT_INCR(arcstat_duplicate_buffers_size, -hdr->b_size); } hdr->b_datacnt -= 1; arc_cksum_verify(buf); #ifdef illumos arc_buf_unwatch(buf); #endif /* illumos */ mutex_exit(hash_lock); nhdr = kmem_cache_alloc(hdr_cache, KM_PUSHPAGE); nhdr->b_size = blksz; nhdr->b_spa = spa; nhdr->b_type = type; nhdr->b_buf = buf; nhdr->b_state = arc_anon; nhdr->b_arc_access = 0; nhdr->b_flags = flags & ARC_L2_WRITING; nhdr->b_l2hdr = NULL; nhdr->b_datacnt = 1; nhdr->b_freeze_cksum = NULL; (void) refcount_add(&nhdr->b_refcnt, tag); buf->b_hdr = nhdr; mutex_exit(&buf->b_evict_lock); atomic_add_64(&arc_anon->arcs_size, blksz); } else { mutex_exit(&buf->b_evict_lock); ASSERT(refcount_count(&hdr->b_refcnt) == 1); ASSERT(!list_link_active(&hdr->b_arc_node)); ASSERT(!HDR_IO_IN_PROGRESS(hdr)); if (hdr->b_state != arc_anon) arc_change_state(arc_anon, hdr, hash_lock); hdr->b_arc_access = 0; if (hash_lock) mutex_exit(hash_lock); buf_discard_identity(hdr); arc_buf_thaw(buf); } buf->b_efunc = NULL; buf->b_private = NULL; if (l2hdr) { ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize); vdev_space_update(l2hdr->b_dev->l2ad_vdev, -l2hdr->b_asize, 0, 0); trim_map_free(l2hdr->b_dev->l2ad_vdev, l2hdr->b_daddr, hdr->b_size, 0); kmem_free(l2hdr, sizeof (l2arc_buf_hdr_t)); ARCSTAT_INCR(arcstat_l2_size, -buf_size); mutex_exit(&l2arc_buflist_mtx); } } int arc_released(arc_buf_t *buf) { int released; mutex_enter(&buf->b_evict_lock); released = (buf->b_data != NULL && buf->b_hdr->b_state == arc_anon); mutex_exit(&buf->b_evict_lock); return (released); } #ifdef ZFS_DEBUG int arc_referenced(arc_buf_t *buf) { int referenced; mutex_enter(&buf->b_evict_lock); referenced = (refcount_count(&buf->b_hdr->b_refcnt)); mutex_exit(&buf->b_evict_lock); return (referenced); } #endif static void arc_write_ready(zio_t *zio) { arc_write_callback_t *callback = zio->io_private; arc_buf_t *buf = callback->awcb_buf; arc_buf_hdr_t *hdr = buf->b_hdr; ASSERT(!refcount_is_zero(&buf->b_hdr->b_refcnt)); callback->awcb_ready(zio, buf, callback->awcb_private); /* * If the IO is already in progress, then this is a re-write * attempt, so we need to thaw and re-compute the cksum. * It is the responsibility of the callback to handle the * accounting for any re-write attempt. */ if (HDR_IO_IN_PROGRESS(hdr)) { mutex_enter(&hdr->b_freeze_lock); if (hdr->b_freeze_cksum != NULL) { kmem_free(hdr->b_freeze_cksum, sizeof (zio_cksum_t)); hdr->b_freeze_cksum = NULL; } mutex_exit(&hdr->b_freeze_lock); } arc_cksum_compute(buf, B_FALSE); hdr->b_flags |= ARC_IO_IN_PROGRESS; } /* * The SPA calls this callback for each physical write that happens on behalf * of a logical write. See the comment in dbuf_write_physdone() for details. */ static void arc_write_physdone(zio_t *zio) { arc_write_callback_t *cb = zio->io_private; if (cb->awcb_physdone != NULL) cb->awcb_physdone(zio, cb->awcb_buf, cb->awcb_private); } static void arc_write_done(zio_t *zio) { arc_write_callback_t *callback = zio->io_private; arc_buf_t *buf = callback->awcb_buf; arc_buf_hdr_t *hdr = buf->b_hdr; ASSERT(hdr->b_acb == NULL); if (zio->io_error == 0) { if (BP_IS_HOLE(zio->io_bp) || BP_IS_EMBEDDED(zio->io_bp)) { buf_discard_identity(hdr); } else { hdr->b_dva = *BP_IDENTITY(zio->io_bp); hdr->b_birth = BP_PHYSICAL_BIRTH(zio->io_bp); hdr->b_cksum0 = zio->io_bp->blk_cksum.zc_word[0]; } } else { ASSERT(BUF_EMPTY(hdr)); } /* * If the block to be written was all-zero or compressed enough to be * embedded in the BP, no write was performed so there will be no * dva/birth/checksum. The buffer must therefore remain anonymous * (and uncached). */ if (!BUF_EMPTY(hdr)) { arc_buf_hdr_t *exists; kmutex_t *hash_lock; ASSERT(zio->io_error == 0); arc_cksum_verify(buf); exists = buf_hash_insert(hdr, &hash_lock); if (exists) { /* * This can only happen if we overwrite for * sync-to-convergence, because we remove * buffers from the hash table when we arc_free(). */ if (zio->io_flags & ZIO_FLAG_IO_REWRITE) { if (!BP_EQUAL(&zio->io_bp_orig, zio->io_bp)) panic("bad overwrite, hdr=%p exists=%p", (void *)hdr, (void *)exists); ASSERT(refcount_is_zero(&exists->b_refcnt)); arc_change_state(arc_anon, exists, hash_lock); mutex_exit(hash_lock); arc_hdr_destroy(exists); exists = buf_hash_insert(hdr, &hash_lock); ASSERT3P(exists, ==, NULL); } else if (zio->io_flags & ZIO_FLAG_NOPWRITE) { /* nopwrite */ ASSERT(zio->io_prop.zp_nopwrite); if (!BP_EQUAL(&zio->io_bp_orig, zio->io_bp)) panic("bad nopwrite, hdr=%p exists=%p", (void *)hdr, (void *)exists); } else { /* Dedup */ ASSERT(hdr->b_datacnt == 1); ASSERT(hdr->b_state == arc_anon); ASSERT(BP_GET_DEDUP(zio->io_bp)); ASSERT(BP_GET_LEVEL(zio->io_bp) == 0); } } hdr->b_flags &= ~ARC_IO_IN_PROGRESS; /* if it's not anon, we are doing a scrub */ if (!exists && hdr->b_state == arc_anon) arc_access(hdr, hash_lock); mutex_exit(hash_lock); } else { hdr->b_flags &= ~ARC_IO_IN_PROGRESS; } ASSERT(!refcount_is_zero(&hdr->b_refcnt)); callback->awcb_done(zio, buf, callback->awcb_private); kmem_free(callback, sizeof (arc_write_callback_t)); } zio_t * arc_write(zio_t *pio, spa_t *spa, uint64_t txg, blkptr_t *bp, arc_buf_t *buf, boolean_t l2arc, boolean_t l2arc_compress, const zio_prop_t *zp, arc_done_func_t *ready, arc_done_func_t *physdone, arc_done_func_t *done, void *private, zio_priority_t priority, int zio_flags, const zbookmark_phys_t *zb) { arc_buf_hdr_t *hdr = buf->b_hdr; arc_write_callback_t *callback; zio_t *zio; ASSERT(ready != NULL); ASSERT(done != NULL); ASSERT(!HDR_IO_ERROR(hdr)); ASSERT((hdr->b_flags & ARC_IO_IN_PROGRESS) == 0); ASSERT(hdr->b_acb == NULL); if (l2arc) hdr->b_flags |= ARC_L2CACHE; if (l2arc_compress) hdr->b_flags |= ARC_L2COMPRESS; callback = kmem_zalloc(sizeof (arc_write_callback_t), KM_SLEEP); callback->awcb_ready = ready; callback->awcb_physdone = physdone; callback->awcb_done = done; callback->awcb_private = private; callback->awcb_buf = buf; zio = zio_write(pio, spa, txg, bp, buf->b_data, hdr->b_size, zp, arc_write_ready, arc_write_physdone, arc_write_done, callback, priority, zio_flags, zb); return (zio); } static int arc_memory_throttle(uint64_t reserve, uint64_t txg) { #ifdef _KERNEL - uint64_t available_memory = - ptoa((uintmax_t)cnt.v_free_count + cnt.v_cache_count); + uint64_t available_memory = ptob(freemem); static uint64_t page_load = 0; static uint64_t last_txg = 0; -#ifdef sun -#if defined(__i386) +#if defined(__i386) || !defined(UMA_MD_SMALL_ALLOC) available_memory = - MIN(available_memory, vmem_size(heap_arena, VMEM_FREE)); + MIN(available_memory, ptob(vmem_size(heap_arena, VMEM_FREE))); #endif -#endif /* sun */ - if (cnt.v_free_count + cnt.v_cache_count > - (uint64_t)physmem * arc_lotsfree_percent / 100) + if (freemem > (uint64_t)physmem * arc_lotsfree_percent / 100) return (0); if (txg > last_txg) { last_txg = txg; page_load = 0; } /* * If we are in pageout, we know that memory is already tight, * the arc is already going to be evicting, so we just want to * continue to let page writes occur as quickly as possible. */ if (curproc == pageproc) { - if (page_load > available_memory / 4) + if (page_load > MAX(ptob(minfree), available_memory) / 4) return (SET_ERROR(ERESTART)); /* Note: reserve is inflated, so we deflate */ page_load += reserve / 8; return (0); } else if (page_load > 0 && arc_reclaim_needed()) { /* memory is low, delay before restarting */ ARCSTAT_INCR(arcstat_memory_throttle_count, 1); return (SET_ERROR(EAGAIN)); } page_load = 0; #endif return (0); } void arc_tempreserve_clear(uint64_t reserve) { atomic_add_64(&arc_tempreserve, -reserve); ASSERT((int64_t)arc_tempreserve >= 0); } int arc_tempreserve_space(uint64_t reserve, uint64_t txg) { int error; uint64_t anon_size; - if (reserve > arc_c/4 && !arc_no_grow) + if (reserve > arc_c/4 && !arc_no_grow) { arc_c = MIN(arc_c_max, reserve * 4); + DTRACE_PROBE1(arc__set_reserve, uint64_t, arc_c); + } if (reserve > arc_c) return (SET_ERROR(ENOMEM)); /* * Don't count loaned bufs as in flight dirty data to prevent long * network delays from blocking transactions that are ready to be * assigned to a txg. */ anon_size = MAX((int64_t)(arc_anon->arcs_size - arc_loaned_bytes), 0); /* * Writes will, almost always, require additional memory allocations * in order to compress/encrypt/etc the data. We therefore need to * make sure that there is sufficient available memory for this. */ error = arc_memory_throttle(reserve, txg); if (error != 0) return (error); /* * Throttle writes when the amount of dirty data in the cache * gets too large. We try to keep the cache less than half full * of dirty blocks so that our sync times don't grow too large. * Note: if two requests come in concurrently, we might let them * both succeed, when one of them should fail. Not a huge deal. */ if (reserve + arc_tempreserve + anon_size > arc_c / 2 && anon_size > arc_c / 4) { dprintf("failing, arc_tempreserve=%lluK anon_meta=%lluK " "anon_data=%lluK tempreserve=%lluK arc_c=%lluK\n", arc_tempreserve>>10, arc_anon->arcs_lsize[ARC_BUFC_METADATA]>>10, arc_anon->arcs_lsize[ARC_BUFC_DATA]>>10, reserve>>10, arc_c>>10); return (SET_ERROR(ERESTART)); } atomic_add_64(&arc_tempreserve, reserve); return (0); } static kmutex_t arc_lowmem_lock; #ifdef _KERNEL static eventhandler_tag arc_event_lowmem = NULL; static void arc_lowmem(void *arg __unused, int howto __unused) { /* Serialize access via arc_lowmem_lock. */ mutex_enter(&arc_lowmem_lock); mutex_enter(&arc_reclaim_thr_lock); needfree = 1; + DTRACE_PROBE(arc__needfree); cv_signal(&arc_reclaim_thr_cv); /* * It is unsafe to block here in arbitrary threads, because we can come * here from ARC itself and may hold ARC locks and thus risk a deadlock * with ARC reclaim thread. */ if (curproc == pageproc) { while (needfree) msleep(&needfree, &arc_reclaim_thr_lock, 0, "zfs:lowmem", 0); } mutex_exit(&arc_reclaim_thr_lock); mutex_exit(&arc_lowmem_lock); } #endif void arc_init(void) { int i, prefetch_tunable_set = 0; mutex_init(&arc_reclaim_thr_lock, NULL, MUTEX_DEFAULT, NULL); cv_init(&arc_reclaim_thr_cv, NULL, CV_DEFAULT, NULL); mutex_init(&arc_lowmem_lock, NULL, MUTEX_DEFAULT, NULL); /* Convert seconds to clock ticks */ arc_min_prefetch_lifespan = 1 * hz; /* Start out with 1/8 of all memory */ arc_c = kmem_size() / 8; #ifdef sun #ifdef _KERNEL /* * On architectures where the physical memory can be larger * than the addressable space (intel in 32-bit mode), we may * need to limit the cache to 1/8 of VM size. */ arc_c = MIN(arc_c, vmem_size(heap_arena, VMEM_ALLOC | VMEM_FREE) / 8); #endif #endif /* sun */ /* set min cache to 1/32 of all memory, or 16MB, whichever is more */ arc_c_min = MAX(arc_c / 4, 64<<18); /* set max to 1/2 of all memory, or all but 1GB, whichever is more */ if (arc_c * 8 >= 1<<30) arc_c_max = (arc_c * 8) - (1<<30); else arc_c_max = arc_c_min; arc_c_max = MAX(arc_c * 5, arc_c_max); #ifdef _KERNEL /* * Allow the tunables to override our calculations if they are * reasonable (ie. over 16MB) */ if (zfs_arc_max > 64<<18 && zfs_arc_max < kmem_size()) arc_c_max = zfs_arc_max; if (zfs_arc_min > 64<<18 && zfs_arc_min <= arc_c_max) arc_c_min = zfs_arc_min; #endif arc_c = arc_c_max; arc_p = (arc_c >> 1); /* limit meta-data to 1/4 of the arc capacity */ arc_meta_limit = arc_c_max / 4; /* Allow the tunable to override if it is reasonable */ if (zfs_arc_meta_limit > 0 && zfs_arc_meta_limit <= arc_c_max) arc_meta_limit = zfs_arc_meta_limit; if (arc_c_min < arc_meta_limit / 2 && zfs_arc_min == 0) arc_c_min = arc_meta_limit / 2; if (zfs_arc_grow_retry > 0) arc_grow_retry = zfs_arc_grow_retry; if (zfs_arc_shrink_shift > 0) arc_shrink_shift = zfs_arc_shrink_shift; if (zfs_arc_p_min_shift > 0) arc_p_min_shift = zfs_arc_p_min_shift; /* if kmem_flags are set, lets try to use less memory */ if (kmem_debugging()) arc_c = arc_c / 2; if (arc_c < arc_c_min) arc_c = arc_c_min; zfs_arc_min = arc_c_min; zfs_arc_max = arc_c_max; arc_anon = &ARC_anon; arc_mru = &ARC_mru; arc_mru_ghost = &ARC_mru_ghost; arc_mfu = &ARC_mfu; arc_mfu_ghost = &ARC_mfu_ghost; arc_l2c_only = &ARC_l2c_only; arc_size = 0; for (i = 0; i < ARC_BUFC_NUMLISTS; i++) { mutex_init(&arc_anon->arcs_locks[i].arcs_lock, NULL, MUTEX_DEFAULT, NULL); mutex_init(&arc_mru->arcs_locks[i].arcs_lock, NULL, MUTEX_DEFAULT, NULL); mutex_init(&arc_mru_ghost->arcs_locks[i].arcs_lock, NULL, MUTEX_DEFAULT, NULL); mutex_init(&arc_mfu->arcs_locks[i].arcs_lock, NULL, MUTEX_DEFAULT, NULL); mutex_init(&arc_mfu_ghost->arcs_locks[i].arcs_lock, NULL, MUTEX_DEFAULT, NULL); mutex_init(&arc_l2c_only->arcs_locks[i].arcs_lock, NULL, MUTEX_DEFAULT, NULL); list_create(&arc_mru->arcs_lists[i], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node)); list_create(&arc_mru_ghost->arcs_lists[i], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node)); list_create(&arc_mfu->arcs_lists[i], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node)); list_create(&arc_mfu_ghost->arcs_lists[i], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node)); list_create(&arc_mfu_ghost->arcs_lists[i], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node)); list_create(&arc_l2c_only->arcs_lists[i], sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node)); } buf_init(); arc_thread_exit = 0; arc_eviction_list = NULL; mutex_init(&arc_eviction_mtx, NULL, MUTEX_DEFAULT, NULL); bzero(&arc_eviction_hdr, sizeof (arc_buf_hdr_t)); arc_ksp = kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED, sizeof (arc_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL); if (arc_ksp != NULL) { arc_ksp->ks_data = &arc_stats; kstat_install(arc_ksp); } (void) thread_create(NULL, 0, arc_reclaim_thread, NULL, 0, &p0, TS_RUN, minclsyspri); #ifdef _KERNEL arc_event_lowmem = EVENTHANDLER_REGISTER(vm_lowmem, arc_lowmem, NULL, EVENTHANDLER_PRI_FIRST); #endif arc_dead = FALSE; arc_warm = B_FALSE; /* * Calculate maximum amount of dirty data per pool. * * If it has been set by /etc/system, take that. * Otherwise, use a percentage of physical memory defined by * zfs_dirty_data_max_percent (default 10%) with a cap at * zfs_dirty_data_max_max (default 4GB). */ if (zfs_dirty_data_max == 0) { zfs_dirty_data_max = ptob(physmem) * zfs_dirty_data_max_percent / 100; zfs_dirty_data_max = MIN(zfs_dirty_data_max, zfs_dirty_data_max_max); } #ifdef _KERNEL if (TUNABLE_INT_FETCH("vfs.zfs.prefetch_disable", &zfs_prefetch_disable)) prefetch_tunable_set = 1; #ifdef __i386__ if (prefetch_tunable_set == 0) { printf("ZFS NOTICE: Prefetch is disabled by default on i386 " "-- to enable,\n"); printf(" add \"vfs.zfs.prefetch_disable=0\" " "to /boot/loader.conf.\n"); zfs_prefetch_disable = 1; } #else if ((((uint64_t)physmem * PAGESIZE) < (1ULL << 32)) && prefetch_tunable_set == 0) { printf("ZFS NOTICE: Prefetch is disabled by default if less " "than 4GB of RAM is present;\n" " to enable, add \"vfs.zfs.prefetch_disable=0\" " "to /boot/loader.conf.\n"); zfs_prefetch_disable = 1; } #endif /* Warn about ZFS memory and address space requirements. */ if (((uint64_t)physmem * PAGESIZE) < (256 + 128 + 64) * (1 << 20)) { printf("ZFS WARNING: Recommended minimum RAM size is 512MB; " "expect unstable behavior.\n"); } if (kmem_size() < 512 * (1 << 20)) { printf("ZFS WARNING: Recommended minimum kmem_size is 512MB; " "expect unstable behavior.\n"); printf(" Consider tuning vm.kmem_size and " "vm.kmem_size_max\n"); printf(" in /boot/loader.conf.\n"); } #endif } void arc_fini(void) { int i; mutex_enter(&arc_reclaim_thr_lock); arc_thread_exit = 1; cv_signal(&arc_reclaim_thr_cv); while (arc_thread_exit != 0) cv_wait(&arc_reclaim_thr_cv, &arc_reclaim_thr_lock); mutex_exit(&arc_reclaim_thr_lock); arc_flush(NULL); arc_dead = TRUE; if (arc_ksp != NULL) { kstat_delete(arc_ksp); arc_ksp = NULL; } mutex_destroy(&arc_eviction_mtx); mutex_destroy(&arc_reclaim_thr_lock); cv_destroy(&arc_reclaim_thr_cv); for (i = 0; i < ARC_BUFC_NUMLISTS; i++) { list_destroy(&arc_mru->arcs_lists[i]); list_destroy(&arc_mru_ghost->arcs_lists[i]); list_destroy(&arc_mfu->arcs_lists[i]); list_destroy(&arc_mfu_ghost->arcs_lists[i]); list_destroy(&arc_l2c_only->arcs_lists[i]); mutex_destroy(&arc_anon->arcs_locks[i].arcs_lock); mutex_destroy(&arc_mru->arcs_locks[i].arcs_lock); mutex_destroy(&arc_mru_ghost->arcs_locks[i].arcs_lock); mutex_destroy(&arc_mfu->arcs_locks[i].arcs_lock); mutex_destroy(&arc_mfu_ghost->arcs_locks[i].arcs_lock); mutex_destroy(&arc_l2c_only->arcs_locks[i].arcs_lock); } buf_fini(); ASSERT(arc_loaned_bytes == 0); mutex_destroy(&arc_lowmem_lock); #ifdef _KERNEL if (arc_event_lowmem != NULL) EVENTHANDLER_DEREGISTER(vm_lowmem, arc_event_lowmem); #endif } /* * Level 2 ARC * * The level 2 ARC (L2ARC) is a cache layer in-between main memory and disk. * It uses dedicated storage devices to hold cached data, which are populated * using large infrequent writes. The main role of this cache is to boost * the performance of random read workloads. The intended L2ARC devices * include short-stroked disks, solid state disks, and other media with * substantially faster read latency than disk. * * +-----------------------+ * | ARC | * +-----------------------+ * | ^ ^ * | | | * l2arc_feed_thread() arc_read() * | | | * | l2arc read | * V | | * +---------------+ | * | L2ARC | | * +---------------+ | * | ^ | * l2arc_write() | | * | | | * V | | * +-------+ +-------+ * | vdev | | vdev | * | cache | | cache | * +-------+ +-------+ * +=========+ .-----. * : L2ARC : |-_____-| * : devices : | Disks | * +=========+ `-_____-' * * Read requests are satisfied from the following sources, in order: * * 1) ARC * 2) vdev cache of L2ARC devices * 3) L2ARC devices * 4) vdev cache of disks * 5) disks * * Some L2ARC device types exhibit extremely slow write performance. * To accommodate for this there are some significant differences between * the L2ARC and traditional cache design: * * 1. There is no eviction path from the ARC to the L2ARC. Evictions from * the ARC behave as usual, freeing buffers and placing headers on ghost * lists. The ARC does not send buffers to the L2ARC during eviction as * this would add inflated write latencies for all ARC memory pressure. * * 2. The L2ARC attempts to cache data from the ARC before it is evicted. * It does this by periodically scanning buffers from the eviction-end of * the MFU and MRU ARC lists, copying them to the L2ARC devices if they are * not already there. It scans until a headroom of buffers is satisfied, * which itself is a buffer for ARC eviction. If a compressible buffer is * found during scanning and selected for writing to an L2ARC device, we * temporarily boost scanning headroom during the next scan cycle to make * sure we adapt to compression effects (which might significantly reduce * the data volume we write to L2ARC). The thread that does this is * l2arc_feed_thread(), illustrated below; example sizes are included to * provide a better sense of ratio than this diagram: * * head --> tail * +---------------------+----------+ * ARC_mfu |:::::#:::::::::::::::|o#o###o###|-->. # already on L2ARC * +---------------------+----------+ | o L2ARC eligible * ARC_mru |:#:::::::::::::::::::|#o#ooo####|-->| : ARC buffer * +---------------------+----------+ | * 15.9 Gbytes ^ 32 Mbytes | * headroom | * l2arc_feed_thread() * | * l2arc write hand <--[oooo]--' * | 8 Mbyte * | write max * V * +==============================+ * L2ARC dev |####|#|###|###| |####| ... | * +==============================+ * 32 Gbytes * * 3. If an ARC buffer is copied to the L2ARC but then hit instead of * evicted, then the L2ARC has cached a buffer much sooner than it probably * needed to, potentially wasting L2ARC device bandwidth and storage. It is * safe to say that this is an uncommon case, since buffers at the end of * the ARC lists have moved there due to inactivity. * * 4. If the ARC evicts faster than the L2ARC can maintain a headroom, * then the L2ARC simply misses copying some buffers. This serves as a * pressure valve to prevent heavy read workloads from both stalling the ARC * with waits and clogging the L2ARC with writes. This also helps prevent * the potential for the L2ARC to churn if it attempts to cache content too * quickly, such as during backups of the entire pool. * * 5. After system boot and before the ARC has filled main memory, there are * no evictions from the ARC and so the tails of the ARC_mfu and ARC_mru * lists can remain mostly static. Instead of searching from tail of these * lists as pictured, the l2arc_feed_thread() will search from the list heads * for eligible buffers, greatly increasing its chance of finding them. * * The L2ARC device write speed is also boosted during this time so that * the L2ARC warms up faster. Since there have been no ARC evictions yet, * there are no L2ARC reads, and no fear of degrading read performance * through increased writes. * * 6. Writes to the L2ARC devices are grouped and sent in-sequence, so that * the vdev queue can aggregate them into larger and fewer writes. Each * device is written to in a rotor fashion, sweeping writes through * available space then repeating. * * 7. The L2ARC does not store dirty content. It never needs to flush * write buffers back to disk based storage. * * 8. If an ARC buffer is written (and dirtied) which also exists in the * L2ARC, the now stale L2ARC buffer is immediately dropped. * * The performance of the L2ARC can be tweaked by a number of tunables, which * may be necessary for different workloads: * * l2arc_write_max max write bytes per interval * l2arc_write_boost extra write bytes during device warmup * l2arc_noprefetch skip caching prefetched buffers * l2arc_headroom number of max device writes to precache * l2arc_headroom_boost when we find compressed buffers during ARC * scanning, we multiply headroom by this * percentage factor for the next scan cycle, * since more compressed buffers are likely to * be present * l2arc_feed_secs seconds between L2ARC writing * * Tunables may be removed or added as future performance improvements are * integrated, and also may become zpool properties. * * There are three key functions that control how the L2ARC warms up: * * l2arc_write_eligible() check if a buffer is eligible to cache * l2arc_write_size() calculate how much to write * l2arc_write_interval() calculate sleep delay between writes * * These three functions determine what to write, how much, and how quickly * to send writes. */ static boolean_t l2arc_write_eligible(uint64_t spa_guid, arc_buf_hdr_t *ab) { /* * A buffer is *not* eligible for the L2ARC if it: * 1. belongs to a different spa. * 2. is already cached on the L2ARC. * 3. has an I/O in progress (it may be an incomplete read). * 4. is flagged not eligible (zfs property). */ if (ab->b_spa != spa_guid) { ARCSTAT_BUMP(arcstat_l2_write_spa_mismatch); return (B_FALSE); } if (ab->b_l2hdr != NULL) { ARCSTAT_BUMP(arcstat_l2_write_in_l2); return (B_FALSE); } if (HDR_IO_IN_PROGRESS(ab)) { ARCSTAT_BUMP(arcstat_l2_write_hdr_io_in_progress); return (B_FALSE); } if (!HDR_L2CACHE(ab)) { ARCSTAT_BUMP(arcstat_l2_write_not_cacheable); return (B_FALSE); } return (B_TRUE); } static uint64_t l2arc_write_size(void) { uint64_t size; /* * Make sure our globals have meaningful values in case the user * altered them. */ size = l2arc_write_max; if (size == 0) { cmn_err(CE_NOTE, "Bad value for l2arc_write_max, value must " "be greater than zero, resetting it to the default (%d)", L2ARC_WRITE_SIZE); size = l2arc_write_max = L2ARC_WRITE_SIZE; } if (arc_warm == B_FALSE) size += l2arc_write_boost; return (size); } static clock_t l2arc_write_interval(clock_t began, uint64_t wanted, uint64_t wrote) { clock_t interval, next, now; /* * If the ARC lists are busy, increase our write rate; if the * lists are stale, idle back. This is achieved by checking * how much we previously wrote - if it was more than half of * what we wanted, schedule the next write much sooner. */ if (l2arc_feed_again && wrote > (wanted / 2)) interval = (hz * l2arc_feed_min_ms) / 1000; else interval = hz * l2arc_feed_secs; now = ddi_get_lbolt(); next = MAX(now, MIN(now + interval, began + interval)); return (next); } static void l2arc_hdr_stat_add(void) { ARCSTAT_INCR(arcstat_l2_hdr_size, HDR_SIZE + L2HDR_SIZE); ARCSTAT_INCR(arcstat_hdr_size, -HDR_SIZE); } static void l2arc_hdr_stat_remove(void) { ARCSTAT_INCR(arcstat_l2_hdr_size, -(HDR_SIZE + L2HDR_SIZE)); ARCSTAT_INCR(arcstat_hdr_size, HDR_SIZE); } /* * Cycle through L2ARC devices. This is how L2ARC load balances. * If a device is returned, this also returns holding the spa config lock. */ static l2arc_dev_t * l2arc_dev_get_next(void) { l2arc_dev_t *first, *next = NULL; /* * Lock out the removal of spas (spa_namespace_lock), then removal * of cache devices (l2arc_dev_mtx). Once a device has been selected, * both locks will be dropped and a spa config lock held instead. */ mutex_enter(&spa_namespace_lock); mutex_enter(&l2arc_dev_mtx); /* if there are no vdevs, there is nothing to do */ if (l2arc_ndev == 0) goto out; first = NULL; next = l2arc_dev_last; do { /* loop around the list looking for a non-faulted vdev */ if (next == NULL) { next = list_head(l2arc_dev_list); } else { next = list_next(l2arc_dev_list, next); if (next == NULL) next = list_head(l2arc_dev_list); } /* if we have come back to the start, bail out */ if (first == NULL) first = next; else if (next == first) break; } while (vdev_is_dead(next->l2ad_vdev)); /* if we were unable to find any usable vdevs, return NULL */ if (vdev_is_dead(next->l2ad_vdev)) next = NULL; l2arc_dev_last = next; out: mutex_exit(&l2arc_dev_mtx); /* * Grab the config lock to prevent the 'next' device from being * removed while we are writing to it. */ if (next != NULL) spa_config_enter(next->l2ad_spa, SCL_L2ARC, next, RW_READER); mutex_exit(&spa_namespace_lock); return (next); } /* * Free buffers that were tagged for destruction. */ static void l2arc_do_free_on_write() { list_t *buflist; l2arc_data_free_t *df, *df_prev; mutex_enter(&l2arc_free_on_write_mtx); buflist = l2arc_free_on_write; for (df = list_tail(buflist); df; df = df_prev) { df_prev = list_prev(buflist, df); ASSERT(df->l2df_data != NULL); ASSERT(df->l2df_func != NULL); df->l2df_func(df->l2df_data, df->l2df_size); list_remove(buflist, df); kmem_free(df, sizeof (l2arc_data_free_t)); } mutex_exit(&l2arc_free_on_write_mtx); } /* * A write to a cache device has completed. Update all headers to allow * reads from these buffers to begin. */ static void l2arc_write_done(zio_t *zio) { l2arc_write_callback_t *cb; l2arc_dev_t *dev; list_t *buflist; arc_buf_hdr_t *head, *ab, *ab_prev; l2arc_buf_hdr_t *abl2; kmutex_t *hash_lock; int64_t bytes_dropped = 0; cb = zio->io_private; ASSERT(cb != NULL); dev = cb->l2wcb_dev; ASSERT(dev != NULL); head = cb->l2wcb_head; ASSERT(head != NULL); buflist = dev->l2ad_buflist; ASSERT(buflist != NULL); DTRACE_PROBE2(l2arc__iodone, zio_t *, zio, l2arc_write_callback_t *, cb); if (zio->io_error != 0) ARCSTAT_BUMP(arcstat_l2_writes_error); mutex_enter(&l2arc_buflist_mtx); /* * All writes completed, or an error was hit. */ for (ab = list_prev(buflist, head); ab; ab = ab_prev) { ab_prev = list_prev(buflist, ab); abl2 = ab->b_l2hdr; /* * Release the temporary compressed buffer as soon as possible. */ if (abl2->b_compress != ZIO_COMPRESS_OFF) l2arc_release_cdata_buf(ab); hash_lock = HDR_LOCK(ab); if (!mutex_tryenter(hash_lock)) { /* * This buffer misses out. It may be in a stage * of eviction. Its ARC_L2_WRITING flag will be * left set, denying reads to this buffer. */ ARCSTAT_BUMP(arcstat_l2_writes_hdr_miss); continue; } if (zio->io_error != 0) { /* * Error - drop L2ARC entry. */ list_remove(buflist, ab); ARCSTAT_INCR(arcstat_l2_asize, -abl2->b_asize); bytes_dropped += abl2->b_asize; ab->b_l2hdr = NULL; trim_map_free(abl2->b_dev->l2ad_vdev, abl2->b_daddr, ab->b_size, 0); kmem_free(abl2, sizeof (l2arc_buf_hdr_t)); ARCSTAT_INCR(arcstat_l2_size, -ab->b_size); } /* * Allow ARC to begin reads to this L2ARC entry. */ ab->b_flags &= ~ARC_L2_WRITING; mutex_exit(hash_lock); } atomic_inc_64(&l2arc_writes_done); list_remove(buflist, head); kmem_cache_free(hdr_cache, head); mutex_exit(&l2arc_buflist_mtx); vdev_space_update(dev->l2ad_vdev, -bytes_dropped, 0, 0); l2arc_do_free_on_write(); kmem_free(cb, sizeof (l2arc_write_callback_t)); } /* * A read to a cache device completed. Validate buffer contents before * handing over to the regular ARC routines. */ static void l2arc_read_done(zio_t *zio) { l2arc_read_callback_t *cb; arc_buf_hdr_t *hdr; arc_buf_t *buf; kmutex_t *hash_lock; int equal; ASSERT(zio->io_vd != NULL); ASSERT(zio->io_flags & ZIO_FLAG_DONT_PROPAGATE); spa_config_exit(zio->io_spa, SCL_L2ARC, zio->io_vd); cb = zio->io_private; ASSERT(cb != NULL); buf = cb->l2rcb_buf; ASSERT(buf != NULL); hash_lock = HDR_LOCK(buf->b_hdr); mutex_enter(hash_lock); hdr = buf->b_hdr; ASSERT3P(hash_lock, ==, HDR_LOCK(hdr)); /* * If the buffer was compressed, decompress it first. */ if (cb->l2rcb_compress != ZIO_COMPRESS_OFF) l2arc_decompress_zio(zio, hdr, cb->l2rcb_compress); ASSERT(zio->io_data != NULL); /* * Check this survived the L2ARC journey. */ equal = arc_cksum_equal(buf); if (equal && zio->io_error == 0 && !HDR_L2_EVICTED(hdr)) { mutex_exit(hash_lock); zio->io_private = buf; zio->io_bp_copy = cb->l2rcb_bp; /* XXX fix in L2ARC 2.0 */ zio->io_bp = &zio->io_bp_copy; /* XXX fix in L2ARC 2.0 */ arc_read_done(zio); } else { mutex_exit(hash_lock); /* * Buffer didn't survive caching. Increment stats and * reissue to the original storage device. */ if (zio->io_error != 0) { ARCSTAT_BUMP(arcstat_l2_io_error); } else { zio->io_error = SET_ERROR(EIO); } if (!equal) ARCSTAT_BUMP(arcstat_l2_cksum_bad); /* * If there's no waiter, issue an async i/o to the primary * storage now. If there *is* a waiter, the caller must * issue the i/o in a context where it's OK to block. */ if (zio->io_waiter == NULL) { zio_t *pio = zio_unique_parent(zio); ASSERT(!pio || pio->io_child_type == ZIO_CHILD_LOGICAL); zio_nowait(zio_read(pio, cb->l2rcb_spa, &cb->l2rcb_bp, buf->b_data, zio->io_size, arc_read_done, buf, zio->io_priority, cb->l2rcb_flags, &cb->l2rcb_zb)); } } kmem_free(cb, sizeof (l2arc_read_callback_t)); } /* * This is the list priority from which the L2ARC will search for pages to * cache. This is used within loops (0..3) to cycle through lists in the * desired order. This order can have a significant effect on cache * performance. * * Currently the metadata lists are hit first, MFU then MRU, followed by * the data lists. This function returns a locked list, and also returns * the lock pointer. */ static list_t * l2arc_list_locked(int list_num, kmutex_t **lock) { list_t *list = NULL; int idx; ASSERT(list_num >= 0 && list_num < 2 * ARC_BUFC_NUMLISTS); if (list_num < ARC_BUFC_NUMMETADATALISTS) { idx = list_num; list = &arc_mfu->arcs_lists[idx]; *lock = ARCS_LOCK(arc_mfu, idx); } else if (list_num < ARC_BUFC_NUMMETADATALISTS * 2) { idx = list_num - ARC_BUFC_NUMMETADATALISTS; list = &arc_mru->arcs_lists[idx]; *lock = ARCS_LOCK(arc_mru, idx); } else if (list_num < (ARC_BUFC_NUMMETADATALISTS * 2 + ARC_BUFC_NUMDATALISTS)) { idx = list_num - ARC_BUFC_NUMMETADATALISTS; list = &arc_mfu->arcs_lists[idx]; *lock = ARCS_LOCK(arc_mfu, idx); } else { idx = list_num - ARC_BUFC_NUMLISTS; list = &arc_mru->arcs_lists[idx]; *lock = ARCS_LOCK(arc_mru, idx); } ASSERT(!(MUTEX_HELD(*lock))); mutex_enter(*lock); return (list); } /* * Evict buffers from the device write hand to the distance specified in * bytes. This distance may span populated buffers, it may span nothing. * This is clearing a region on the L2ARC device ready for writing. * If the 'all' boolean is set, every buffer is evicted. */ static void l2arc_evict(l2arc_dev_t *dev, uint64_t distance, boolean_t all) { list_t *buflist; l2arc_buf_hdr_t *abl2; arc_buf_hdr_t *ab, *ab_prev; kmutex_t *hash_lock; uint64_t taddr; int64_t bytes_evicted = 0; buflist = dev->l2ad_buflist; if (buflist == NULL) return; if (!all && dev->l2ad_first) { /* * This is the first sweep through the device. There is * nothing to evict. */ return; } if (dev->l2ad_hand >= (dev->l2ad_end - (2 * distance))) { /* * When nearing the end of the device, evict to the end * before the device write hand jumps to the start. */ taddr = dev->l2ad_end; } else { taddr = dev->l2ad_hand + distance; } DTRACE_PROBE4(l2arc__evict, l2arc_dev_t *, dev, list_t *, buflist, uint64_t, taddr, boolean_t, all); top: mutex_enter(&l2arc_buflist_mtx); for (ab = list_tail(buflist); ab; ab = ab_prev) { ab_prev = list_prev(buflist, ab); hash_lock = HDR_LOCK(ab); if (!mutex_tryenter(hash_lock)) { /* * Missed the hash lock. Retry. */ ARCSTAT_BUMP(arcstat_l2_evict_lock_retry); mutex_exit(&l2arc_buflist_mtx); mutex_enter(hash_lock); mutex_exit(hash_lock); goto top; } if (HDR_L2_WRITE_HEAD(ab)) { /* * We hit a write head node. Leave it for * l2arc_write_done(). */ list_remove(buflist, ab); mutex_exit(hash_lock); continue; } if (!all && ab->b_l2hdr != NULL && (ab->b_l2hdr->b_daddr > taddr || ab->b_l2hdr->b_daddr < dev->l2ad_hand)) { /* * We've evicted to the target address, * or the end of the device. */ mutex_exit(hash_lock); break; } if (HDR_FREE_IN_PROGRESS(ab)) { /* * Already on the path to destruction. */ mutex_exit(hash_lock); continue; } if (ab->b_state == arc_l2c_only) { ASSERT(!HDR_L2_READING(ab)); /* * This doesn't exist in the ARC. Destroy. * arc_hdr_destroy() will call list_remove() * and decrement arcstat_l2_size. */ arc_change_state(arc_anon, ab, hash_lock); arc_hdr_destroy(ab); } else { /* * Invalidate issued or about to be issued * reads, since we may be about to write * over this location. */ if (HDR_L2_READING(ab)) { ARCSTAT_BUMP(arcstat_l2_evict_reading); ab->b_flags |= ARC_L2_EVICTED; } /* * Tell ARC this no longer exists in L2ARC. */ if (ab->b_l2hdr != NULL) { abl2 = ab->b_l2hdr; ARCSTAT_INCR(arcstat_l2_asize, -abl2->b_asize); bytes_evicted += abl2->b_asize; ab->b_l2hdr = NULL; kmem_free(abl2, sizeof (l2arc_buf_hdr_t)); ARCSTAT_INCR(arcstat_l2_size, -ab->b_size); } list_remove(buflist, ab); /* * This may have been leftover after a * failed write. */ ab->b_flags &= ~ARC_L2_WRITING; } mutex_exit(hash_lock); } mutex_exit(&l2arc_buflist_mtx); vdev_space_update(dev->l2ad_vdev, -bytes_evicted, 0, 0); dev->l2ad_evict = taddr; } /* * Find and write ARC buffers to the L2ARC device. * * An ARC_L2_WRITING flag is set so that the L2ARC buffers are not valid * for reading until they have completed writing. * The headroom_boost is an in-out parameter used to maintain headroom boost * state between calls to this function. * * Returns the number of bytes actually written (which may be smaller than * the delta by which the device hand has changed due to alignment). */ static uint64_t l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, boolean_t *headroom_boost) { arc_buf_hdr_t *ab, *ab_prev, *head; list_t *list; uint64_t write_asize, write_psize, write_sz, headroom, buf_compress_minsz; void *buf_data; kmutex_t *list_lock; boolean_t full; l2arc_write_callback_t *cb; zio_t *pio, *wzio; uint64_t guid = spa_load_guid(spa); const boolean_t do_headroom_boost = *headroom_boost; int try; ASSERT(dev->l2ad_vdev != NULL); /* Lower the flag now, we might want to raise it again later. */ *headroom_boost = B_FALSE; pio = NULL; write_sz = write_asize = write_psize = 0; full = B_FALSE; head = kmem_cache_alloc(hdr_cache, KM_PUSHPAGE); head->b_flags |= ARC_L2_WRITE_HEAD; ARCSTAT_BUMP(arcstat_l2_write_buffer_iter); /* * We will want to try to compress buffers that are at least 2x the * device sector size. */ buf_compress_minsz = 2 << dev->l2ad_vdev->vdev_ashift; /* * Copy buffers for L2ARC writing. */ mutex_enter(&l2arc_buflist_mtx); for (try = 0; try < 2 * ARC_BUFC_NUMLISTS; try++) { uint64_t passed_sz = 0; list = l2arc_list_locked(try, &list_lock); ARCSTAT_BUMP(arcstat_l2_write_buffer_list_iter); /* * L2ARC fast warmup. * * Until the ARC is warm and starts to evict, read from the * head of the ARC lists rather than the tail. */ if (arc_warm == B_FALSE) ab = list_head(list); else ab = list_tail(list); if (ab == NULL) ARCSTAT_BUMP(arcstat_l2_write_buffer_list_null_iter); headroom = target_sz * l2arc_headroom; if (do_headroom_boost) headroom = (headroom * l2arc_headroom_boost) / 100; for (; ab; ab = ab_prev) { l2arc_buf_hdr_t *l2hdr; kmutex_t *hash_lock; uint64_t buf_sz; if (arc_warm == B_FALSE) ab_prev = list_next(list, ab); else ab_prev = list_prev(list, ab); ARCSTAT_INCR(arcstat_l2_write_buffer_bytes_scanned, ab->b_size); hash_lock = HDR_LOCK(ab); if (!mutex_tryenter(hash_lock)) { ARCSTAT_BUMP(arcstat_l2_write_trylock_fail); /* * Skip this buffer rather than waiting. */ continue; } passed_sz += ab->b_size; if (passed_sz > headroom) { /* * Searched too far. */ mutex_exit(hash_lock); ARCSTAT_BUMP(arcstat_l2_write_passed_headroom); break; } if (!l2arc_write_eligible(guid, ab)) { mutex_exit(hash_lock); continue; } if ((write_sz + ab->b_size) > target_sz) { full = B_TRUE; mutex_exit(hash_lock); ARCSTAT_BUMP(arcstat_l2_write_full); break; } if (pio == NULL) { /* * Insert a dummy header on the buflist so * l2arc_write_done() can find where the * write buffers begin without searching. */ list_insert_head(dev->l2ad_buflist, head); cb = kmem_alloc( sizeof (l2arc_write_callback_t), KM_SLEEP); cb->l2wcb_dev = dev; cb->l2wcb_head = head; pio = zio_root(spa, l2arc_write_done, cb, ZIO_FLAG_CANFAIL); ARCSTAT_BUMP(arcstat_l2_write_pios); } /* * Create and add a new L2ARC header. */ l2hdr = kmem_zalloc(sizeof (l2arc_buf_hdr_t), KM_SLEEP); l2hdr->b_dev = dev; ab->b_flags |= ARC_L2_WRITING; /* * Temporarily stash the data buffer in b_tmp_cdata. * The subsequent write step will pick it up from * there. This is because can't access ab->b_buf * without holding the hash_lock, which we in turn * can't access without holding the ARC list locks * (which we want to avoid during compression/writing). */ l2hdr->b_compress = ZIO_COMPRESS_OFF; l2hdr->b_asize = ab->b_size; l2hdr->b_tmp_cdata = ab->b_buf->b_data; buf_sz = ab->b_size; ab->b_l2hdr = l2hdr; list_insert_head(dev->l2ad_buflist, ab); /* * Compute and store the buffer cksum before * writing. On debug the cksum is verified first. */ arc_cksum_verify(ab->b_buf); arc_cksum_compute(ab->b_buf, B_TRUE); mutex_exit(hash_lock); write_sz += buf_sz; } mutex_exit(list_lock); if (full == B_TRUE) break; } /* No buffers selected for writing? */ if (pio == NULL) { ASSERT0(write_sz); mutex_exit(&l2arc_buflist_mtx); kmem_cache_free(hdr_cache, head); return (0); } /* * Now start writing the buffers. We're starting at the write head * and work backwards, retracing the course of the buffer selector * loop above. */ for (ab = list_prev(dev->l2ad_buflist, head); ab; ab = list_prev(dev->l2ad_buflist, ab)) { l2arc_buf_hdr_t *l2hdr; uint64_t buf_sz; /* * We shouldn't need to lock the buffer here, since we flagged * it as ARC_L2_WRITING in the previous step, but we must take * care to only access its L2 cache parameters. In particular, * ab->b_buf may be invalid by now due to ARC eviction. */ l2hdr = ab->b_l2hdr; l2hdr->b_daddr = dev->l2ad_hand; if ((ab->b_flags & ARC_L2COMPRESS) && l2hdr->b_asize >= buf_compress_minsz) { if (l2arc_compress_buf(l2hdr)) { /* * If compression succeeded, enable headroom * boost on the next scan cycle. */ *headroom_boost = B_TRUE; } } /* * Pick up the buffer data we had previously stashed away * (and now potentially also compressed). */ buf_data = l2hdr->b_tmp_cdata; buf_sz = l2hdr->b_asize; /* Compression may have squashed the buffer to zero length. */ if (buf_sz != 0) { uint64_t buf_p_sz; wzio = zio_write_phys(pio, dev->l2ad_vdev, dev->l2ad_hand, buf_sz, buf_data, ZIO_CHECKSUM_OFF, NULL, NULL, ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_CANFAIL, B_FALSE); DTRACE_PROBE2(l2arc__write, vdev_t *, dev->l2ad_vdev, zio_t *, wzio); (void) zio_nowait(wzio); write_asize += buf_sz; /* * Keep the clock hand suitably device-aligned. */ buf_p_sz = vdev_psize_to_asize(dev->l2ad_vdev, buf_sz); write_psize += buf_p_sz; dev->l2ad_hand += buf_p_sz; } } mutex_exit(&l2arc_buflist_mtx); ASSERT3U(write_asize, <=, target_sz); ARCSTAT_BUMP(arcstat_l2_writes_sent); ARCSTAT_INCR(arcstat_l2_write_bytes, write_asize); ARCSTAT_INCR(arcstat_l2_size, write_sz); ARCSTAT_INCR(arcstat_l2_asize, write_asize); vdev_space_update(dev->l2ad_vdev, write_asize, 0, 0); /* * Bump device hand to the device start if it is approaching the end. * l2arc_evict() will already have evicted ahead for this case. */ if (dev->l2ad_hand >= (dev->l2ad_end - target_sz)) { dev->l2ad_hand = dev->l2ad_start; dev->l2ad_evict = dev->l2ad_start; dev->l2ad_first = B_FALSE; } dev->l2ad_writing = B_TRUE; (void) zio_wait(pio); dev->l2ad_writing = B_FALSE; return (write_asize); } /* * Compresses an L2ARC buffer. * The data to be compressed must be prefilled in l2hdr->b_tmp_cdata and its * size in l2hdr->b_asize. This routine tries to compress the data and * depending on the compression result there are three possible outcomes: * *) The buffer was incompressible. The original l2hdr contents were left * untouched and are ready for writing to an L2 device. * *) The buffer was all-zeros, so there is no need to write it to an L2 * device. To indicate this situation b_tmp_cdata is NULL'ed, b_asize is * set to zero and b_compress is set to ZIO_COMPRESS_EMPTY. * *) Compression succeeded and b_tmp_cdata was replaced with a temporary * data buffer which holds the compressed data to be written, and b_asize * tells us how much data there is. b_compress is set to the appropriate * compression algorithm. Once writing is done, invoke * l2arc_release_cdata_buf on this l2hdr to free this temporary buffer. * * Returns B_TRUE if compression succeeded, or B_FALSE if it didn't (the * buffer was incompressible). */ static boolean_t l2arc_compress_buf(l2arc_buf_hdr_t *l2hdr) { void *cdata; size_t csize, len, rounded; ASSERT(l2hdr->b_compress == ZIO_COMPRESS_OFF); ASSERT(l2hdr->b_tmp_cdata != NULL); len = l2hdr->b_asize; cdata = zio_data_buf_alloc(len); csize = zio_compress_data(ZIO_COMPRESS_LZ4, l2hdr->b_tmp_cdata, cdata, l2hdr->b_asize); rounded = P2ROUNDUP(csize, (size_t)SPA_MINBLOCKSIZE); if (rounded > csize) { bzero((char *)cdata + csize, rounded - csize); csize = rounded; } if (csize == 0) { /* zero block, indicate that there's nothing to write */ zio_data_buf_free(cdata, len); l2hdr->b_compress = ZIO_COMPRESS_EMPTY; l2hdr->b_asize = 0; l2hdr->b_tmp_cdata = NULL; ARCSTAT_BUMP(arcstat_l2_compress_zeros); return (B_TRUE); } else if (csize > 0 && csize < len) { /* * Compression succeeded, we'll keep the cdata around for * writing and release it afterwards. */ l2hdr->b_compress = ZIO_COMPRESS_LZ4; l2hdr->b_asize = csize; l2hdr->b_tmp_cdata = cdata; ARCSTAT_BUMP(arcstat_l2_compress_successes); return (B_TRUE); } else { /* * Compression failed, release the compressed buffer. * l2hdr will be left unmodified. */ zio_data_buf_free(cdata, len); ARCSTAT_BUMP(arcstat_l2_compress_failures); return (B_FALSE); } } /* * Decompresses a zio read back from an l2arc device. On success, the * underlying zio's io_data buffer is overwritten by the uncompressed * version. On decompression error (corrupt compressed stream), the * zio->io_error value is set to signal an I/O error. * * Please note that the compressed data stream is not checksummed, so * if the underlying device is experiencing data corruption, we may feed * corrupt data to the decompressor, so the decompressor needs to be * able to handle this situation (LZ4 does). */ static void l2arc_decompress_zio(zio_t *zio, arc_buf_hdr_t *hdr, enum zio_compress c) { ASSERT(L2ARC_IS_VALID_COMPRESS(c)); if (zio->io_error != 0) { /* * An io error has occured, just restore the original io * size in preparation for a main pool read. */ zio->io_orig_size = zio->io_size = hdr->b_size; return; } if (c == ZIO_COMPRESS_EMPTY) { /* * An empty buffer results in a null zio, which means we * need to fill its io_data after we're done restoring the * buffer's contents. */ ASSERT(hdr->b_buf != NULL); bzero(hdr->b_buf->b_data, hdr->b_size); zio->io_data = zio->io_orig_data = hdr->b_buf->b_data; } else { ASSERT(zio->io_data != NULL); /* * We copy the compressed data from the start of the arc buffer * (the zio_read will have pulled in only what we need, the * rest is garbage which we will overwrite at decompression) * and then decompress back to the ARC data buffer. This way we * can minimize copying by simply decompressing back over the * original compressed data (rather than decompressing to an * aux buffer and then copying back the uncompressed buffer, * which is likely to be much larger). */ uint64_t csize; void *cdata; csize = zio->io_size; cdata = zio_data_buf_alloc(csize); bcopy(zio->io_data, cdata, csize); if (zio_decompress_data(c, cdata, zio->io_data, csize, hdr->b_size) != 0) zio->io_error = EIO; zio_data_buf_free(cdata, csize); } /* Restore the expected uncompressed IO size. */ zio->io_orig_size = zio->io_size = hdr->b_size; } /* * Releases the temporary b_tmp_cdata buffer in an l2arc header structure. * This buffer serves as a temporary holder of compressed data while * the buffer entry is being written to an l2arc device. Once that is * done, we can dispose of it. */ static void l2arc_release_cdata_buf(arc_buf_hdr_t *ab) { l2arc_buf_hdr_t *l2hdr = ab->b_l2hdr; if (l2hdr->b_compress == ZIO_COMPRESS_LZ4) { /* * If the data was compressed, then we've allocated a * temporary buffer for it, so now we need to release it. */ ASSERT(l2hdr->b_tmp_cdata != NULL); zio_data_buf_free(l2hdr->b_tmp_cdata, ab->b_size); } l2hdr->b_tmp_cdata = NULL; } /* * This thread feeds the L2ARC at regular intervals. This is the beating * heart of the L2ARC. */ static void l2arc_feed_thread(void *dummy __unused) { callb_cpr_t cpr; l2arc_dev_t *dev; spa_t *spa; uint64_t size, wrote; clock_t begin, next = ddi_get_lbolt(); boolean_t headroom_boost = B_FALSE; CALLB_CPR_INIT(&cpr, &l2arc_feed_thr_lock, callb_generic_cpr, FTAG); mutex_enter(&l2arc_feed_thr_lock); while (l2arc_thread_exit == 0) { CALLB_CPR_SAFE_BEGIN(&cpr); (void) cv_timedwait(&l2arc_feed_thr_cv, &l2arc_feed_thr_lock, next - ddi_get_lbolt()); CALLB_CPR_SAFE_END(&cpr, &l2arc_feed_thr_lock); next = ddi_get_lbolt() + hz; /* * Quick check for L2ARC devices. */ mutex_enter(&l2arc_dev_mtx); if (l2arc_ndev == 0) { mutex_exit(&l2arc_dev_mtx); continue; } mutex_exit(&l2arc_dev_mtx); begin = ddi_get_lbolt(); /* * This selects the next l2arc device to write to, and in * doing so the next spa to feed from: dev->l2ad_spa. This * will return NULL if there are now no l2arc devices or if * they are all faulted. * * If a device is returned, its spa's config lock is also * held to prevent device removal. l2arc_dev_get_next() * will grab and release l2arc_dev_mtx. */ if ((dev = l2arc_dev_get_next()) == NULL) continue; spa = dev->l2ad_spa; ASSERT(spa != NULL); /* * If the pool is read-only then force the feed thread to * sleep a little longer. */ if (!spa_writeable(spa)) { next = ddi_get_lbolt() + 5 * l2arc_feed_secs * hz; spa_config_exit(spa, SCL_L2ARC, dev); continue; } /* * Avoid contributing to memory pressure. */ if (arc_reclaim_needed()) { ARCSTAT_BUMP(arcstat_l2_abort_lowmem); spa_config_exit(spa, SCL_L2ARC, dev); continue; } ARCSTAT_BUMP(arcstat_l2_feeds); size = l2arc_write_size(); /* * Evict L2ARC buffers that will be overwritten. */ l2arc_evict(dev, size, B_FALSE); /* * Write ARC buffers. */ wrote = l2arc_write_buffers(spa, dev, size, &headroom_boost); /* * Calculate interval between writes. */ next = l2arc_write_interval(begin, size, wrote); spa_config_exit(spa, SCL_L2ARC, dev); } l2arc_thread_exit = 0; cv_broadcast(&l2arc_feed_thr_cv); CALLB_CPR_EXIT(&cpr); /* drops l2arc_feed_thr_lock */ thread_exit(); } boolean_t l2arc_vdev_present(vdev_t *vd) { l2arc_dev_t *dev; mutex_enter(&l2arc_dev_mtx); for (dev = list_head(l2arc_dev_list); dev != NULL; dev = list_next(l2arc_dev_list, dev)) { if (dev->l2ad_vdev == vd) break; } mutex_exit(&l2arc_dev_mtx); return (dev != NULL); } /* * Add a vdev for use by the L2ARC. By this point the spa has already * validated the vdev and opened it. */ void l2arc_add_vdev(spa_t *spa, vdev_t *vd) { l2arc_dev_t *adddev; ASSERT(!l2arc_vdev_present(vd)); vdev_ashift_optimize(vd); /* * Create a new l2arc device entry. */ adddev = kmem_zalloc(sizeof (l2arc_dev_t), KM_SLEEP); adddev->l2ad_spa = spa; adddev->l2ad_vdev = vd; adddev->l2ad_start = VDEV_LABEL_START_SIZE; adddev->l2ad_end = VDEV_LABEL_START_SIZE + vdev_get_min_asize(vd); adddev->l2ad_hand = adddev->l2ad_start; adddev->l2ad_evict = adddev->l2ad_start; adddev->l2ad_first = B_TRUE; adddev->l2ad_writing = B_FALSE; /* * This is a list of all ARC buffers that are still valid on the * device. */ adddev->l2ad_buflist = kmem_zalloc(sizeof (list_t), KM_SLEEP); list_create(adddev->l2ad_buflist, sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_l2node)); vdev_space_update(vd, 0, 0, adddev->l2ad_end - adddev->l2ad_hand); /* * Add device to global list */ mutex_enter(&l2arc_dev_mtx); list_insert_head(l2arc_dev_list, adddev); atomic_inc_64(&l2arc_ndev); mutex_exit(&l2arc_dev_mtx); } /* * Remove a vdev from the L2ARC. */ void l2arc_remove_vdev(vdev_t *vd) { l2arc_dev_t *dev, *nextdev, *remdev = NULL; /* * Find the device by vdev */ mutex_enter(&l2arc_dev_mtx); for (dev = list_head(l2arc_dev_list); dev; dev = nextdev) { nextdev = list_next(l2arc_dev_list, dev); if (vd == dev->l2ad_vdev) { remdev = dev; break; } } ASSERT(remdev != NULL); /* * Remove device from global list */ list_remove(l2arc_dev_list, remdev); l2arc_dev_last = NULL; /* may have been invalidated */ atomic_dec_64(&l2arc_ndev); mutex_exit(&l2arc_dev_mtx); /* * Clear all buflists and ARC references. L2ARC device flush. */ l2arc_evict(remdev, 0, B_TRUE); list_destroy(remdev->l2ad_buflist); kmem_free(remdev->l2ad_buflist, sizeof (list_t)); kmem_free(remdev, sizeof (l2arc_dev_t)); } void l2arc_init(void) { l2arc_thread_exit = 0; l2arc_ndev = 0; l2arc_writes_sent = 0; l2arc_writes_done = 0; mutex_init(&l2arc_feed_thr_lock, NULL, MUTEX_DEFAULT, NULL); cv_init(&l2arc_feed_thr_cv, NULL, CV_DEFAULT, NULL); mutex_init(&l2arc_dev_mtx, NULL, MUTEX_DEFAULT, NULL); mutex_init(&l2arc_buflist_mtx, NULL, MUTEX_DEFAULT, NULL); mutex_init(&l2arc_free_on_write_mtx, NULL, MUTEX_DEFAULT, NULL); l2arc_dev_list = &L2ARC_dev_list; l2arc_free_on_write = &L2ARC_free_on_write; list_create(l2arc_dev_list, sizeof (l2arc_dev_t), offsetof(l2arc_dev_t, l2ad_node)); list_create(l2arc_free_on_write, sizeof (l2arc_data_free_t), offsetof(l2arc_data_free_t, l2df_list_node)); } void l2arc_fini(void) { /* * This is called from dmu_fini(), which is called from spa_fini(); * Because of this, we can assume that all l2arc devices have * already been removed when the pools themselves were removed. */ l2arc_do_free_on_write(); mutex_destroy(&l2arc_feed_thr_lock); cv_destroy(&l2arc_feed_thr_cv); mutex_destroy(&l2arc_dev_mtx); mutex_destroy(&l2arc_buflist_mtx); mutex_destroy(&l2arc_free_on_write_mtx); list_destroy(l2arc_dev_list); list_destroy(l2arc_free_on_write); } void l2arc_start(void) { if (!(spa_mode_global & FWRITE)) return; (void) thread_create(NULL, 0, l2arc_feed_thread, NULL, 0, &p0, TS_RUN, minclsyspri); } void l2arc_stop(void) { if (!(spa_mode_global & FWRITE)) return; mutex_enter(&l2arc_feed_thr_lock); cv_signal(&l2arc_feed_thr_cv); /* kick thread out of startup */ l2arc_thread_exit = 1; while (l2arc_thread_exit != 0) cv_wait(&l2arc_feed_thr_cv, &l2arc_feed_thr_lock); mutex_exit(&l2arc_feed_thr_lock); } Index: stable/10/sys/vm/vm_pageout.c =================================================================== --- stable/10/sys/vm/vm_pageout.c (revision 272874) +++ stable/10/sys/vm/vm_pageout.c (revision 272875) @@ -1,1882 +1,1901 @@ /*- * Copyright (c) 1991 Regents of the University of California. * All rights reserved. * Copyright (c) 1994 John S. Dyson * All rights reserved. * Copyright (c) 1994 David Greenman * All rights reserved. * Copyright (c) 2005 Yahoo! Technologies Norway AS * All rights reserved. * * This code is derived from software contributed to Berkeley by * The Mach Operating System project at Carnegie-Mellon University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 * * * Copyright (c) 1987, 1990 Carnegie-Mellon University. * All rights reserved. * * Authors: Avadis Tevanian, Jr., Michael Wayne Young * * Permission to use, copy, modify and distribute this software and * its documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. */ /* * The proverbial page-out daemon. */ #include __FBSDID("$FreeBSD$"); #include "opt_vm.h" +#include "opt_kdtrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include +#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * System initialization */ /* the kernel process "vm_pageout"*/ static void vm_pageout(void); +static void vm_pageout_init(void); static int vm_pageout_clean(vm_page_t); static void vm_pageout_scan(struct vm_domain *vmd, int pass); static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass); +SYSINIT(pagedaemon_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, vm_pageout_init, + NULL); + struct proc *pageproc; static struct kproc_desc page_kp = { "pagedaemon", vm_pageout, &pageproc }; -SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, +SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_SECOND, kproc_start, &page_kp); +SDT_PROVIDER_DEFINE(vm); +SDT_PROBE_DEFINE(vm, , , vm__lowmem_cache); +SDT_PROBE_DEFINE(vm, , , vm__lowmem_scan); + #if !defined(NO_SWAPPING) /* the kernel process "vm_daemon"*/ static void vm_daemon(void); static struct proc *vmproc; static struct kproc_desc vm_kp = { "vmdaemon", vm_daemon, &vmproc }; SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp); #endif int vm_pages_needed; /* Event on which pageout daemon sleeps */ int vm_pageout_deficit; /* Estimated number of pages deficit */ int vm_pageout_pages_needed; /* flag saying that the pageout daemon needs pages */ int vm_pageout_wakeup_thresh; #if !defined(NO_SWAPPING) static int vm_pageout_req_swapout; /* XXX */ static int vm_daemon_needed; static struct mtx vm_daemon_mtx; /* Allow for use by vm_pageout before vm_daemon is initialized. */ MTX_SYSINIT(vm_daemon, &vm_daemon_mtx, "vm daemon", MTX_DEF); #endif static int vm_max_launder = 32; static int vm_pageout_update_period; static int defer_swap_pageouts; static int disable_swap_pageouts; static int lowmem_period = 10; static int lowmem_ticks; #if defined(NO_SWAPPING) static int vm_swap_enabled = 0; static int vm_swap_idle_enabled = 0; #else static int vm_swap_enabled = 1; static int vm_swap_idle_enabled = 0; #endif SYSCTL_INT(_vm, OID_AUTO, pageout_wakeup_thresh, CTLFLAG_RW, &vm_pageout_wakeup_thresh, 0, "free page threshold for waking up the pageout daemon"); SYSCTL_INT(_vm, OID_AUTO, max_launder, CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); SYSCTL_INT(_vm, OID_AUTO, pageout_update_period, CTLFLAG_RW, &vm_pageout_update_period, 0, "Maximum active LRU update period"); SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RW, &lowmem_period, 0, "Low memory callback period"); #if defined(NO_SWAPPING) SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RD, &vm_swap_enabled, 0, "Enable entire process swapout"); SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RD, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); #else SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); #endif SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); static int pageout_lock_miss; SYSCTL_INT(_vm, OID_AUTO, pageout_lock_miss, CTLFLAG_RD, &pageout_lock_miss, 0, "vget() lock misses during pageout"); #define VM_PAGEOUT_PAGE_COUNT 16 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; int vm_page_max_wired; /* XXX max # of wired pages system-wide */ SYSCTL_INT(_vm, OID_AUTO, max_wired, CTLFLAG_RW, &vm_page_max_wired, 0, "System-wide limit to wired page count"); static boolean_t vm_pageout_fallback_object_lock(vm_page_t, vm_page_t *); static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int, vm_paddr_t, vm_paddr_t); #if !defined(NO_SWAPPING) static void vm_pageout_map_deactivate_pages(vm_map_t, long); static void vm_pageout_object_deactivate_pages(pmap_t, vm_object_t, long); static void vm_req_vmdaemon(int req); #endif static boolean_t vm_pageout_page_lock(vm_page_t, vm_page_t *); /* * Initialize a dummy page for marking the caller's place in the specified * paging queue. In principle, this function only needs to set the flag * PG_MARKER. Nonetheless, it wirte busies and initializes the hold count * to one as safety precautions. */ static void vm_pageout_init_marker(vm_page_t marker, u_short queue) { bzero(marker, sizeof(*marker)); marker->flags = PG_MARKER; marker->busy_lock = VPB_SINGLE_EXCLUSIVER; marker->queue = queue; marker->hold_count = 1; } /* * vm_pageout_fallback_object_lock: * * Lock vm object currently associated with `m'. VM_OBJECT_TRYWLOCK is * known to have failed and page queue must be either PQ_ACTIVE or * PQ_INACTIVE. To avoid lock order violation, unlock the page queues * while locking the vm object. Use marker page to detect page queue * changes and maintain notion of next page on page queue. Return * TRUE if no changes were detected, FALSE otherwise. vm object is * locked on return. * * This function depends on both the lock portion of struct vm_object * and normal struct vm_page being type stable. */ static boolean_t vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) { struct vm_page marker; struct vm_pagequeue *pq; boolean_t unchanged; u_short queue; vm_object_t object; queue = m->queue; vm_pageout_init_marker(&marker, queue); pq = vm_page_pagequeue(m); object = m->object; TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q); vm_pagequeue_unlock(pq); vm_page_unlock(m); VM_OBJECT_WLOCK(object); vm_page_lock(m); vm_pagequeue_lock(pq); /* Page queue might have changed. */ *next = TAILQ_NEXT(&marker, plinks.q); unchanged = (m->queue == queue && m->object == object && &marker == TAILQ_NEXT(m, plinks.q)); TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); return (unchanged); } /* * Lock the page while holding the page queue lock. Use marker page * to detect page queue changes and maintain notion of next page on * page queue. Return TRUE if no changes were detected, FALSE * otherwise. The page is locked on return. The page queue lock might * be dropped and reacquired. * * This function depends on normal struct vm_page being type stable. */ static boolean_t vm_pageout_page_lock(vm_page_t m, vm_page_t *next) { struct vm_page marker; struct vm_pagequeue *pq; boolean_t unchanged; u_short queue; vm_page_lock_assert(m, MA_NOTOWNED); if (vm_page_trylock(m)) return (TRUE); queue = m->queue; vm_pageout_init_marker(&marker, queue); pq = vm_page_pagequeue(m); TAILQ_INSERT_AFTER(&pq->pq_pl, m, &marker, plinks.q); vm_pagequeue_unlock(pq); vm_page_lock(m); vm_pagequeue_lock(pq); /* Page queue might have changed. */ *next = TAILQ_NEXT(&marker, plinks.q); unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q)); TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); return (unchanged); } /* * vm_pageout_clean: * * Clean the page and remove it from the laundry. * * We set the busy bit to cause potential page faults on this page to * block. Note the careful timing, however, the busy bit isn't set till * late and we cannot do anything that will mess with the page. */ static int vm_pageout_clean(vm_page_t m) { vm_object_t object; vm_page_t mc[2*vm_pageout_page_count], pb, ps; int pageout_count; int ib, is, page_base; vm_pindex_t pindex = m->pindex; vm_page_lock_assert(m, MA_OWNED); object = m->object; VM_OBJECT_ASSERT_WLOCKED(object); /* * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP * with the new swapper, but we could have serious problems paging * out other object types if there is insufficient memory. * * Unfortunately, checking free memory here is far too late, so the * check has been moved up a procedural level. */ /* * Can't clean the page if it's busy or held. */ vm_page_assert_unbusied(m); KASSERT(m->hold_count == 0, ("vm_pageout_clean: page %p is held", m)); vm_page_unlock(m); mc[vm_pageout_page_count] = pb = ps = m; pageout_count = 1; page_base = vm_pageout_page_count; ib = 1; is = 1; /* * Scan object for clusterable pages. * * We can cluster ONLY if: ->> the page is NOT * clean, wired, busy, held, or mapped into a * buffer, and one of the following: * 1) The page is inactive, or a seldom used * active page. * -or- * 2) we force the issue. * * During heavy mmap/modification loads the pageout * daemon can really fragment the underlying file * due to flushing pages out of order and not trying * align the clusters (which leave sporatic out-of-order * holes). To solve this problem we do the reverse scan * first and attempt to align our cluster, then do a * forward scan if room remains. */ more: while (ib && pageout_count < vm_pageout_page_count) { vm_page_t p; if (ib > pindex) { ib = 0; break; } if ((p = vm_page_prev(pb)) == NULL || vm_page_busied(p)) { ib = 0; break; } vm_page_lock(p); vm_page_test_dirty(p); if (p->dirty == 0 || p->queue != PQ_INACTIVE || p->hold_count != 0) { /* may be undergoing I/O */ vm_page_unlock(p); ib = 0; break; } vm_page_unlock(p); mc[--page_base] = pb = p; ++pageout_count; ++ib; /* * alignment boundry, stop here and switch directions. Do * not clear ib. */ if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) break; } while (pageout_count < vm_pageout_page_count && pindex + is < object->size) { vm_page_t p; if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p)) break; vm_page_lock(p); vm_page_test_dirty(p); if (p->dirty == 0 || p->queue != PQ_INACTIVE || p->hold_count != 0) { /* may be undergoing I/O */ vm_page_unlock(p); break; } vm_page_unlock(p); mc[page_base + pageout_count] = ps = p; ++pageout_count; ++is; } /* * If we exhausted our forward scan, continue with the reverse scan * when possible, even past a page boundry. This catches boundry * conditions. */ if (ib && pageout_count < vm_pageout_page_count) goto more; /* * we allow reads during pageouts... */ return (vm_pageout_flush(&mc[page_base], pageout_count, 0, 0, NULL, NULL)); } /* * vm_pageout_flush() - launder the given pages * * The given pages are laundered. Note that we setup for the start of * I/O ( i.e. busy the page ), mark it read-only, and bump the object * reference count all in here rather then in the parent. If we want * the parent to do more sophisticated things we may have to change * the ordering. * * Returned runlen is the count of pages between mreq and first * page after mreq with status VM_PAGER_AGAIN. * *eio is set to TRUE if pager returned VM_PAGER_ERROR or VM_PAGER_FAIL * for any page in runlen set. */ int vm_pageout_flush(vm_page_t *mc, int count, int flags, int mreq, int *prunlen, boolean_t *eio) { vm_object_t object = mc[0]->object; int pageout_status[count]; int numpagedout = 0; int i, runlen; VM_OBJECT_ASSERT_WLOCKED(object); /* * Initiate I/O. Bump the vm_page_t->busy counter and * mark the pages read-only. * * We do not have to fixup the clean/dirty bits here... we can * allow the pager to do it after the I/O completes. * * NOTE! mc[i]->dirty may be partial or fragmented due to an * edge case with file fragments. */ for (i = 0; i < count; i++) { KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush: partially invalid page %p index %d/%d", mc[i], i, count)); vm_page_sbusy(mc[i]); pmap_remove_write(mc[i]); } vm_object_pip_add(object, count); vm_pager_put_pages(object, mc, count, flags, pageout_status); runlen = count - mreq; if (eio != NULL) *eio = FALSE; for (i = 0; i < count; i++) { vm_page_t mt = mc[i]; KASSERT(pageout_status[i] == VM_PAGER_PEND || !pmap_page_is_write_mapped(mt), ("vm_pageout_flush: page %p is not write protected", mt)); switch (pageout_status[i]) { case VM_PAGER_OK: case VM_PAGER_PEND: numpagedout++; break; case VM_PAGER_BAD: /* * Page outside of range of object. Right now we * essentially lose the changes by pretending it * worked. */ vm_page_undirty(mt); break; case VM_PAGER_ERROR: case VM_PAGER_FAIL: /* * If page couldn't be paged out, then reactivate the * page so it doesn't clog the inactive list. (We * will try paging out it again later). */ vm_page_lock(mt); vm_page_activate(mt); vm_page_unlock(mt); if (eio != NULL && i >= mreq && i - mreq < runlen) *eio = TRUE; break; case VM_PAGER_AGAIN: if (i >= mreq && i - mreq < runlen) runlen = i - mreq; break; } /* * If the operation is still going, leave the page busy to * block all other accesses. Also, leave the paging in * progress indicator set so that we don't attempt an object * collapse. */ if (pageout_status[i] != VM_PAGER_PEND) { vm_object_pip_wakeup(object); vm_page_sunbusy(mt); if (vm_page_count_severe()) { vm_page_lock(mt); vm_page_try_to_cache(mt); vm_page_unlock(mt); } } } if (prunlen != NULL) *prunlen = runlen; return (numpagedout); } static boolean_t vm_pageout_launder(struct vm_pagequeue *pq, int tries, vm_paddr_t low, vm_paddr_t high) { struct mount *mp; struct vnode *vp; vm_object_t object; vm_paddr_t pa; vm_page_t m, m_tmp, next; int lockmode; vm_pagequeue_lock(pq); TAILQ_FOREACH_SAFE(m, &pq->pq_pl, plinks.q, next) { if ((m->flags & PG_MARKER) != 0) continue; pa = VM_PAGE_TO_PHYS(m); if (pa < low || pa + PAGE_SIZE > high) continue; if (!vm_pageout_page_lock(m, &next) || m->hold_count != 0) { vm_page_unlock(m); continue; } object = m->object; if ((!VM_OBJECT_TRYWLOCK(object) && (!vm_pageout_fallback_object_lock(m, &next) || m->hold_count != 0)) || vm_page_busied(m)) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); continue; } vm_page_test_dirty(m); if (m->dirty == 0 && object->ref_count != 0) pmap_remove_all(m); if (m->dirty != 0) { vm_page_unlock(m); if (tries == 0 || (object->flags & OBJ_DEAD) != 0) { VM_OBJECT_WUNLOCK(object); continue; } if (object->type == OBJT_VNODE) { vm_pagequeue_unlock(pq); vp = object->handle; vm_object_reference_locked(object); VM_OBJECT_WUNLOCK(object); (void)vn_start_write(vp, &mp, V_WAIT); lockmode = MNT_SHARED_WRITES(vp->v_mount) ? LK_SHARED : LK_EXCLUSIVE; vn_lock(vp, lockmode | LK_RETRY); VM_OBJECT_WLOCK(object); vm_object_page_clean(object, 0, 0, OBJPC_SYNC); VM_OBJECT_WUNLOCK(object); VOP_UNLOCK(vp, 0); vm_object_deallocate(object); vn_finished_write(mp); return (TRUE); } else if (object->type == OBJT_SWAP || object->type == OBJT_DEFAULT) { vm_pagequeue_unlock(pq); m_tmp = m; vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC, 0, NULL, NULL); VM_OBJECT_WUNLOCK(object); return (TRUE); } } else { /* * Dequeue here to prevent lock recursion in * vm_page_cache(). */ vm_page_dequeue_locked(m); vm_page_cache(m); vm_page_unlock(m); } VM_OBJECT_WUNLOCK(object); } vm_pagequeue_unlock(pq); return (FALSE); } /* * Increase the number of cached pages. The specified value, "tries", * determines which categories of pages are cached: * * 0: All clean, inactive pages within the specified physical address range * are cached. Will not sleep. * 1: The vm_lowmem handlers are called. All inactive pages within * the specified physical address range are cached. May sleep. * 2: The vm_lowmem handlers are called. All inactive and active pages * within the specified physical address range are cached. May sleep. */ void vm_pageout_grow_cache(int tries, vm_paddr_t low, vm_paddr_t high) { int actl, actmax, inactl, inactmax, dom, initial_dom; static int start_dom = 0; if (tries > 0) { /* * Decrease registered cache sizes. The vm_lowmem handlers * may acquire locks and/or sleep, so they can only be invoked * when "tries" is greater than zero. */ + SDT_PROBE0(vm, , , vm__lowmem_cache); EVENTHANDLER_INVOKE(vm_lowmem, 0); /* * We do this explicitly after the caches have been drained * above. */ uma_reclaim(); } /* * Make the next scan start on the next domain. */ initial_dom = atomic_fetchadd_int(&start_dom, 1) % vm_ndomains; inactl = 0; inactmax = cnt.v_inactive_count; actl = 0; actmax = tries < 2 ? 0 : cnt.v_active_count; dom = initial_dom; /* * Scan domains in round-robin order, first inactive queues, * then active. Since domain usually owns large physically * contiguous chunk of memory, it makes sense to completely * exhaust one domain before switching to next, while growing * the pool of contiguous physical pages. * * Do not even start launder a domain which cannot contain * the specified address range, as indicated by segments * constituting the domain. */ again: if (inactl < inactmax) { if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, low, high) && vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_INACTIVE], tries, low, high)) { inactl++; goto again; } if (++dom == vm_ndomains) dom = 0; if (dom != initial_dom) goto again; } if (actl < actmax) { if (vm_phys_domain_intersects(vm_dom[dom].vmd_segs, low, high) && vm_pageout_launder(&vm_dom[dom].vmd_pagequeues[PQ_ACTIVE], tries, low, high)) { actl++; goto again; } if (++dom == vm_ndomains) dom = 0; if (dom != initial_dom) goto again; } } #if !defined(NO_SWAPPING) /* * vm_pageout_object_deactivate_pages * * Deactivate enough pages to satisfy the inactive target * requirements. * * The object and map must be locked. */ static void vm_pageout_object_deactivate_pages(pmap_t pmap, vm_object_t first_object, long desired) { vm_object_t backing_object, object; vm_page_t p; int act_delta, remove_mode; VM_OBJECT_ASSERT_LOCKED(first_object); if ((first_object->flags & OBJ_FICTITIOUS) != 0) return; for (object = first_object;; object = backing_object) { if (pmap_resident_count(pmap) <= desired) goto unlock_return; VM_OBJECT_ASSERT_LOCKED(object); if ((object->flags & OBJ_UNMANAGED) != 0 || object->paging_in_progress != 0) goto unlock_return; remove_mode = 0; if (object->shadow_count > 1) remove_mode = 1; /* * Scan the object's entire memory queue. */ TAILQ_FOREACH(p, &object->memq, listq) { if (pmap_resident_count(pmap) <= desired) goto unlock_return; if (vm_page_busied(p)) continue; PCPU_INC(cnt.v_pdpages); vm_page_lock(p); if (p->wire_count != 0 || p->hold_count != 0 || !pmap_page_exists_quick(pmap, p)) { vm_page_unlock(p); continue; } act_delta = pmap_ts_referenced(p); if ((p->aflags & PGA_REFERENCED) != 0) { if (act_delta == 0) act_delta = 1; vm_page_aflag_clear(p, PGA_REFERENCED); } if (p->queue != PQ_ACTIVE && act_delta != 0) { vm_page_activate(p); p->act_count += act_delta; } else if (p->queue == PQ_ACTIVE) { if (act_delta == 0) { p->act_count -= min(p->act_count, ACT_DECLINE); if (!remove_mode && p->act_count == 0) { pmap_remove_all(p); vm_page_deactivate(p); } else vm_page_requeue(p); } else { vm_page_activate(p); if (p->act_count < ACT_MAX - ACT_ADVANCE) p->act_count += ACT_ADVANCE; vm_page_requeue(p); } } else if (p->queue == PQ_INACTIVE) pmap_remove_all(p); vm_page_unlock(p); } if ((backing_object = object->backing_object) == NULL) goto unlock_return; VM_OBJECT_RLOCK(backing_object); if (object != first_object) VM_OBJECT_RUNLOCK(object); } unlock_return: if (object != first_object) VM_OBJECT_RUNLOCK(object); } /* * deactivate some number of pages in a map, try to do it fairly, but * that is really hard to do. */ static void vm_pageout_map_deactivate_pages(map, desired) vm_map_t map; long desired; { vm_map_entry_t tmpe; vm_object_t obj, bigobj; int nothingwired; if (!vm_map_trylock(map)) return; bigobj = NULL; nothingwired = TRUE; /* * first, search out the biggest object, and try to free pages from * that. */ tmpe = map->header.next; while (tmpe != &map->header) { if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { obj = tmpe->object.vm_object; if (obj != NULL && VM_OBJECT_TRYRLOCK(obj)) { if (obj->shadow_count <= 1 && (bigobj == NULL || bigobj->resident_page_count < obj->resident_page_count)) { if (bigobj != NULL) VM_OBJECT_RUNLOCK(bigobj); bigobj = obj; } else VM_OBJECT_RUNLOCK(obj); } } if (tmpe->wired_count > 0) nothingwired = FALSE; tmpe = tmpe->next; } if (bigobj != NULL) { vm_pageout_object_deactivate_pages(map->pmap, bigobj, desired); VM_OBJECT_RUNLOCK(bigobj); } /* * Next, hunt around for other pages to deactivate. We actually * do this search sort of wrong -- .text first is not the best idea. */ tmpe = map->header.next; while (tmpe != &map->header) { if (pmap_resident_count(vm_map_pmap(map)) <= desired) break; if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { obj = tmpe->object.vm_object; if (obj != NULL) { VM_OBJECT_RLOCK(obj); vm_pageout_object_deactivate_pages(map->pmap, obj, desired); VM_OBJECT_RUNLOCK(obj); } } tmpe = tmpe->next; } #ifdef __ia64__ /* * Remove all non-wired, managed mappings if a process is swapped out. * This will free page table pages. */ if (desired == 0) pmap_remove_pages(map->pmap); #else /* * Remove all mappings if a process is swapped out, this will free page * table pages. */ if (desired == 0 && nothingwired) { pmap_remove(vm_map_pmap(map), vm_map_min(map), vm_map_max(map)); } #endif vm_map_unlock(map); } #endif /* !defined(NO_SWAPPING) */ /* * vm_pageout_scan does the dirty work for the pageout daemon. * * pass 0 - Update active LRU/deactivate pages * pass 1 - Move inactive to cache or free * pass 2 - Launder dirty pages */ static void vm_pageout_scan(struct vm_domain *vmd, int pass) { vm_page_t m, next; struct vm_pagequeue *pq; vm_object_t object; int act_delta, addl_page_shortage, deficit, maxscan, page_shortage; int vnodes_skipped = 0; int maxlaunder; int lockmode; boolean_t queues_locked; /* * If we need to reclaim memory ask kernel caches to return * some. We rate limit to avoid thrashing. */ if (vmd == &vm_dom[0] && pass > 0 && (ticks - lowmem_ticks) / hz >= lowmem_period) { /* * Decrease registered cache sizes. */ + SDT_PROBE0(vm, , , vm__lowmem_scan); EVENTHANDLER_INVOKE(vm_lowmem, 0); /* * We do this explicitly after the caches have been * drained above. */ uma_reclaim(); lowmem_ticks = ticks; } /* * The addl_page_shortage is the number of temporarily * stuck pages in the inactive queue. In other words, the * number of pages from the inactive count that should be * discounted in setting the target for the active queue scan. */ addl_page_shortage = 0; /* * Calculate the number of pages we want to either free or move * to the cache. */ if (pass > 0) { deficit = atomic_readandclear_int(&vm_pageout_deficit); page_shortage = vm_paging_target() + deficit; } else page_shortage = deficit = 0; /* * maxlaunder limits the number of dirty pages we flush per scan. * For most systems a smaller value (16 or 32) is more robust under * extreme memory and disk pressure because any unnecessary writes * to disk can result in extreme performance degredation. However, * systems with excessive dirty pages (especially when MAP_NOSYNC is * used) will die horribly with limited laundering. If the pageout * daemon cannot clean enough pages in the first pass, we let it go * all out in succeeding passes. */ if ((maxlaunder = vm_max_launder) <= 1) maxlaunder = 1; if (pass > 1) maxlaunder = 10000; /* * Start scanning the inactive queue for pages we can move to the * cache or free. The scan will stop when the target is reached or * we have scanned the entire inactive queue. Note that m->act_count * is not used to form decisions for the inactive queue, only for the * active queue. */ pq = &vmd->vmd_pagequeues[PQ_INACTIVE]; maxscan = pq->pq_cnt; vm_pagequeue_lock(pq); queues_locked = TRUE; for (m = TAILQ_FIRST(&pq->pq_pl); m != NULL && maxscan-- > 0 && page_shortage > 0; m = next) { vm_pagequeue_assert_locked(pq); KASSERT(queues_locked, ("unlocked queues")); KASSERT(m->queue == PQ_INACTIVE, ("Inactive queue %p", m)); PCPU_INC(cnt.v_pdpages); next = TAILQ_NEXT(m, plinks.q); /* * skip marker pages */ if (m->flags & PG_MARKER) continue; KASSERT((m->flags & PG_FICTITIOUS) == 0, ("Fictitious page %p cannot be in inactive queue", m)); KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("Unmanaged page %p cannot be in inactive queue", m)); /* * The page or object lock acquisitions fail if the * page was removed from the queue or moved to a * different position within the queue. In either * case, addl_page_shortage should not be incremented. */ if (!vm_pageout_page_lock(m, &next)) { vm_page_unlock(m); continue; } object = m->object; if (!VM_OBJECT_TRYWLOCK(object) && !vm_pageout_fallback_object_lock(m, &next)) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); continue; } /* * Don't mess with busy pages, keep them at at the * front of the queue, most likely they are being * paged out. Increment addl_page_shortage for busy * pages, because they may leave the inactive queue * shortly after page scan is finished. */ if (vm_page_busied(m)) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); addl_page_shortage++; continue; } /* * We unlock the inactive page queue, invalidating the * 'next' pointer. Use our marker to remember our * place. */ TAILQ_INSERT_AFTER(&pq->pq_pl, m, &vmd->vmd_marker, plinks.q); vm_pagequeue_unlock(pq); queues_locked = FALSE; /* * We bump the activation count if the page has been * referenced while in the inactive queue. This makes * it less likely that the page will be added back to the * inactive queue prematurely again. Here we check the * page tables (or emulated bits, if any), given the upper * level VM system not knowing anything about existing * references. */ act_delta = 0; if ((m->aflags & PGA_REFERENCED) != 0) { vm_page_aflag_clear(m, PGA_REFERENCED); act_delta = 1; } if (object->ref_count != 0) { act_delta += pmap_ts_referenced(m); } else { KASSERT(!pmap_page_is_mapped(m), ("vm_pageout_scan: page %p is mapped", m)); } /* * If the upper level VM system knows about any page * references, we reactivate the page or requeue it. */ if (act_delta != 0) { if (object->ref_count) { vm_page_activate(m); m->act_count += act_delta + ACT_ADVANCE; } else { vm_pagequeue_lock(pq); queues_locked = TRUE; vm_page_requeue_locked(m); } VM_OBJECT_WUNLOCK(object); vm_page_unlock(m); goto relock_queues; } if (m->hold_count != 0) { vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); /* * Held pages are essentially stuck in the * queue. So, they ought to be discounted * from the inactive count. See the * calculation of the page_shortage for the * loop over the active queue below. */ addl_page_shortage++; goto relock_queues; } /* * If the page appears to be clean at the machine-independent * layer, then remove all of its mappings from the pmap in * anticipation of placing it onto the cache queue. If, * however, any of the page's mappings allow write access, * then the page may still be modified until the last of those * mappings are removed. */ vm_page_test_dirty(m); if (m->dirty == 0 && object->ref_count != 0) pmap_remove_all(m); if (m->valid == 0) { /* * Invalid pages can be easily freed */ vm_page_free(m); PCPU_INC(cnt.v_dfree); --page_shortage; } else if (m->dirty == 0) { /* * Clean pages can be placed onto the cache queue. * This effectively frees them. */ vm_page_cache(m); --page_shortage; } else if ((m->flags & PG_WINATCFLS) == 0 && pass < 2) { /* * Dirty pages need to be paged out, but flushing * a page is extremely expensive verses freeing * a clean page. Rather then artificially limiting * the number of pages we can flush, we instead give * dirty pages extra priority on the inactive queue * by forcing them to be cycled through the queue * twice before being flushed, after which the * (now clean) page will cycle through once more * before being freed. This significantly extends * the thrash point for a heavily loaded machine. */ m->flags |= PG_WINATCFLS; vm_pagequeue_lock(pq); queues_locked = TRUE; vm_page_requeue_locked(m); } else if (maxlaunder > 0) { /* * We always want to try to flush some dirty pages if * we encounter them, to keep the system stable. * Normally this number is small, but under extreme * pressure where there are insufficient clean pages * on the inactive queue, we may have to go all out. */ int swap_pageouts_ok; struct vnode *vp = NULL; struct mount *mp = NULL; if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { swap_pageouts_ok = 1; } else { swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && vm_page_count_min()); } /* * We don't bother paging objects that are "dead". * Those objects are in a "rundown" state. */ if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { vm_pagequeue_lock(pq); vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); queues_locked = TRUE; vm_page_requeue_locked(m); goto relock_queues; } /* * The object is already known NOT to be dead. It * is possible for the vget() to block the whole * pageout daemon, but the new low-memory handling * code should prevent it. * * The previous code skipped locked vnodes and, worse, * reordered pages in the queue. This results in * completely non-deterministic operation and, on a * busy system, can lead to extremely non-optimal * pageouts. For example, it can cause clean pages * to be freed and dirty pages to be moved to the end * of the queue. Since dirty pages are also moved to * the end of the queue once-cleaned, this gives * way too large a weighting to defering the freeing * of dirty pages. * * We can't wait forever for the vnode lock, we might * deadlock due to a vn_read() getting stuck in * vm_wait while holding this vnode. We skip the * vnode if we can't get it in a reasonable amount * of time. */ if (object->type == OBJT_VNODE) { vm_page_unlock(m); vp = object->handle; if (vp->v_type == VREG && vn_start_write(vp, &mp, V_NOWAIT) != 0) { mp = NULL; ++pageout_lock_miss; if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; goto unlock_and_continue; } KASSERT(mp != NULL, ("vp %p with NULL v_mount", vp)); vm_object_reference_locked(object); VM_OBJECT_WUNLOCK(object); lockmode = MNT_SHARED_WRITES(vp->v_mount) ? LK_SHARED : LK_EXCLUSIVE; if (vget(vp, lockmode | LK_TIMELOCK, curthread)) { VM_OBJECT_WLOCK(object); ++pageout_lock_miss; if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; vp = NULL; goto unlock_and_continue; } VM_OBJECT_WLOCK(object); vm_page_lock(m); vm_pagequeue_lock(pq); queues_locked = TRUE; /* * The page might have been moved to another * queue during potential blocking in vget() * above. The page might have been freed and * reused for another vnode. */ if (m->queue != PQ_INACTIVE || m->object != object || TAILQ_NEXT(m, plinks.q) != &vmd->vmd_marker) { vm_page_unlock(m); if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; goto unlock_and_continue; } /* * The page may have been busied during the * blocking in vget(). We don't move the * page back onto the end of the queue so that * statistics are more correct if we don't. */ if (vm_page_busied(m)) { vm_page_unlock(m); addl_page_shortage++; goto unlock_and_continue; } /* * If the page has become held it might * be undergoing I/O, so skip it */ if (m->hold_count != 0) { vm_page_unlock(m); addl_page_shortage++; if (object->flags & OBJ_MIGHTBEDIRTY) vnodes_skipped++; goto unlock_and_continue; } vm_pagequeue_unlock(pq); queues_locked = FALSE; } /* * If a page is dirty, then it is either being washed * (but not yet cleaned) or it is still in the * laundry. If it is still in the laundry, then we * start the cleaning operation. * * decrement page_shortage on success to account for * the (future) cleaned page. Otherwise we could wind * up laundering or cleaning too many pages. */ if (vm_pageout_clean(m) != 0) { --page_shortage; --maxlaunder; } unlock_and_continue: vm_page_lock_assert(m, MA_NOTOWNED); VM_OBJECT_WUNLOCK(object); if (mp != NULL) { if (queues_locked) { vm_pagequeue_unlock(pq); queues_locked = FALSE; } if (vp != NULL) vput(vp); vm_object_deallocate(object); vn_finished_write(mp); } vm_page_lock_assert(m, MA_NOTOWNED); goto relock_queues; } vm_page_unlock(m); VM_OBJECT_WUNLOCK(object); relock_queues: if (!queues_locked) { vm_pagequeue_lock(pq); queues_locked = TRUE; } next = TAILQ_NEXT(&vmd->vmd_marker, plinks.q); TAILQ_REMOVE(&pq->pq_pl, &vmd->vmd_marker, plinks.q); } vm_pagequeue_unlock(pq); #if !defined(NO_SWAPPING) /* * Wakeup the swapout daemon if we didn't cache or free the targeted * number of pages. */ if (vm_swap_enabled && page_shortage > 0) vm_req_vmdaemon(VM_SWAP_NORMAL); #endif /* * Wakeup the sync daemon if we skipped a vnode in a writeable object * and we didn't cache or free enough pages. */ if (vnodes_skipped > 0 && page_shortage > cnt.v_free_target - cnt.v_free_min) (void)speedup_syncer(); /* * Compute the number of pages we want to try to move from the * active queue to the inactive queue. */ page_shortage = cnt.v_inactive_target - cnt.v_inactive_count + vm_paging_target() + deficit + addl_page_shortage; pq = &vmd->vmd_pagequeues[PQ_ACTIVE]; vm_pagequeue_lock(pq); maxscan = pq->pq_cnt; /* * If we're just idle polling attempt to visit every * active page within 'update_period' seconds. */ if (pass == 0 && vm_pageout_update_period != 0) { maxscan /= vm_pageout_update_period; page_shortage = maxscan; } /* * Scan the active queue for things we can deactivate. We nominally * track the per-page activity counter and use it to locate * deactivation candidates. */ m = TAILQ_FIRST(&pq->pq_pl); while (m != NULL && maxscan-- > 0 && page_shortage > 0) { KASSERT(m->queue == PQ_ACTIVE, ("vm_pageout_scan: page %p isn't active", m)); next = TAILQ_NEXT(m, plinks.q); if ((m->flags & PG_MARKER) != 0) { m = next; continue; } KASSERT((m->flags & PG_FICTITIOUS) == 0, ("Fictitious page %p cannot be in active queue", m)); KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("Unmanaged page %p cannot be in active queue", m)); if (!vm_pageout_page_lock(m, &next)) { vm_page_unlock(m); m = next; continue; } /* * The count for pagedaemon pages is done after checking the * page for eligibility... */ PCPU_INC(cnt.v_pdpages); /* * Check to see "how much" the page has been used. */ act_delta = 0; if (m->aflags & PGA_REFERENCED) { vm_page_aflag_clear(m, PGA_REFERENCED); act_delta += 1; } /* * Unlocked object ref count check. Two races are possible. * 1) The ref was transitioning to zero and we saw non-zero, * the pmap bits will be checked unnecessarily. * 2) The ref was transitioning to one and we saw zero. * The page lock prevents a new reference to this page so * we need not check the reference bits. */ if (m->object->ref_count != 0) act_delta += pmap_ts_referenced(m); /* * Advance or decay the act_count based on recent usage. */ if (act_delta) { m->act_count += ACT_ADVANCE + act_delta; if (m->act_count > ACT_MAX) m->act_count = ACT_MAX; } else { m->act_count -= min(m->act_count, ACT_DECLINE); act_delta = m->act_count; } /* * Move this page to the tail of the active or inactive * queue depending on usage. */ if (act_delta == 0) { /* Dequeue to avoid later lock recursion. */ vm_page_dequeue_locked(m); vm_page_deactivate(m); page_shortage--; } else vm_page_requeue_locked(m); vm_page_unlock(m); m = next; } vm_pagequeue_unlock(pq); #if !defined(NO_SWAPPING) /* * Idle process swapout -- run once per second. */ if (vm_swap_idle_enabled) { static long lsec; if (time_second != lsec) { vm_req_vmdaemon(VM_SWAP_IDLE); lsec = time_second; } } #endif /* * If we are critically low on one of RAM or swap and low on * the other, kill the largest process. However, we avoid * doing this on the first pass in order to give ourselves a * chance to flush out dirty vnode-backed pages and to allow * active pages to be moved to the inactive queue and reclaimed. */ vm_pageout_mightbe_oom(vmd, pass); } static int vm_pageout_oom_vote; /* * The pagedaemon threads randlomly select one to perform the * OOM. Trying to kill processes before all pagedaemons * failed to reach free target is premature. */ static void vm_pageout_mightbe_oom(struct vm_domain *vmd, int pass) { int old_vote; if (pass <= 1 || !((swap_pager_avail < 64 && vm_page_count_min()) || (swap_pager_full && vm_paging_target() > 0))) { if (vmd->vmd_oom) { vmd->vmd_oom = FALSE; atomic_subtract_int(&vm_pageout_oom_vote, 1); } return; } if (vmd->vmd_oom) return; vmd->vmd_oom = TRUE; old_vote = atomic_fetchadd_int(&vm_pageout_oom_vote, 1); if (old_vote != vm_ndomains - 1) return; /* * The current pagedaemon thread is the last in the quorum to * start OOM. Initiate the selection and signaling of the * victim. */ vm_pageout_oom(VM_OOM_MEM); /* * After one round of OOM terror, recall our vote. On the * next pass, current pagedaemon would vote again if the low * memory condition is still there, due to vmd_oom being * false. */ vmd->vmd_oom = FALSE; atomic_subtract_int(&vm_pageout_oom_vote, 1); } void vm_pageout_oom(int shortage) { struct proc *p, *bigproc; vm_offset_t size, bigsize; struct thread *td; struct vmspace *vm; /* * We keep the process bigproc locked once we find it to keep anyone * from messing with it; however, there is a possibility of * deadlock if process B is bigproc and one of it's child processes * attempts to propagate a signal to B while we are waiting for A's * lock while walking this list. To avoid this, we don't block on * the process lock but just skip a process if it is already locked. */ bigproc = NULL; bigsize = 0; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { int breakout; if (PROC_TRYLOCK(p) == 0) continue; /* * If this is a system, protected or killed process, skip it. */ if (p->p_state != PRS_NORMAL || (p->p_flag & (P_INEXEC | P_PROTECTED | P_SYSTEM)) || (p->p_pid == 1) || P_KILLED(p) || ((p->p_pid < 48) && (swap_pager_avail != 0))) { PROC_UNLOCK(p); continue; } /* * If the process is in a non-running type state, * don't touch it. Check all the threads individually. */ breakout = 0; FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); if (!TD_ON_RUNQ(td) && !TD_IS_RUNNING(td) && !TD_IS_SLEEPING(td) && !TD_IS_SUSPENDED(td)) { thread_unlock(td); breakout = 1; break; } thread_unlock(td); } if (breakout) { PROC_UNLOCK(p); continue; } /* * get the process size */ vm = vmspace_acquire_ref(p); if (vm == NULL) { PROC_UNLOCK(p); continue; } if (!vm_map_trylock_read(&vm->vm_map)) { vmspace_free(vm); PROC_UNLOCK(p); continue; } size = vmspace_swap_count(vm); vm_map_unlock_read(&vm->vm_map); if (shortage == VM_OOM_MEM) size += vmspace_resident_count(vm); vmspace_free(vm); /* * if the this process is bigger than the biggest one * remember it. */ if (size > bigsize) { if (bigproc != NULL) PROC_UNLOCK(bigproc); bigproc = p; bigsize = size; } else PROC_UNLOCK(p); } sx_sunlock(&allproc_lock); if (bigproc != NULL) { killproc(bigproc, "out of swap space"); sched_nice(bigproc, PRIO_MIN); PROC_UNLOCK(bigproc); wakeup(&cnt.v_free_count); } } static void vm_pageout_worker(void *arg) { struct vm_domain *domain; int domidx; domidx = (uintptr_t)arg; domain = &vm_dom[domidx]; /* * XXXKIB It could be useful to bind pageout daemon threads to * the cores belonging to the domain, from which vm_page_array * is allocated. */ KASSERT(domain->vmd_segs != 0, ("domain without segments")); vm_pageout_init_marker(&domain->vmd_marker, PQ_INACTIVE); /* * The pageout daemon worker is never done, so loop forever. */ while (TRUE) { /* * If we have enough free memory, wakeup waiters. Do * not clear vm_pages_needed until we reach our target, * otherwise we may be woken up over and over again and * waste a lot of cpu. */ mtx_lock(&vm_page_queue_free_mtx); if (vm_pages_needed && !vm_page_count_min()) { if (!vm_paging_needed()) vm_pages_needed = 0; wakeup(&cnt.v_free_count); } if (vm_pages_needed) { /* * Still not done, take a second pass without waiting * (unlimited dirty cleaning), otherwise sleep a bit * and try again. */ if (domain->vmd_pass > 1) msleep(&vm_pages_needed, &vm_page_queue_free_mtx, PVM, "psleep", hz / 2); } else { /* * Good enough, sleep until required to refresh * stats. */ domain->vmd_pass = 0; msleep(&vm_pages_needed, &vm_page_queue_free_mtx, PVM, "psleep", hz); } if (vm_pages_needed) { cnt.v_pdwakeups++; domain->vmd_pass++; } mtx_unlock(&vm_page_queue_free_mtx); vm_pageout_scan(domain, domain->vmd_pass); } } /* - * vm_pageout is the high level pageout daemon. + * vm_pageout_init initialises basic pageout daemon settings. */ static void -vm_pageout(void) +vm_pageout_init(void) { -#if MAXMEMDOM > 1 - int error, i; -#endif - /* * Initialize some paging parameters. */ cnt.v_interrupt_free_min = 2; if (cnt.v_page_count < 2000) vm_pageout_page_count = 8; /* * v_free_reserved needs to include enough for the largest * swap pager structures plus enough for any pv_entry structs * when paging. */ if (cnt.v_page_count > 1024) cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; else cnt.v_free_min = 4; cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + cnt.v_interrupt_free_min; cnt.v_free_reserved = vm_pageout_page_count + cnt.v_pageout_free_min + (cnt.v_page_count / 768); cnt.v_free_severe = cnt.v_free_min / 2; cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; cnt.v_free_min += cnt.v_free_reserved; cnt.v_free_severe += cnt.v_free_reserved; cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; if (cnt.v_inactive_target > cnt.v_free_count / 3) cnt.v_inactive_target = cnt.v_free_count / 3; /* * Set the default wakeup threshold to be 10% above the minimum * page limit. This keeps the steady state out of shortfall. */ vm_pageout_wakeup_thresh = (cnt.v_free_min / 10) * 11; /* * Set interval in seconds for active scan. We want to visit each * page at least once every ten minutes. This is to prevent worst * case paging behaviors with stale active LRU. */ if (vm_pageout_update_period == 0) vm_pageout_update_period = 600; /* XXX does not really belong here */ if (vm_page_max_wired == 0) vm_page_max_wired = cnt.v_free_count / 3; +} + +/* + * vm_pageout is the high level pageout daemon. + */ +static void +vm_pageout(void) +{ +#if MAXMEMDOM > 1 + int error, i; +#endif swap_pager_swap_init(); #if MAXMEMDOM > 1 for (i = 1; i < vm_ndomains; i++) { error = kthread_add(vm_pageout_worker, (void *)(uintptr_t)i, curproc, NULL, 0, 0, "dom%d", i); if (error != 0) { panic("starting pageout for domain %d, error %d\n", i, error); } } #endif vm_pageout_worker((void *)(uintptr_t)0); } /* * Unless the free page queue lock is held by the caller, this function * should be regarded as advisory. Specifically, the caller should * not msleep() on &cnt.v_free_count following this function unless * the free page queue lock is held until the msleep() is performed. */ void pagedaemon_wakeup(void) { if (!vm_pages_needed && curthread->td_proc != pageproc) { vm_pages_needed = 1; wakeup(&vm_pages_needed); } } #if !defined(NO_SWAPPING) static void vm_req_vmdaemon(int req) { static int lastrun = 0; mtx_lock(&vm_daemon_mtx); vm_pageout_req_swapout |= req; if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { wakeup(&vm_daemon_needed); lastrun = ticks; } mtx_unlock(&vm_daemon_mtx); } static void vm_daemon(void) { struct rlimit rsslim; struct proc *p; struct thread *td; struct vmspace *vm; int breakout, swapout_flags, tryagain, attempts; #ifdef RACCT uint64_t rsize, ravailable; #endif while (TRUE) { mtx_lock(&vm_daemon_mtx); #ifdef RACCT msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", hz); #else msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep", 0); #endif swapout_flags = vm_pageout_req_swapout; vm_pageout_req_swapout = 0; mtx_unlock(&vm_daemon_mtx); if (swapout_flags) swapout_procs(swapout_flags); /* * scan the processes for exceeding their rlimits or if * process is swapped out -- deactivate pages */ tryagain = 0; attempts = 0; again: attempts++; sx_slock(&allproc_lock); FOREACH_PROC_IN_SYSTEM(p) { vm_pindex_t limit, size; /* * if this is a system process or if we have already * looked at this process, skip it. */ PROC_LOCK(p); if (p->p_state != PRS_NORMAL || p->p_flag & (P_INEXEC | P_SYSTEM | P_WEXIT)) { PROC_UNLOCK(p); continue; } /* * if the process is in a non-running type state, * don't touch it. */ breakout = 0; FOREACH_THREAD_IN_PROC(p, td) { thread_lock(td); if (!TD_ON_RUNQ(td) && !TD_IS_RUNNING(td) && !TD_IS_SLEEPING(td) && !TD_IS_SUSPENDED(td)) { thread_unlock(td); breakout = 1; break; } thread_unlock(td); } if (breakout) { PROC_UNLOCK(p); continue; } /* * get a limit */ lim_rlimit(p, RLIMIT_RSS, &rsslim); limit = OFF_TO_IDX( qmin(rsslim.rlim_cur, rsslim.rlim_max)); /* * let processes that are swapped out really be * swapped out set the limit to nothing (will force a * swap-out.) */ if ((p->p_flag & P_INMEM) == 0) limit = 0; /* XXX */ vm = vmspace_acquire_ref(p); PROC_UNLOCK(p); if (vm == NULL) continue; size = vmspace_resident_count(vm); if (size >= limit) { vm_pageout_map_deactivate_pages( &vm->vm_map, limit); } #ifdef RACCT rsize = IDX_TO_OFF(size); PROC_LOCK(p); racct_set(p, RACCT_RSS, rsize); ravailable = racct_get_available(p, RACCT_RSS); PROC_UNLOCK(p); if (rsize > ravailable) { /* * Don't be overly aggressive; this might be * an innocent process, and the limit could've * been exceeded by some memory hog. Don't * try to deactivate more than 1/4th of process' * resident set size. */ if (attempts <= 8) { if (ravailable < rsize - (rsize / 4)) ravailable = rsize - (rsize / 4); } vm_pageout_map_deactivate_pages( &vm->vm_map, OFF_TO_IDX(ravailable)); /* Update RSS usage after paging out. */ size = vmspace_resident_count(vm); rsize = IDX_TO_OFF(size); PROC_LOCK(p); racct_set(p, RACCT_RSS, rsize); PROC_UNLOCK(p); if (rsize > ravailable) tryagain = 1; } #endif vmspace_free(vm); } sx_sunlock(&allproc_lock); if (tryagain != 0 && attempts <= 10) goto again; } } #endif /* !defined(NO_SWAPPING) */ Index: stable/10 =================================================================== --- stable/10 (revision 272874) +++ stable/10 (revision 272875) Property changes on: stable/10 ___________________________________________________________________ Modified: svn:mergeinfo ## -0,0 +0,1 ## Merged /head:r270759,270861,272483