diff --git a/module/os/freebsd/zfs/abd_os.c b/module/os/freebsd/zfs/abd_os.c index 8bc1ef1325e9..fa1034ff88bc 100644 --- a/module/os/freebsd/zfs/abd_os.c +++ b/module/os/freebsd/zfs/abd_os.c @@ -1,508 +1,509 @@ /* * This file and its contents are supplied under the terms of the * Common Development and Distribution License ("CDDL"), version 1.0. * You may only use this file in accordance with the terms of version * 1.0 of the CDDL. * * A full copy of the text of the CDDL should have accompanied this * source. A copy of the CDDL is also available via the Internet at * http://www.illumos.org/license/CDDL. */ /* * Copyright (c) 2014 by Chunwei Chen. All rights reserved. * Copyright (c) 2016 by Delphix. All rights reserved. */ /* * See abd.c for a general overview of the arc buffered data (ABD). * * Using a large proportion of scattered ABDs decreases ARC fragmentation since * when we are at the limit of allocatable space, using equal-size chunks will * allow us to quickly reclaim enough space for a new large allocation (assuming * it is also scattered). * * ABDs are allocated scattered by default unless the caller uses * abd_alloc_linear() or zfs_abd_scatter_enabled is disabled. */ #include #include #include #include #include #include typedef struct abd_stats { kstat_named_t abdstat_struct_size; kstat_named_t abdstat_scatter_cnt; kstat_named_t abdstat_scatter_data_size; kstat_named_t abdstat_scatter_chunk_waste; kstat_named_t abdstat_linear_cnt; kstat_named_t abdstat_linear_data_size; } abd_stats_t; static abd_stats_t abd_stats = { /* Amount of memory occupied by all of the abd_t struct allocations */ { "struct_size", KSTAT_DATA_UINT64 }, /* * The number of scatter ABDs which are currently allocated, excluding * ABDs which don't own their data (for instance the ones which were * allocated through abd_get_offset()). */ { "scatter_cnt", KSTAT_DATA_UINT64 }, /* Amount of data stored in all scatter ABDs tracked by scatter_cnt */ { "scatter_data_size", KSTAT_DATA_UINT64 }, /* * The amount of space wasted at the end of the last chunk across all * scatter ABDs tracked by scatter_cnt. */ { "scatter_chunk_waste", KSTAT_DATA_UINT64 }, /* * The number of linear ABDs which are currently allocated, excluding * ABDs which don't own their data (for instance the ones which were * allocated through abd_get_offset() and abd_get_from_buf()). If an * ABD takes ownership of its buf then it will become tracked. */ { "linear_cnt", KSTAT_DATA_UINT64 }, /* Amount of data stored in all linear ABDs tracked by linear_cnt */ { "linear_data_size", KSTAT_DATA_UINT64 }, }; struct { wmsum_t abdstat_struct_size; wmsum_t abdstat_scatter_cnt; wmsum_t abdstat_scatter_data_size; wmsum_t abdstat_scatter_chunk_waste; wmsum_t abdstat_linear_cnt; wmsum_t abdstat_linear_data_size; } abd_sums; /* * zfs_abd_scatter_min_size is the minimum allocation size to use scatter * ABD's for. Smaller allocations will use linear ABD's which use * zio_[data_]buf_alloc(). * * Scatter ABD's use at least one page each, so sub-page allocations waste * some space when allocated as scatter (e.g. 2KB scatter allocation wastes * half of each page). Using linear ABD's for small allocations means that * they will be put on slabs which contain many allocations. * * Linear ABDs for multi-page allocations are easier to use, and in some cases * it allows to avoid buffer copying. But allocation and especially free * of multi-page linear ABDs are expensive operations due to KVA mapping and * unmapping, and with time they cause KVA fragmentations. */ size_t zfs_abd_scatter_min_size = PAGE_SIZE + 1; #if defined(_KERNEL) SYSCTL_DECL(_vfs_zfs); SYSCTL_INT(_vfs_zfs, OID_AUTO, abd_scatter_enabled, CTLFLAG_RWTUN, &zfs_abd_scatter_enabled, 0, "Enable scattered ARC data buffers"); SYSCTL_ULONG(_vfs_zfs, OID_AUTO, abd_scatter_min_size, CTLFLAG_RWTUN, &zfs_abd_scatter_min_size, 0, "Minimum size of scatter allocations."); #endif kmem_cache_t *abd_chunk_cache; static kstat_t *abd_ksp; /* * We use a scattered SPA_MAXBLOCKSIZE sized ABD whose chunks are * just a single zero'd page-sized buffer. This allows us to conserve * memory by only using a single zero buffer for the scatter chunks. */ abd_t *abd_zero_scatter = NULL; static char *abd_zero_buf = NULL; static uint_t abd_chunkcnt_for_bytes(size_t size) { return ((size + PAGE_MASK) >> PAGE_SHIFT); } static inline uint_t abd_scatter_chunkcnt(abd_t *abd) { ASSERT(!abd_is_linear(abd)); return (abd_chunkcnt_for_bytes( ABD_SCATTER(abd).abd_offset + abd->abd_size)); } boolean_t abd_size_alloc_linear(size_t size) { return (!zfs_abd_scatter_enabled || size < zfs_abd_scatter_min_size); } void abd_update_scatter_stats(abd_t *abd, abd_stats_op_t op) { uint_t n = abd_scatter_chunkcnt(abd); ASSERT(op == ABDSTAT_INCR || op == ABDSTAT_DECR); int waste = (n << PAGE_SHIFT) - abd->abd_size; if (op == ABDSTAT_INCR) { ABDSTAT_BUMP(abdstat_scatter_cnt); ABDSTAT_INCR(abdstat_scatter_data_size, abd->abd_size); ABDSTAT_INCR(abdstat_scatter_chunk_waste, waste); arc_space_consume(waste, ARC_SPACE_ABD_CHUNK_WASTE); } else { ABDSTAT_BUMPDOWN(abdstat_scatter_cnt); ABDSTAT_INCR(abdstat_scatter_data_size, -(int)abd->abd_size); ABDSTAT_INCR(abdstat_scatter_chunk_waste, -waste); arc_space_return(waste, ARC_SPACE_ABD_CHUNK_WASTE); } } void abd_update_linear_stats(abd_t *abd, abd_stats_op_t op) { ASSERT(op == ABDSTAT_INCR || op == ABDSTAT_DECR); if (op == ABDSTAT_INCR) { ABDSTAT_BUMP(abdstat_linear_cnt); ABDSTAT_INCR(abdstat_linear_data_size, abd->abd_size); } else { ABDSTAT_BUMPDOWN(abdstat_linear_cnt); ABDSTAT_INCR(abdstat_linear_data_size, -(int)abd->abd_size); } } void abd_verify_scatter(abd_t *abd) { uint_t i, n; /* * There is no scatter linear pages in FreeBSD so there is * an error if the ABD has been marked as a linear page. */ ASSERT(!abd_is_linear_page(abd)); ASSERT3U(ABD_SCATTER(abd).abd_offset, <, PAGE_SIZE); n = abd_scatter_chunkcnt(abd); for (i = 0; i < n; i++) { ASSERT3P(ABD_SCATTER(abd).abd_chunks[i], !=, NULL); } } void abd_alloc_chunks(abd_t *abd, size_t size) { uint_t i, n; n = abd_chunkcnt_for_bytes(size); for (i = 0; i < n; i++) { ABD_SCATTER(abd).abd_chunks[i] = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE); } } void abd_free_chunks(abd_t *abd) { uint_t i, n; n = abd_scatter_chunkcnt(abd); for (i = 0; i < n; i++) { kmem_cache_free(abd_chunk_cache, ABD_SCATTER(abd).abd_chunks[i]); } } abd_t * abd_alloc_struct_impl(size_t size) { uint_t chunkcnt = abd_chunkcnt_for_bytes(size); /* * In the event we are allocating a gang ABD, the size passed in * will be 0. We must make sure to set abd_size to the size of an * ABD struct as opposed to an ABD scatter with 0 chunks. The gang * ABD struct allocation accounts for an additional 24 bytes over * a scatter ABD with 0 chunks. */ size_t abd_size = MAX(sizeof (abd_t), offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt])); abd_t *abd = kmem_alloc(abd_size, KM_PUSHPAGE); ASSERT3P(abd, !=, NULL); ABDSTAT_INCR(abdstat_struct_size, abd_size); return (abd); } void abd_free_struct_impl(abd_t *abd) { uint_t chunkcnt = abd_is_linear(abd) || abd_is_gang(abd) ? 0 : abd_scatter_chunkcnt(abd); ssize_t size = MAX(sizeof (abd_t), offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt])); kmem_free(abd, size); ABDSTAT_INCR(abdstat_struct_size, -size); } /* * Allocate scatter ABD of size SPA_MAXBLOCKSIZE, where * each chunk in the scatterlist will be set to abd_zero_buf. */ static void abd_alloc_zero_scatter(void) { uint_t i, n; n = abd_chunkcnt_for_bytes(SPA_MAXBLOCKSIZE); abd_zero_buf = kmem_cache_alloc(abd_chunk_cache, KM_PUSHPAGE); + bzero(abd_zero_buf, PAGE_SIZE); abd_zero_scatter = abd_alloc_struct(SPA_MAXBLOCKSIZE); abd_zero_scatter->abd_flags |= ABD_FLAG_OWNER | ABD_FLAG_ZEROS; abd_zero_scatter->abd_size = SPA_MAXBLOCKSIZE; ABD_SCATTER(abd_zero_scatter).abd_offset = 0; for (i = 0; i < n; i++) { ABD_SCATTER(abd_zero_scatter).abd_chunks[i] = abd_zero_buf; } ABDSTAT_BUMP(abdstat_scatter_cnt); ABDSTAT_INCR(abdstat_scatter_data_size, PAGE_SIZE); } static void abd_free_zero_scatter(void) { ABDSTAT_BUMPDOWN(abdstat_scatter_cnt); ABDSTAT_INCR(abdstat_scatter_data_size, -(int)PAGE_SIZE); abd_free_struct(abd_zero_scatter); abd_zero_scatter = NULL; kmem_cache_free(abd_chunk_cache, abd_zero_buf); } static int abd_kstats_update(kstat_t *ksp, int rw) { abd_stats_t *as = ksp->ks_data; if (rw == KSTAT_WRITE) return (EACCES); as->abdstat_struct_size.value.ui64 = wmsum_value(&abd_sums.abdstat_struct_size); as->abdstat_scatter_cnt.value.ui64 = wmsum_value(&abd_sums.abdstat_scatter_cnt); as->abdstat_scatter_data_size.value.ui64 = wmsum_value(&abd_sums.abdstat_scatter_data_size); as->abdstat_scatter_chunk_waste.value.ui64 = wmsum_value(&abd_sums.abdstat_scatter_chunk_waste); as->abdstat_linear_cnt.value.ui64 = wmsum_value(&abd_sums.abdstat_linear_cnt); as->abdstat_linear_data_size.value.ui64 = wmsum_value(&abd_sums.abdstat_linear_data_size); return (0); } void abd_init(void) { abd_chunk_cache = kmem_cache_create("abd_chunk", PAGE_SIZE, 0, NULL, NULL, NULL, NULL, 0, KMC_NODEBUG); wmsum_init(&abd_sums.abdstat_struct_size, 0); wmsum_init(&abd_sums.abdstat_scatter_cnt, 0); wmsum_init(&abd_sums.abdstat_scatter_data_size, 0); wmsum_init(&abd_sums.abdstat_scatter_chunk_waste, 0); wmsum_init(&abd_sums.abdstat_linear_cnt, 0); wmsum_init(&abd_sums.abdstat_linear_data_size, 0); abd_ksp = kstat_create("zfs", 0, "abdstats", "misc", KSTAT_TYPE_NAMED, sizeof (abd_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL); if (abd_ksp != NULL) { abd_ksp->ks_data = &abd_stats; abd_ksp->ks_update = abd_kstats_update; kstat_install(abd_ksp); } abd_alloc_zero_scatter(); } void abd_fini(void) { abd_free_zero_scatter(); if (abd_ksp != NULL) { kstat_delete(abd_ksp); abd_ksp = NULL; } wmsum_fini(&abd_sums.abdstat_struct_size); wmsum_fini(&abd_sums.abdstat_scatter_cnt); wmsum_fini(&abd_sums.abdstat_scatter_data_size); wmsum_fini(&abd_sums.abdstat_scatter_chunk_waste); wmsum_fini(&abd_sums.abdstat_linear_cnt); wmsum_fini(&abd_sums.abdstat_linear_data_size); kmem_cache_destroy(abd_chunk_cache); abd_chunk_cache = NULL; } void abd_free_linear_page(abd_t *abd) { /* * FreeBSD does not have scatter linear pages * so there is an error. */ VERIFY(0); } /* * If we're going to use this ABD for doing I/O using the block layer, the * consumer of the ABD data doesn't care if it's scattered or not, and we don't * plan to store this ABD in memory for a long period of time, we should * allocate the ABD type that requires the least data copying to do the I/O. * * Currently this is linear ABDs, however if ldi_strategy() can ever issue I/Os * using a scatter/gather list we should switch to that and replace this call * with vanilla abd_alloc(). */ abd_t * abd_alloc_for_io(size_t size, boolean_t is_metadata) { return (abd_alloc_linear(size, is_metadata)); } abd_t * abd_get_offset_scatter(abd_t *abd, abd_t *sabd, size_t off, size_t size) { abd_verify(sabd); ASSERT3U(off, <=, sabd->abd_size); size_t new_offset = ABD_SCATTER(sabd).abd_offset + off; size_t chunkcnt = abd_chunkcnt_for_bytes( (new_offset & PAGE_MASK) + size); ASSERT3U(chunkcnt, <=, abd_scatter_chunkcnt(sabd)); /* * If an abd struct is provided, it is only the minimum size. If we * need additional chunks, we need to allocate a new struct. */ if (abd != NULL && offsetof(abd_t, abd_u.abd_scatter.abd_chunks[chunkcnt]) > sizeof (abd_t)) { abd = NULL; } if (abd == NULL) abd = abd_alloc_struct(chunkcnt << PAGE_SHIFT); /* * Even if this buf is filesystem metadata, we only track that * if we own the underlying data buffer, which is not true in * this case. Therefore, we don't ever use ABD_FLAG_META here. */ ABD_SCATTER(abd).abd_offset = new_offset & PAGE_MASK; /* Copy the scatterlist starting at the correct offset */ (void) memcpy(&ABD_SCATTER(abd).abd_chunks, &ABD_SCATTER(sabd).abd_chunks[new_offset >> PAGE_SHIFT], chunkcnt * sizeof (void *)); return (abd); } /* * Initialize the abd_iter. */ void abd_iter_init(struct abd_iter *aiter, abd_t *abd) { ASSERT(!abd_is_gang(abd)); abd_verify(abd); aiter->iter_abd = abd; aiter->iter_pos = 0; aiter->iter_mapaddr = NULL; aiter->iter_mapsize = 0; } /* * This is just a helper function to see if we have exhausted the * abd_iter and reached the end. */ boolean_t abd_iter_at_end(struct abd_iter *aiter) { return (aiter->iter_pos == aiter->iter_abd->abd_size); } /* * Advance the iterator by a certain amount. Cannot be called when a chunk is * in use. This can be safely called when the aiter has already exhausted, in * which case this does nothing. */ void abd_iter_advance(struct abd_iter *aiter, size_t amount) { ASSERT3P(aiter->iter_mapaddr, ==, NULL); ASSERT0(aiter->iter_mapsize); /* There's nothing left to advance to, so do nothing */ if (abd_iter_at_end(aiter)) return; aiter->iter_pos += amount; } /* * Map the current chunk into aiter. This can be safely called when the aiter * has already exhausted, in which case this does nothing. */ void abd_iter_map(struct abd_iter *aiter) { void *paddr; ASSERT3P(aiter->iter_mapaddr, ==, NULL); ASSERT0(aiter->iter_mapsize); /* There's nothing left to iterate over, so do nothing */ if (abd_iter_at_end(aiter)) return; abd_t *abd = aiter->iter_abd; size_t offset = aiter->iter_pos; if (abd_is_linear(abd)) { aiter->iter_mapsize = abd->abd_size - offset; paddr = ABD_LINEAR_BUF(abd); } else { offset += ABD_SCATTER(abd).abd_offset; paddr = ABD_SCATTER(abd).abd_chunks[offset >> PAGE_SHIFT]; offset &= PAGE_MASK; aiter->iter_mapsize = MIN(PAGE_SIZE - offset, abd->abd_size - aiter->iter_pos); } aiter->iter_mapaddr = (char *)paddr + offset; } /* * Unmap the current chunk from aiter. This can be safely called when the aiter * has already exhausted, in which case this does nothing. */ void abd_iter_unmap(struct abd_iter *aiter) { if (!abd_iter_at_end(aiter)) { ASSERT3P(aiter->iter_mapaddr, !=, NULL); ASSERT3U(aiter->iter_mapsize, >, 0); } aiter->iter_mapaddr = NULL; aiter->iter_mapsize = 0; } void abd_cache_reap_now(void) { kmem_cache_reap_soon(abd_chunk_cache); }