Index: head/sys/kern/subr_blist.c =================================================================== --- head/sys/kern/subr_blist.c (revision 324419) +++ head/sys/kern/subr_blist.c (revision 324420) @@ -1,1330 +1,1292 @@ /*- * Copyright (c) 1998 Matthew Dillon. 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. * 3. 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 AUTHOR ``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 AUTHOR 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. */ /* * BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting * * This module implements a general bitmap allocator/deallocator. The * allocator eats around 2 bits per 'block'. The module does not * try to interpret the meaning of a 'block' other than to return * SWAPBLK_NONE on an allocation failure. * * A radix tree controls access to pieces of the bitmap, and includes * auxiliary information at each interior node about the availabilty of * contiguous free blocks in the subtree rooted at that node. Two radix * constants are involved: one for the size of the bitmaps contained in the * leaf nodes (BLIST_BMAP_RADIX), and one for the number of descendents of * each of the meta (interior) nodes (BLIST_META_RADIX). Each subtree is * associated with a range of blocks. The root of any subtree stores a * hint field that defines an upper bound on the size of the largest * allocation that can begin in the associated block range. A hint is an * upper bound on a potential allocation, but not necessarily a tight upper * bound. * * The radix tree also implements two collapsed states for meta nodes: * the ALL-ALLOCATED state and the ALL-FREE state. If a meta node is * in either of these two states, all information contained underneath * the node is considered stale. These states are used to optimize * allocation and freeing operations. * * The hinting greatly increases code efficiency for allocations while * the general radix structure optimizes both allocations and frees. The * radix tree should be able to operate well no matter how much * fragmentation there is and no matter how large a bitmap is used. * * The blist code wires all necessary memory at creation time. Neither * allocations nor frees require interaction with the memory subsystem. * The non-blocking features of the blist code are used in the swap code * (vm/swap_pager.c). * * LAYOUT: The radix tree is laid out recursively using a * linear array. Each meta node is immediately followed (laid out * sequentially in memory) by BLIST_META_RADIX lower level nodes. This * is a recursive structure but one that can be easily scanned through * a very simple 'skip' calculation. In order to support large radixes, * portions of the tree may reside outside our memory allocation. We * handle this with an early-termination optimization (when bighint is * set to -1) on the scan. The memory allocation is only large enough * to cover the number of blocks requested at creation time even if it * must be encompassed in larger root-node radix. * * NOTE: the allocator cannot currently allocate more than * BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too * large' if you try. This is an area that could use improvement. The * radix is large enough that this restriction does not effect the swap * system, though. Currently only the allocation code is affected by * this algorithmic unfeature. The freeing code can handle arbitrary * ranges. * * This code can be compiled stand-alone for debugging. */ #include __FBSDID("$FreeBSD$"); #ifdef _KERNEL #include #include #include #include #include #include #include #include #include #else #ifndef BLIST_NO_DEBUG #define BLIST_DEBUG #endif #include #include #include #include #include +#include #include #include #include #define bitcount64(x) __bitcount64((uint64_t)(x)) #define malloc(a,b,c) calloc(a, 1) #define free(a,b) free(a) static __inline int imax(int a, int b) { return (a > b ? a : b); } #include void panic(const char *ctl, ...); #endif /* * static support functions */ static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count); static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t cursor, daddr_t count, u_daddr_t radix); static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count); static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, u_daddr_t radix); static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, blist_t dest, daddr_t count); static daddr_t blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count); static daddr_t blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count, u_daddr_t radix); -static daddr_t blst_radix_init(blmeta_t *scan, daddr_t radix, daddr_t count); #ifndef _KERNEL static void blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int tab); #endif #ifdef _KERNEL static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space"); #endif _Static_assert(BLIST_BMAP_RADIX % BLIST_META_RADIX == 0, "radix divisibility error"); #define BLIST_BMAP_MASK (BLIST_BMAP_RADIX - 1) #define BLIST_META_MASK (BLIST_META_RADIX - 1) /* * For a subtree that can represent the state of up to 'radix' blocks, the * number of leaf nodes of the subtree is L=radix/BLIST_BMAP_RADIX. If 'm' * is short for BLIST_META_RADIX, then for a tree of height h with L=m**h * leaf nodes, the total number of tree nodes is 1 + m + m**2 + ... + m**h, * or, equivalently, (m**(h+1)-1)/(m-1). This quantity is called 'skip' * in the 'meta' functions that process subtrees. Since integer division * discards remainders, we can express this computation as * skip = (m * m**h) / (m - 1) * skip = (m * (radix / BLIST_BMAP_RADIX)) / (m - 1) * and since m divides BLIST_BMAP_RADIX, we can simplify further to * skip = (radix / (BLIST_BMAP_RADIX / m)) / (m - 1) * skip = radix / ((BLIST_BMAP_RADIX / m) * (m - 1)) * so that simple integer division by a constant can safely be used for the * calculation. */ static inline daddr_t radix_to_skip(daddr_t radix) { return (radix / ((BLIST_BMAP_RADIX / BLIST_META_RADIX) * BLIST_META_MASK)); } /* * Use binary search, or a faster method, to find the 1 bit in a u_daddr_t. * Assumes that the argument has only one bit set. */ static inline int bitpos(u_daddr_t mask) { int hi, lo, mid; switch (sizeof(mask)) { #ifdef HAVE_INLINE_FFSLL case sizeof(long long): return (ffsll(mask) - 1); #endif default: lo = 0; hi = BLIST_BMAP_RADIX; while (lo + 1 < hi) { mid = (lo + hi) >> 1; if ((mask >> mid) != 0) lo = mid; else hi = mid; } return (lo); } } /* * blist_create() - create a blist capable of handling up to the specified * number of blocks * * blocks - must be greater than 0 * flags - malloc flags * * The smallest blist consists of a single leaf node capable of * managing BLIST_BMAP_RADIX blocks. */ blist_t blist_create(daddr_t blocks, int flags) { blist_t bl; - daddr_t nodes, radix; + daddr_t i, last_block; + u_daddr_t nodes, radix, skip; + int digit; /* - * Calculate the radix field used for scanning. + * Calculate the radix and node count used for scanning. Find the last + * block that is followed by a terminator. */ + last_block = blocks - 1; radix = BLIST_BMAP_RADIX; while (radix < blocks) { + if (((last_block / radix + 1) & BLIST_META_MASK) != 0) + /* + * A terminator will be added. Update last_block to the + * position just before that terminator. + */ + last_block |= radix - 1; radix *= BLIST_META_RADIX; } - nodes = 1 + blst_radix_init(NULL, radix, blocks); - bl = malloc(sizeof(struct blist), M_SWAP, flags); + /* + * Count the meta-nodes in the expanded tree, including the final + * terminator, from the bottom level up to the root. + */ + nodes = (last_block >= blocks) ? 2 : 1; + last_block /= BLIST_BMAP_RADIX; + while (last_block > 0) { + nodes += last_block + 1; + last_block /= BLIST_META_RADIX; + } + bl = malloc(offsetof(struct blist, bl_root[nodes]), M_SWAP, flags); if (bl == NULL) return (NULL); bl->bl_blocks = blocks; bl->bl_radix = radix; bl->bl_cursor = 0; - bl->bl_root = malloc(nodes * sizeof(blmeta_t), M_SWAP, flags); - if (bl->bl_root == NULL) { - free(bl, M_SWAP); - return (NULL); + + /* + * Initialize the empty tree by filling in root values, then initialize + * just the terminators in the rest of the tree. + */ + bl->bl_root[0].bm_bighint = 0; + if (radix == BLIST_BMAP_RADIX) + bl->bl_root[0].u.bmu_bitmap = 0; + else + bl->bl_root[0].u.bmu_avail = 0; + last_block = blocks - 1; + i = 0; + while (radix > BLIST_BMAP_RADIX) { + radix /= BLIST_META_RADIX; + skip = radix_to_skip(radix); + digit = last_block / radix; + i += 1 + digit * skip; + if (digit != BLIST_META_MASK) { + /* + * Add a terminator. + */ + bl->bl_root[i + skip].bm_bighint = (daddr_t)-1; + bl->bl_root[i + skip].u.bmu_bitmap = 0; + } + last_block %= radix; } - blst_radix_init(bl->bl_root, radix, blocks); #if defined(BLIST_DEBUG) printf( "BLIST representing %lld blocks (%lld MB of swap)" ", requiring %lldK of ram\n", (long long)bl->bl_blocks, (long long)bl->bl_blocks * 4 / 1024, (long long)(nodes * sizeof(blmeta_t) + 1023) / 1024 ); printf("BLIST raw radix tree contains %lld records\n", (long long)nodes); #endif return (bl); } void blist_destroy(blist_t bl) { - free(bl->bl_root, M_SWAP); + free(bl, M_SWAP); } /* * blist_alloc() - reserve space in the block bitmap. Return the base * of a contiguous region or SWAPBLK_NONE if space could * not be allocated. */ daddr_t blist_alloc(blist_t bl, daddr_t count) { daddr_t blk; /* * This loop iterates at most twice. An allocation failure in the * first iteration leads to a second iteration only if the cursor was * non-zero. When the cursor is zero, an allocation failure will * reduce the hint, stopping further iterations. */ while (count <= bl->bl_root->bm_bighint) { blk = blst_meta_alloc(bl->bl_root, bl->bl_cursor, count, bl->bl_radix); if (blk != SWAPBLK_NONE) { bl->bl_cursor = blk + count; if (bl->bl_cursor == bl->bl_blocks) bl->bl_cursor = 0; return (blk); } else if (bl->bl_cursor != 0) bl->bl_cursor = 0; } return (SWAPBLK_NONE); } /* * blist_avail() - return the number of free blocks. */ daddr_t blist_avail(blist_t bl) { if (bl->bl_radix == BLIST_BMAP_RADIX) return (bitcount64(bl->bl_root->u.bmu_bitmap)); else return (bl->bl_root->u.bmu_avail); } /* * blist_free() - free up space in the block bitmap. Return the base * of a contiguous region. Panic if an inconsistancy is * found. */ void blist_free(blist_t bl, daddr_t blkno, daddr_t count) { blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix); } /* * blist_fill() - mark a region in the block bitmap as off-limits * to the allocator (i.e. allocate it), ignoring any * existing allocations. Return the number of blocks * actually filled that were free before the call. */ daddr_t blist_fill(blist_t bl, daddr_t blkno, daddr_t count) { return (blst_meta_fill(bl->bl_root, blkno, count, bl->bl_radix)); } /* * blist_resize() - resize an existing radix tree to handle the * specified number of blocks. This will reallocate * the tree and transfer the previous bitmap to the new * one. When extending the tree you can specify whether * the new blocks are to left allocated or freed. */ void blist_resize(blist_t *pbl, daddr_t count, int freenew, int flags) { blist_t newbl = blist_create(count, flags); blist_t save = *pbl; *pbl = newbl; if (count > save->bl_blocks) count = save->bl_blocks; blst_copy(save->bl_root, 0, save->bl_radix, newbl, count); /* * If resizing upwards, should we free the new space or not? */ if (freenew && count < newbl->bl_blocks) { blist_free(newbl, count, newbl->bl_blocks - count); } blist_destroy(save); } #ifdef BLIST_DEBUG /* * blist_print() - dump radix tree */ void blist_print(blist_t bl) { printf("BLIST cursor = %08jx {\n", (uintmax_t)bl->bl_cursor); blst_radix_print(bl->bl_root, 0, bl->bl_radix, 4); printf("}\n"); } #endif static const u_daddr_t fib[] = { 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309, 3524578, }; /* * Use 'gap' to describe a maximal range of unallocated blocks/bits. */ struct gap_stats { daddr_t start; /* current gap start, or SWAPBLK_NONE */ daddr_t num; /* number of gaps observed */ daddr_t max; /* largest gap size */ daddr_t avg; /* average gap size */ daddr_t err; /* sum - num * avg */ daddr_t histo[nitems(fib)]; /* # gaps in each size range */ int max_bucket; /* last histo elt with nonzero val */ }; /* * gap_stats_counting() - is the state 'counting 1 bits'? * or 'skipping 0 bits'? */ static inline bool gap_stats_counting(const struct gap_stats *stats) { return (stats->start != SWAPBLK_NONE); } /* * init_gap_stats() - initialize stats on gap sizes */ static inline void init_gap_stats(struct gap_stats *stats) { bzero(stats, sizeof(*stats)); stats->start = SWAPBLK_NONE; } /* * update_gap_stats() - update stats on gap sizes */ static void update_gap_stats(struct gap_stats *stats, daddr_t posn) { daddr_t size; int hi, lo, mid; if (!gap_stats_counting(stats)) { stats->start = posn; return; } size = posn - stats->start; stats->start = SWAPBLK_NONE; if (size > stats->max) stats->max = size; /* * Find the fibonacci range that contains size, * expecting to find it in an early range. */ lo = 0; hi = 1; while (hi < nitems(fib) && fib[hi] <= size) { lo = hi; hi *= 2; } if (hi >= nitems(fib)) hi = nitems(fib); while (lo + 1 != hi) { mid = (lo + hi) >> 1; if (fib[mid] <= size) lo = mid; else hi = mid; } stats->histo[lo]++; if (lo > stats->max_bucket) stats->max_bucket = lo; stats->err += size - stats->avg; stats->num++; stats->avg += stats->err / stats->num; stats->err %= stats->num; } /* * dump_gap_stats() - print stats on gap sizes */ static inline void dump_gap_stats(const struct gap_stats *stats, struct sbuf *s) { int i; sbuf_printf(s, "number of maximal free ranges: %jd\n", (intmax_t)stats->num); sbuf_printf(s, "largest free range: %jd\n", (intmax_t)stats->max); sbuf_printf(s, "average maximal free range size: %jd\n", (intmax_t)stats->avg); sbuf_printf(s, "number of maximal free ranges of different sizes:\n"); sbuf_printf(s, " count | size range\n"); sbuf_printf(s, " ----- | ----------\n"); for (i = 0; i < stats->max_bucket; i++) { if (stats->histo[i] != 0) { sbuf_printf(s, "%20jd | ", (intmax_t)stats->histo[i]); if (fib[i] != fib[i + 1] - 1) sbuf_printf(s, "%jd to %jd\n", (intmax_t)fib[i], (intmax_t)fib[i + 1] - 1); else sbuf_printf(s, "%jd\n", (intmax_t)fib[i]); } } sbuf_printf(s, "%20jd | ", (intmax_t)stats->histo[i]); if (stats->histo[i] > 1) sbuf_printf(s, "%jd to %jd\n", (intmax_t)fib[i], (intmax_t)stats->max); else sbuf_printf(s, "%jd\n", (intmax_t)stats->max); } /* * blist_stats() - dump radix tree stats */ void blist_stats(blist_t bl, struct sbuf *s) { struct gap_stats gstats; struct gap_stats *stats = &gstats; daddr_t i, nodes, radix; u_daddr_t bit, diff, mask; init_gap_stats(stats); nodes = 0; i = bl->bl_radix; while (i < bl->bl_radix + bl->bl_blocks) { /* * Find max size subtree starting at i. */ radix = BLIST_BMAP_RADIX; while (((i / radix) & BLIST_META_MASK) == 0) radix *= BLIST_META_RADIX; /* * Check for skippable subtrees starting at i. */ while (radix > BLIST_BMAP_RADIX) { if (bl->bl_root[nodes].u.bmu_avail == 0) { if (gap_stats_counting(stats)) update_gap_stats(stats, i); break; } if (bl->bl_root[nodes].u.bmu_avail == radix) { if (!gap_stats_counting(stats)) update_gap_stats(stats, i); break; } /* * Skip subtree root. */ nodes++; radix /= BLIST_META_RADIX; } if (radix == BLIST_BMAP_RADIX) { /* * Scan leaf. */ mask = bl->bl_root[nodes].u.bmu_bitmap; diff = mask ^ (mask << 1); if (gap_stats_counting(stats)) diff ^= 1; while (diff != 0) { bit = diff & -diff; update_gap_stats(stats, i + bitpos(bit)); diff ^= bit; } } nodes += radix_to_skip(radix); i += radix; } update_gap_stats(stats, i); dump_gap_stats(stats, s); } /************************************************************************ * ALLOCATION SUPPORT FUNCTIONS * ************************************************************************ * * These support functions do all the actual work. They may seem * rather longish, but that's because I've commented them up. The * actual code is straight forward. * */ /* * blist_leaf_alloc() - allocate at a leaf in the radix tree (a bitmap). * * This is the core of the allocator and is optimized for the * BLIST_BMAP_RADIX block allocation case. Otherwise, execution * time is proportional to log2(count) + bitpos time. */ static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count) { u_daddr_t mask; int count1, hi, lo, num_shifts, range1, range_ext; range1 = 0; count1 = count - 1; num_shifts = fls(count1); mask = scan->u.bmu_bitmap; while ((-mask & ~mask) != 0 && num_shifts > 0) { /* * If bit i is set in mask, then bits in [i, i+range1] are set * in scan->u.bmu_bitmap. The value of range1 is equal to * count1 >> num_shifts. Grow range and reduce num_shifts to 0, * while preserving these invariants. The updates to mask leave * fewer bits set, but each bit that remains set represents a * longer string of consecutive bits set in scan->u.bmu_bitmap. * If more updates to mask cannot clear more bits, because mask * is partitioned with all 0 bits preceding all 1 bits, the loop * terminates immediately. */ num_shifts--; range_ext = range1 + ((count1 >> num_shifts) & 1); /* * mask is a signed quantity for the shift because when it is * shifted right, the sign bit should copied; when the last * block of the leaf is free, pretend, for a while, that all the * blocks that follow it are also free. */ mask &= (daddr_t)mask >> range_ext; range1 += range_ext; } if (mask == 0) { /* * Update bighint. There is no allocation bigger than range1 * starting in this leaf. */ scan->bm_bighint = range1; return (SWAPBLK_NONE); } /* Discard any candidates that appear before blk. */ mask &= (u_daddr_t)-1 << (blk & BLIST_BMAP_MASK); if (mask == 0) return (SWAPBLK_NONE); /* * The least significant set bit in mask marks the start of the first * available range of sufficient size. Clear all the bits but that one, * and then find its position. */ mask &= -mask; lo = bitpos(mask); hi = lo + count; if (hi > BLIST_BMAP_RADIX) { /* * An allocation within this leaf is impossible, so a successful * allocation depends on the next leaf providing some of the blocks. */ if (((blk / BLIST_BMAP_RADIX + 1) & BLIST_META_MASK) == 0) { /* * The next leaf has a different meta-node parent, so it * is not necessarily initialized. Update bighint, * comparing the range found at the end of mask to the * largest earlier range that could have been made to * vanish in the initial processing of mask. */ scan->bm_bighint = imax(BLIST_BMAP_RADIX - lo, range1); return (SWAPBLK_NONE); } hi -= BLIST_BMAP_RADIX; if (((scan[1].u.bmu_bitmap + 1) & ~((u_daddr_t)-1 << hi)) != 0) { /* * The next leaf doesn't have enough free blocks at the * beginning to complete the spanning allocation. The * hint cannot be updated, because the same allocation * request could be satisfied later, by this leaf, if * the state of the next leaf changes, and without any * changes to this leaf. */ return (SWAPBLK_NONE); } /* Clear the first 'hi' bits in the next leaf, allocating them. */ scan[1].u.bmu_bitmap &= (u_daddr_t)-1 << hi; hi = BLIST_BMAP_RADIX; } /* Set the bits of mask at position 'lo' and higher. */ mask = -mask; if (hi == BLIST_BMAP_RADIX) { /* * Update bighint. There is no allocation bigger than range1 * available in this leaf after this allocation completes. */ scan->bm_bighint = range1; } else { /* Clear the bits of mask at position 'hi' and higher. */ mask &= (u_daddr_t)-1 >> (BLIST_BMAP_RADIX - hi); /* If this allocation uses all the bits, clear the hint. */ if (mask == scan->u.bmu_bitmap) scan->bm_bighint = 0; } /* Clear the allocated bits from this leaf. */ scan->u.bmu_bitmap &= ~mask; return ((blk & ~BLIST_BMAP_MASK) + lo); } /* * blist_meta_alloc() - allocate at a meta in the radix tree. * * Attempt to allocate at a meta node. If we can't, we update * bighint and return a failure. Updating bighint optimize future * calls that hit this node. We have to check for our collapse cases * and we have a few optimizations strewn in as well. */ static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t cursor, daddr_t count, u_daddr_t radix) { daddr_t blk, i, next_skip, r, skip; int child; bool scan_from_start; if (radix == BLIST_BMAP_RADIX) return (blst_leaf_alloc(scan, cursor, count)); if (scan->u.bmu_avail < count) { /* * The meta node's hint must be too large if the allocation * exceeds the number of free blocks. Reduce the hint, and * return failure. */ scan->bm_bighint = scan->u.bmu_avail; return (SWAPBLK_NONE); } blk = cursor & -radix; skip = radix_to_skip(radix); next_skip = skip / BLIST_META_RADIX; /* * An ALL-FREE meta node requires special handling before allocating * any of its blocks. */ if (scan->u.bmu_avail == radix) { radix /= BLIST_META_RADIX; /* * Reinitialize each of the meta node's children. An ALL-FREE * meta node cannot have a terminator in any subtree. */ for (i = 1; i < skip; i += next_skip) { if (next_skip == 1) scan[i].u.bmu_bitmap = (u_daddr_t)-1; else scan[i].u.bmu_avail = radix; scan[i].bm_bighint = radix; } } else { radix /= BLIST_META_RADIX; } if (count > radix) { /* * The allocation exceeds the number of blocks that are * managed by a subtree of this meta node. */ panic("allocation too large"); } scan_from_start = cursor == blk; child = (cursor - blk) / radix; blk += child * radix; for (i = 1 + child * next_skip; i < skip; i += next_skip) { if (count <= scan[i].bm_bighint) { /* * The allocation might fit beginning in the i'th subtree. */ r = blst_meta_alloc(&scan[i], cursor > blk ? cursor : blk, count, radix); if (r != SWAPBLK_NONE) { scan->u.bmu_avail -= count; return (r); } } else if (scan[i].bm_bighint == (daddr_t)-1) { /* * Terminator */ break; } blk += radix; } /* * We couldn't allocate count in this subtree, update bighint. */ if (scan_from_start && scan->bm_bighint >= count) scan->bm_bighint = count - 1; return (SWAPBLK_NONE); } /* * BLST_LEAF_FREE() - free allocated block from leaf bitmap * */ static void blst_leaf_free(blmeta_t *scan, daddr_t blk, int count) { u_daddr_t mask; int n; /* * free some data in this bitmap * mask=0000111111111110000 * \_________/\__/ * count n */ n = blk & BLIST_BMAP_MASK; mask = ((u_daddr_t)-1 << n) & ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n)); if (scan->u.bmu_bitmap & mask) panic("freeing free block"); scan->u.bmu_bitmap |= mask; /* * We could probably do a better job here. We are required to make * bighint at least as large as the biggest contiguous block of * data. If we just shoehorn it, a little extra overhead will * be incured on the next allocation (but only that one typically). */ scan->bm_bighint = BLIST_BMAP_RADIX; } /* * BLST_META_FREE() - free allocated blocks from radix tree meta info * * This support routine frees a range of blocks from the bitmap. * The range must be entirely enclosed by this radix node. If a * meta node, we break the range down recursively to free blocks * in subnodes (which means that this code can free an arbitrary * range whereas the allocation code cannot allocate an arbitrary * range). */ static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, u_daddr_t radix) { daddr_t blk, i, next_skip, skip, v; int child; if (scan->bm_bighint == (daddr_t)-1) panic("freeing invalid range"); if (radix == BLIST_BMAP_RADIX) return (blst_leaf_free(scan, freeBlk, count)); skip = radix_to_skip(radix); next_skip = skip / BLIST_META_RADIX; if (scan->u.bmu_avail == 0) { /* * ALL-ALLOCATED special case, with possible * shortcut to ALL-FREE special case. */ scan->u.bmu_avail = count; scan->bm_bighint = count; if (count != radix) { for (i = 1; i < skip; i += next_skip) { if (scan[i].bm_bighint == (daddr_t)-1) break; scan[i].bm_bighint = 0; if (next_skip == 1) { scan[i].u.bmu_bitmap = 0; } else { scan[i].u.bmu_avail = 0; } } /* fall through */ } } else { scan->u.bmu_avail += count; /* scan->bm_bighint = radix; */ } /* * ALL-FREE special case. */ if (scan->u.bmu_avail == radix) return; if (scan->u.bmu_avail > radix) panic("blst_meta_free: freeing already free blocks (%lld) %lld/%lld", (long long)count, (long long)scan->u.bmu_avail, (long long)radix); /* * Break the free down into its components */ blk = freeBlk & -radix; radix /= BLIST_META_RADIX; child = (freeBlk - blk) / radix; blk += child * radix; i = 1 + child * next_skip; while (i < skip && blk < freeBlk + count) { v = blk + radix - freeBlk; if (v > count) v = count; blst_meta_free(&scan[i], freeBlk, v, radix); if (scan->bm_bighint < scan[i].bm_bighint) scan->bm_bighint = scan[i].bm_bighint; count -= v; freeBlk += v; blk += radix; i += next_skip; } } /* * BLIST_RADIX_COPY() - copy one radix tree to another * * Locates free space in the source tree and frees it in the destination * tree. The space may not already be free in the destination. */ static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, blist_t dest, daddr_t count) { daddr_t i, next_skip, skip; /* * Leaf node */ if (radix == BLIST_BMAP_RADIX) { u_daddr_t v = scan->u.bmu_bitmap; if (v == (u_daddr_t)-1) { blist_free(dest, blk, count); } else if (v != 0) { int i; for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) { if (v & ((u_daddr_t)1 << i)) blist_free(dest, blk + i, 1); } } return; } /* * Meta node */ if (scan->u.bmu_avail == 0) { /* * Source all allocated, leave dest allocated */ return; } if (scan->u.bmu_avail == radix) { /* * Source all free, free entire dest */ if (count < radix) blist_free(dest, blk, count); else blist_free(dest, blk, radix); return; } skip = radix_to_skip(radix); next_skip = skip / BLIST_META_RADIX; radix /= BLIST_META_RADIX; for (i = 1; count && i < skip; i += next_skip) { if (scan[i].bm_bighint == (daddr_t)-1) break; if (count >= radix) { blst_copy(&scan[i], blk, radix, dest, radix); count -= radix; } else { if (count) { blst_copy(&scan[i], blk, radix, dest, count); } count = 0; } blk += radix; } } /* * BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap * * This routine allocates all blocks in the specified range * regardless of any existing allocations in that range. Returns * the number of blocks allocated by the call. */ static daddr_t blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count) { daddr_t nblks; u_daddr_t mask; int n; n = blk & BLIST_BMAP_MASK; mask = ((u_daddr_t)-1 << n) & ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n)); /* Count the number of blocks that we are allocating. */ nblks = bitcount64(scan->u.bmu_bitmap & mask); scan->u.bmu_bitmap &= ~mask; return (nblks); } /* * BLIST_META_FILL() - allocate specific blocks at a meta node * * This routine allocates the specified range of blocks, * regardless of any existing allocations in the range. The * range must be within the extent of this node. Returns the * number of blocks allocated by the call. */ static daddr_t blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count, u_daddr_t radix) { daddr_t blk, i, nblks, next_skip, skip, v; int child; if (scan->bm_bighint == (daddr_t)-1) panic("filling invalid range"); if (count > radix) { /* * The allocation exceeds the number of blocks that are * managed by this node. */ panic("fill too large"); } if (radix == BLIST_BMAP_RADIX) return (blst_leaf_fill(scan, allocBlk, count)); if (count == radix || scan->u.bmu_avail == 0) { /* * ALL-ALLOCATED special case */ nblks = scan->u.bmu_avail; scan->u.bmu_avail = 0; scan->bm_bighint = 0; return (nblks); } skip = radix_to_skip(radix); next_skip = skip / BLIST_META_RADIX; blk = allocBlk & -radix; /* * An ALL-FREE meta node requires special handling before allocating * any of its blocks. */ if (scan->u.bmu_avail == radix) { radix /= BLIST_META_RADIX; /* * Reinitialize each of the meta node's children. An ALL-FREE * meta node cannot have a terminator in any subtree. */ for (i = 1; i < skip; i += next_skip) { if (next_skip == 1) scan[i].u.bmu_bitmap = (u_daddr_t)-1; else scan[i].u.bmu_avail = radix; scan[i].bm_bighint = radix; } } else { radix /= BLIST_META_RADIX; } nblks = 0; child = (allocBlk - blk) / radix; blk += child * radix; i = 1 + child * next_skip; while (i < skip && blk < allocBlk + count) { v = blk + radix - allocBlk; if (v > count) v = count; nblks += blst_meta_fill(&scan[i], allocBlk, v, radix); count -= v; allocBlk += v; blk += radix; i += next_skip; } scan->u.bmu_avail -= nblks; return (nblks); -} - -/* - * BLST_RADIX_INIT() - initialize radix tree - * - * Initialize our meta structures and bitmaps and calculate the exact - * amount of space required to manage 'count' blocks - this space may - * be considerably less than the calculated radix due to the large - * RADIX values we use. - */ -static daddr_t -blst_radix_init(blmeta_t *scan, daddr_t radix, daddr_t count) -{ - daddr_t i, memindex, next_skip, skip; - - memindex = 0; - - /* - * Leaf node - */ - - if (radix == BLIST_BMAP_RADIX) { - if (scan) { - scan->bm_bighint = 0; - scan->u.bmu_bitmap = 0; - } - return (memindex); - } - - /* - * Meta node. If allocating the entire object we can special - * case it. However, we need to figure out how much memory - * is required to manage 'count' blocks, so we continue on anyway. - */ - - if (scan) { - scan->bm_bighint = 0; - scan->u.bmu_avail = 0; - } - - skip = radix_to_skip(radix); - next_skip = skip / BLIST_META_RADIX; - radix /= BLIST_META_RADIX; - - for (i = 1; i < skip; i += next_skip) { - if (count >= radix) { - /* - * Allocate the entire object - */ - memindex = i + - blst_radix_init(((scan) ? &scan[i] : NULL), radix, - radix); - count -= radix; - } else if (count > 0) { - /* - * Allocate a partial object - */ - memindex = i + - blst_radix_init(((scan) ? &scan[i] : NULL), radix, - count); - count = 0; - } else { - /* - * Add terminator and break out. Make terminator bitmap - * zero to avoid a spanning leaf allocation that - * includes the terminator. - */ - if (scan) { - scan[i].bm_bighint = (daddr_t)-1; - scan[i].u.bmu_bitmap = 0; - } - break; - } - } - if (memindex < i) - memindex = i; - return (memindex); } #ifdef BLIST_DEBUG static void blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int tab) { daddr_t i, next_skip, skip; if (radix == BLIST_BMAP_RADIX) { printf( "%*.*s(%08llx,%lld): bitmap %016llx big=%lld\n", tab, tab, "", (long long)blk, (long long)radix, (long long)scan->u.bmu_bitmap, (long long)scan->bm_bighint ); return; } if (scan->u.bmu_avail == 0) { printf( "%*.*s(%08llx,%lld) ALL ALLOCATED\n", tab, tab, "", (long long)blk, (long long)radix ); return; } if (scan->u.bmu_avail == radix) { printf( "%*.*s(%08llx,%lld) ALL FREE\n", tab, tab, "", (long long)blk, (long long)radix ); return; } printf( "%*.*s(%08llx,%lld): subtree (%lld/%lld) big=%lld {\n", tab, tab, "", (long long)blk, (long long)radix, (long long)scan->u.bmu_avail, (long long)radix, (long long)scan->bm_bighint ); skip = radix_to_skip(radix); next_skip = skip / BLIST_META_RADIX; radix /= BLIST_META_RADIX; tab += 4; for (i = 1; i < skip; i += next_skip) { if (scan[i].bm_bighint == (daddr_t)-1) { printf( "%*.*s(%08llx,%lld): Terminator\n", tab, tab, "", (long long)blk, (long long)radix ); break; } blst_radix_print(&scan[i], blk, radix, tab); blk += radix; } tab -= 4; printf( "%*.*s}\n", tab, tab, "" ); } #endif #ifdef BLIST_DEBUG int main(int ac, char **av) { int size = 1024; int i; blist_t bl; struct sbuf *s; for (i = 1; i < ac; ++i) { const char *ptr = av[i]; if (*ptr != '-') { size = strtol(ptr, NULL, 0); continue; } ptr += 2; fprintf(stderr, "Bad option: %s\n", ptr - 2); exit(1); } bl = blist_create(size, M_WAITOK); blist_free(bl, 0, size); for (;;) { char buf[1024]; long long da = 0; long long count = 0; printf("%lld/%lld/%lld> ", (long long)blist_avail(bl), (long long)size, (long long)bl->bl_radix); fflush(stdout); if (fgets(buf, sizeof(buf), stdin) == NULL) break; switch(buf[0]) { case 'r': if (sscanf(buf + 1, "%lld", &count) == 1) { blist_resize(&bl, count, 1, M_WAITOK); } else { printf("?\n"); } case 'p': blist_print(bl); break; case 's': s = sbuf_new_auto(); blist_stats(bl, s); sbuf_finish(s); printf("%s", sbuf_data(s)); sbuf_delete(s); break; case 'a': if (sscanf(buf + 1, "%lld", &count) == 1) { daddr_t blk = blist_alloc(bl, count); printf(" R=%08llx\n", (long long)blk); } else { printf("?\n"); } break; case 'f': if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) { blist_free(bl, da, count); } else { printf("?\n"); } break; case 'l': if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) { printf(" n=%jd\n", (intmax_t)blist_fill(bl, da, count)); } else { printf("?\n"); } break; case '?': case 'h': puts( "p -print\n" "s -stats\n" "a %d -allocate\n" "f %x %d -free\n" "l %x %d -fill\n" "r %d -resize\n" "h/? -help" ); break; default: printf("?\n"); break; } } return(0); } void panic(const char *ctl, ...) { va_list va; va_start(va, ctl); vfprintf(stderr, ctl, va); fprintf(stderr, "\n"); va_end(va); exit(1); } #endif Index: head/sys/sys/blist.h =================================================================== --- head/sys/sys/blist.h (revision 324419) +++ head/sys/sys/blist.h (revision 324420) @@ -1,106 +1,106 @@ /*- * Copyright (c) 1998 Matthew Dillon. 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. * 3. 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 AUTHOR ``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 AUTHOR 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. */ /* * Implements bitmap resource lists. * * Usage: * blist = blist_create(blocks, flags) * (void) blist_destroy(blist) * blkno = blist_alloc(blist, count) * (void) blist_free(blist, blkno, count) * nblks = blist_fill(blist, blkno, count) * (void) blist_resize(&blist, count, freeextra, flags) * * * Notes: * on creation, the entire list is marked reserved. You should * first blist_free() the sections you want to make available * for allocation before doing general blist_alloc()/free() * ops. * * SWAPBLK_NONE is returned on failure. This module is typically * capable of managing up to (2^63) blocks per blist, though * the memory utilization would be insane if you actually did * that. Managing something like 512MB worth of 4K blocks * eats around 32 KBytes of memory. * * $FreeBSD$ */ #ifndef _SYS_BLIST_H_ #define _SYS_BLIST_H_ typedef uint64_t u_daddr_t; /* unsigned disk address */ /* * note: currently use SWAPBLK_NONE as an absolute value rather then * a flag bit. */ #define SWAPBLK_MASK ((daddr_t)((u_daddr_t)-1 >> 1)) /* mask */ #define SWAPBLK_NONE ((daddr_t)((u_daddr_t)SWAPBLK_MASK + 1))/* flag */ /* * Both blmeta and bmu_bitmap MUST be a power of 2 in size. */ typedef struct blmeta { union { daddr_t bmu_avail; /* space available under us */ u_daddr_t bmu_bitmap; /* bitmap if we are a leaf */ } u; daddr_t bm_bighint; /* biggest contiguous block hint*/ } blmeta_t; typedef struct blist { daddr_t bl_blocks; /* area of coverage */ u_daddr_t bl_radix; /* coverage radix */ daddr_t bl_cursor; /* next-fit search starts at */ - blmeta_t *bl_root; /* root of radix tree */ + blmeta_t bl_root[1]; /* root of radix tree */ } *blist_t; #define BLIST_META_RADIX 16 #define BLIST_BMAP_RADIX (sizeof(u_daddr_t)*8) #define BLIST_MAX_ALLOC BLIST_BMAP_RADIX struct sbuf; daddr_t blist_alloc(blist_t blist, daddr_t count); daddr_t blist_avail(blist_t blist); blist_t blist_create(daddr_t blocks, int flags); void blist_destroy(blist_t blist); daddr_t blist_fill(blist_t bl, daddr_t blkno, daddr_t count); void blist_free(blist_t blist, daddr_t blkno, daddr_t count); void blist_print(blist_t blist); void blist_resize(blist_t *pblist, daddr_t count, int freenew, int flags); void blist_stats(blist_t blist, struct sbuf *s); #endif /* _SYS_BLIST_H_ */