/* $OpenBSD: subr_blist.c,v 1.3 2022/08/13 16:02:15 semarie Exp $ */ /* DragonFlyBSD:7b80531f545c7d3c51c1660130c71d01f6bccbe0:/sys/kern/subr_blist.c */ /* * BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting * * Copyright (c) 1998,2004 The DragonFly Project. All rights reserved. * * This code is derived from software contributed to The DragonFly Project * by Matthew Dillon * * 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 DragonFly Project 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 COPYRIGHT HOLDERS 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 * COPYRIGHT HOLDERS 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. * * * 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 is used to maintain the bitmap. Two radix constants are * involved: One for the bitmaps contained in the leaf nodes (typically * 32), and one for the meta nodes (typically 16). Both meta and leaf * nodes have a hint field. This field gives us a hint as to the largest * free contiguous range of blocks under the node. It may contain a * value that is too high, but will never contain a value that is too * low. When the radix tree is searched, allocation failures in subtrees * update the hint. * * 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. * * Unlike the rlist code, the blist code wires all necessary memory at * creation time. Neither allocations nor frees require interaction with * the memory subsystem. In contrast, the rlist code may allocate memory * on an blist_free() call. The non-blocking features of the blist code * are used to great advantage in the swap code (uvm/uvm_swap.c). The * rlist code uses a little less overall memory than the blist code (but * due to swap interleaving not all that much less), but the blist code * scales much, much better. * * LAYOUT: The radix tree is layed out recursively using a * linear array. Each meta node is immediately followed (layed 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 effected by * this algorithmic unfeature. The freeing code can handle arbitrary * ranges. * * NOTE: The radix may exceed BLIST_BMAP_RADIX bits in order to support * up to 2^(BLIST_BMAP_RADIX-1) blocks. The first divison will * drop the radix down and fit it within a signed BLIST_BMAP_RADIX * bit integer. * * This code can be compiled stand-alone for debugging. */ #ifdef _KERNEL #include #include #include #include #else #ifndef BLIST_NO_DEBUG #define BLIST_DEBUG #endif #include #include #include #include #include #include #include #include #define malloc(s,t,f) calloc(1, s) #define mallocarray(n,s,t,f) reallocarray(NULL, n, s) #define free(p,t,s) free(p) #define KASSERT(exp) assert(exp) #define KDASSERT(exp) assert(exp) #include "../sys/blist.h" #define panic(...) do { errx(1, __VA_ARGS__); } while (0) #endif /* * static support functions */ static swblk_t blst_leaf_alloc(blmeta_t *scan, swblk_t blkat, swblk_t blk, swblk_t count); static swblk_t blst_meta_alloc(blmeta_t *scan, swblk_t blkat, swblk_t blk, swblk_t count, swblk_t radix, swblk_t skip); static void blst_leaf_free(blmeta_t *scan, swblk_t relblk, swblk_t count); static void blst_meta_free(blmeta_t *scan, swblk_t freeBlk, swblk_t count, swblk_t radix, swblk_t skip, swblk_t blk); static swblk_t blst_leaf_fill(blmeta_t *scan, swblk_t blk, swblk_t count); static swblk_t blst_meta_fill(blmeta_t *scan, swblk_t fillBlk, swblk_t count, swblk_t radix, swblk_t skip, swblk_t blk); static void blst_copy(blmeta_t *scan, swblk_t blk, swblk_t radix, swblk_t skip, blist_t dest, swblk_t count); static swblk_t blst_radix_init(blmeta_t *scan, swblk_t radix, swblk_t skip, swblk_t count); static int blst_radix_gapfind(blmeta_t *scan, swblk_t blk, swblk_t radix, swblk_t skip, int state, swblk_t *maxbp, swblk_t *maxep, swblk_t *bp, swblk_t *ep); #if defined(BLIST_DEBUG) || defined(DDB) static void blst_radix_print(blmeta_t *scan, swblk_t blk, swblk_t radix, swblk_t skip, int tab); #endif /* * blist_create() - create a blist capable of handling up to the specified * number of blocks * * blocks must be greater than 0 * * The smallest blist consists of a single leaf node capable of * managing BLIST_BMAP_RADIX blocks. * * The pages are addressable in range [0, nblocks[ */ blist_t blist_create(swblk_t blocks) { blist_t bl; swblk_t radix; swblk_t skip = 0; KASSERT(blocks > 0); /* * Calculate radix and skip field used for scanning. * * Radix can exceed BLIST_BMAP_RADIX bits even if swblk_t is limited * to BLIST_BMAP_RADIX bits. * * XXX check overflow */ radix = BLIST_BMAP_RADIX; while (radix < blocks) { radix *= BLIST_META_RADIX; skip = (skip + 1) * BLIST_META_RADIX; KASSERT(skip > 0); } bl = malloc(sizeof(struct blist), M_VMSWAP, M_WAITOK | M_ZERO); bl->bl_blocks = blocks; bl->bl_radix = radix; bl->bl_skip = skip; bl->bl_rootblks = 1 + blst_radix_init(NULL, bl->bl_radix, bl->bl_skip, blocks); bl->bl_root = mallocarray(bl->bl_rootblks, sizeof(blmeta_t), M_VMSWAP, M_WAITOK); #if defined(BLIST_DEBUG) printf( "BLIST representing %lu blocks (%lu MB of swap)" ", requiring %6.2fM of ram\n", bl->bl_blocks, bl->bl_blocks * 4 / 1024, (bl->bl_rootblks * sizeof(blmeta_t) + 1023) / (1024.0 * 1024.0) ); printf("BLIST raw radix tree: %lu records, top-radix %lu\n", bl->bl_rootblks, bl->bl_radix); #endif blst_radix_init(bl->bl_root, bl->bl_radix, bl->bl_skip, blocks); return(bl); } void blist_destroy(blist_t bl) { KASSERT(bl != NULL); free(bl->bl_root, M_VMSWAP, sizeof(blmeta_t) * bl->bl_rootblks); free(bl, M_VMSWAP, sizeof(struct blist)); } /* * blist_alloc() - reserve space in the block bitmap. Return the base * of a contiguous region or SWAPBLK_NONE if space could * not be allocated. */ swblk_t blist_alloc(blist_t bl, swblk_t count) { swblk_t blk = SWAPBLK_NONE; if (bl) { if (bl->bl_radix == BLIST_BMAP_RADIX) blk = blst_leaf_alloc(bl->bl_root, 0, 0, count); else blk = blst_meta_alloc(bl->bl_root, 0, 0, count, bl->bl_radix, bl->bl_skip); if (blk != SWAPBLK_NONE) { bl->bl_free -= count; KDASSERT(blk < bl->bl_blocks); KDASSERT(bl->bl_free <= bl->bl_blocks); } } return(blk); } swblk_t blist_allocat(blist_t bl, swblk_t count, swblk_t blkat) { swblk_t blk = SWAPBLK_NONE; if (bl) { KDASSERT(blkat < bl->bl_blocks); KDASSERT(blkat + count <= bl->bl_blocks); if (bl->bl_radix == BLIST_BMAP_RADIX) blk = blst_leaf_alloc(bl->bl_root, blkat, 0, count); else blk = blst_meta_alloc(bl->bl_root, blkat, 0, count, bl->bl_radix, bl->bl_skip); if (blk != SWAPBLK_NONE) { bl->bl_free -= count; KDASSERT(blk < bl->bl_blocks); KDASSERT(bl->bl_free <= bl->bl_blocks); } } return(blk); } /* * 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, swblk_t blkno, swblk_t count) { if (bl) { KDASSERT(blkno < bl->bl_blocks); KDASSERT(blkno + count <= bl->bl_blocks); if (bl->bl_radix == BLIST_BMAP_RADIX) blst_leaf_free(bl->bl_root, blkno, count); else blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0); bl->bl_free += count; KDASSERT(bl->bl_free <= bl->bl_blocks); } } /* * 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. */ swblk_t blist_fill(blist_t bl, swblk_t blkno, swblk_t count) { swblk_t filled; if (bl) { KDASSERT(blkno < bl->bl_blocks); KDASSERT(blkno + count <= bl->bl_blocks); if (bl->bl_radix == BLIST_BMAP_RADIX) { filled = blst_leaf_fill(bl->bl_root, blkno, count); } else { filled = blst_meta_fill(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0); } bl->bl_free -= filled; KDASSERT(bl->bl_free <= bl->bl_blocks); return (filled); } else { return 0; } } /* * 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, swblk_t count, int freenew) { blist_t newbl = blist_create(count); blist_t save = *pbl; *pbl = newbl; if (count > save->bl_blocks) count = save->bl_blocks; blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, 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); } #define GAPFIND_FIRSTFREE 0 #define GAPFIND_FIRSTUSED 1 /* * blist_gapfind() - return the largest gap (free pages) in blist. * the blist isn't modified. the returned range * is [maxbp, maxep[ . The size of the gap is * maxep - maxbp. If not found, the size is 0. */ void blist_gapfind(blist_t bl, swblk_t *maxbp, swblk_t *maxep) { int state; swblk_t b, e; /* initialize gaps (max and current) */ *maxbp = *maxep = 0; b = e = 0; /* search the larger gap from block 0 */ state = blst_radix_gapfind(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, GAPFIND_FIRSTFREE, maxbp, maxep, &b, &e); if (state == GAPFIND_FIRSTUSED) { e = bl->bl_blocks; if (*maxep - *maxbp < e - b) { *maxbp = b; *maxep = e; } } KDASSERT(*maxbp <= *maxep); KDASSERT(*maxbp < bl->bl_blocks); KDASSERT(*maxep <= bl->bl_blocks); } /* * blst_radix_gapfind - search the larger gap in one pass * * - search first free block, from X -> set B * - search first used block, from B -> set E * - if the size (E - B) is larger than max, update it * - loop (with X=E) until end of blist * - max is the larger free gap */ static int blst_radix_gapfind(blmeta_t *scan, swblk_t blk, swblk_t radix, swblk_t skip, int state, swblk_t *maxbp, swblk_t *maxep, swblk_t *bp, swblk_t *ep) { swblk_t i; swblk_t next_skip; if (radix == BLIST_BMAP_RADIX) { /* leaf node: we considere only completely free bitmap as free */ if (state == GAPFIND_FIRSTFREE) { if (scan->u.bmu_bitmap == (u_swblk_t)-1) { /* node is fully free */ *bp = blk; return GAPFIND_FIRSTUSED; } /* it isn't fully free, not found, keep state */ return state; } else if (state == GAPFIND_FIRSTUSED) { if (scan->u.bmu_bitmap == (u_swblk_t)-1) { /* it is free, not found, keep state */ return state; } /* it is (at least partially) used */ *ep = blk; if (*maxep - *maxbp < *ep - *bp) { *maxbp = *bp; *maxep = *ep; } return GAPFIND_FIRSTFREE; } } if (scan->u.bmu_avail == 0) { /* ALL-ALLOCATED */ if (state == GAPFIND_FIRSTFREE) { /* searching free block, not found, keep state */ return state; } else if (state == GAPFIND_FIRSTUSED) { /* searching used block, found */ *ep = blk; if (*maxep - *maxbp < *ep - *bp) { *maxbp = *bp; *maxep = *ep; } return GAPFIND_FIRSTFREE; } } if (scan->u.bmu_avail == radix) { /* ALL-FREE */ if (state == GAPFIND_FIRSTFREE) { /* searching free block, found */ *bp = blk; return GAPFIND_FIRSTUSED; } else if (state == GAPFIND_FIRSTUSED) { /* searching used block, not found, keep state */ return state; } } radix /= BLIST_META_RADIX; next_skip = (skip / BLIST_META_RADIX); for (i = 1; i <= skip; i += next_skip) { if (scan[i].bm_bighint == (swblk_t)-1) /* Terminator */ break; state = blst_radix_gapfind(&scan[i], blk, radix, next_skip - 1, state, maxbp, maxep, bp, ep); blk += radix; } return state; } #if defined(BLIST_DEBUG) || defined(DDB) /* * blist_print() - dump radix tree */ void blist_print(blist_t bl) { printf("BLIST {\n"); blst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4); printf("}\n"); } #endif /************************************************************************ * 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 1 block * and the BLIST_BMAP_RADIX block allocation cases. Other cases are * somewhat slower. The 1 block allocation case is log2 and extremely * quick. */ static swblk_t blst_leaf_alloc(blmeta_t *scan, swblk_t blkat __unused, swblk_t blk, swblk_t count) { u_swblk_t orig = scan->u.bmu_bitmap; if (orig == 0) { /* * Optimize bitmap all-allocated case. Also, count = 1 * case assumes at least 1 bit is free in the bitmap, so * we have to take care of this case here. */ scan->bm_bighint = 0; return(SWAPBLK_NONE); } if (count == 1) { /* * Optimized code to allocate one bit out of the bitmap */ u_swblk_t mask; int j = BLIST_BMAP_RADIX/2; int r = 0; mask = (u_swblk_t)-1 >> (BLIST_BMAP_RADIX/2); while (j) { if ((orig & mask) == 0) { r += j; orig >>= j; } j >>= 1; mask >>= j; } scan->u.bmu_bitmap &= ~((u_swblk_t)1 << r); return(blk + r); } if (count <= BLIST_BMAP_RADIX) { /* * non-optimized code to allocate N bits out of the bitmap. * The more bits, the faster the code runs. It will run * the slowest allocating 2 bits, but since there aren't any * memory ops in the core loop (or shouldn't be, anyway), * you probably won't notice the difference. */ int j; int n = (int)(BLIST_BMAP_RADIX - count); u_swblk_t mask; mask = (u_swblk_t)-1 >> n; for (j = 0; j <= n; ++j) { if ((orig & mask) == mask) { scan->u.bmu_bitmap &= ~mask; return(blk + j); } mask = (mask << 1); } } /* * We couldn't allocate count in this subtree, update bighint. */ scan->bm_bighint = count - 1; return(SWAPBLK_NONE); } /* * 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 swblk_t blst_meta_alloc(blmeta_t *scan, swblk_t blkat, swblk_t blk, swblk_t count, swblk_t radix, swblk_t skip) { int hintok = (blk >= blkat); swblk_t next_skip = ((swblk_t)skip / BLIST_META_RADIX); swblk_t i; #ifndef _KERNEL printf("blist_meta_alloc blkat %lu blk %lu count %lu radix %lu\n", blkat, blk, count, radix); #endif /* * ALL-ALLOCATED special case */ if (scan->u.bmu_avail == 0) { scan->bm_bighint = 0; return(SWAPBLK_NONE); } /* * ALL-FREE special case, initialize uninitialized * sublevel. * * NOTE: radix may exceed 32 bits until first division. */ if (scan->u.bmu_avail == radix) { scan->bm_bighint = radix; radix /= BLIST_META_RADIX; for (i = 1; i <= skip; i += next_skip) { if (scan[i].bm_bighint == (swblk_t)-1) break; if (next_skip == 1) { scan[i].u.bmu_bitmap = (u_swblk_t)-1; scan[i].bm_bighint = BLIST_BMAP_RADIX; } else { scan[i].bm_bighint = (swblk_t)radix; scan[i].u.bmu_avail = (swblk_t)radix; } } } else { radix /= BLIST_META_RADIX; } for (i = 1; i <= skip; i += next_skip) { if (scan[i].bm_bighint == (swblk_t)-1) { /* * Terminator * * note: check it first, as swblk_t may be unsigned. * otherwise, the second if() might match and the * Terminator will be ignored. */ break; } if (count <= scan[i].bm_bighint && blk + (swblk_t)radix > blkat) { /* * count fits in object */ swblk_t r; if (next_skip == 1) { r = blst_leaf_alloc(&scan[i], blkat, blk, count); } else { r = blst_meta_alloc(&scan[i], blkat, blk, count, radix, next_skip - 1); } if (r != SWAPBLK_NONE) { scan->u.bmu_avail -= count; if (scan->bm_bighint > scan->u.bmu_avail) scan->bm_bighint = scan->u.bmu_avail; return(r); } /* bighint was updated by recursion */ } else if (count > (swblk_t)radix) { /* * count does not fit in object even if it were * complete free. */ panic("%s: allocation too large %lu/%lu", __func__, count, radix); } blk += (swblk_t)radix; } /* * We couldn't allocate count in this subtree, update bighint. */ if (hintok && 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, swblk_t blk, swblk_t count) { /* * free some data in this bitmap * * e.g. * 0000111111111110000 * \_________/\__/ * v n */ int n = blk & (BLIST_BMAP_RADIX - 1); u_swblk_t mask; mask = ((u_swblk_t)-1 << n) & ((u_swblk_t)-1 >> (BLIST_BMAP_RADIX - count - n)); if (scan->u.bmu_bitmap & mask) panic("%s: freeing free block", __func__); 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, swblk_t freeBlk, swblk_t count, swblk_t radix, swblk_t skip, swblk_t blk) { swblk_t i; swblk_t next_skip = ((swblk_t)skip / BLIST_META_RADIX); #if 0 printf("FREE (%04lx,%lu) FROM (%04lx,%lu)\n", freeBlk, count, blk, radix ); #endif /* * ALL-ALLOCATED special case, initialize for recursion. * * We will short-cut the ALL-ALLOCATED -> ALL-FREE case. */ if (scan->u.bmu_avail == 0) { 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 == (swblk_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. * * Set bighint for higher levels to snoop. */ if (scan->u.bmu_avail == radix) { scan->bm_bighint = radix; return; } /* * Break the free down into its components */ if (scan->u.bmu_avail > radix) { panic("%s: freeing already " "free blocks (%lu) %lu/%lu", __func__, count, (long)scan->u.bmu_avail, radix); } radix /= BLIST_META_RADIX; i = (freeBlk - blk) / (swblk_t)radix; blk += i * (swblk_t)radix; i = i * next_skip + 1; while (i <= skip && blk < freeBlk + count) { swblk_t v; v = blk + (swblk_t)radix - freeBlk; if (v > count) v = count; if (scan->bm_bighint == (swblk_t)-1) panic("%s: freeing unexpected range", __func__); if (next_skip == 1) { blst_leaf_free(&scan[i], freeBlk, v); } else { blst_meta_free(&scan[i], freeBlk, v, radix, next_skip - 1, blk); } /* * After having dealt with the becomes-all-free case any * partial free will not be able to bring us to the * becomes-all-free state. * * We can raise bighint to at least the sub-segment's * bighint. */ if (scan->bm_bighint < scan[i].bm_bighint) { scan->bm_bighint = scan[i].bm_bighint; } count -= v; freeBlk += v; blk += (swblk_t)radix; i += next_skip; } } /* * BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap * * 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 swblk_t blst_leaf_fill(blmeta_t *scan, swblk_t blk, swblk_t count) { int n = blk & (BLIST_BMAP_RADIX - 1); swblk_t nblks; u_swblk_t mask, bitmap; mask = ((u_swblk_t)-1 << n) & ((u_swblk_t)-1 >> (BLIST_BMAP_RADIX - count - n)); /* Count the number of blocks we're about to allocate */ bitmap = scan->u.bmu_bitmap & mask; for (nblks = 0; bitmap != 0; nblks++) bitmap &= bitmap - 1; scan->u.bmu_bitmap &= ~mask; return (nblks); } /* * BLST_META_FILL() - allocate specific blocks at a meta node * * 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 swblk_t blst_meta_fill(blmeta_t *scan, swblk_t fillBlk, swblk_t count, swblk_t radix, swblk_t skip, swblk_t blk) { swblk_t i; swblk_t next_skip = ((swblk_t)skip / BLIST_META_RADIX); swblk_t nblks = 0; 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 = count; return (nblks); } if (scan->u.bmu_avail == radix) { radix /= BLIST_META_RADIX; /* * ALL-FREE special case, initialize sublevel */ for (i = 1; i <= skip; i += next_skip) { if (scan[i].bm_bighint == (swblk_t)-1) break; if (next_skip == 1) { scan[i].u.bmu_bitmap = (u_swblk_t)-1; scan[i].bm_bighint = BLIST_BMAP_RADIX; } else { scan[i].bm_bighint = (swblk_t)radix; scan[i].u.bmu_avail = (swblk_t)radix; } } } else { radix /= BLIST_META_RADIX; } if (count > (swblk_t)radix) panic("%s: allocation too large", __func__); i = (fillBlk - blk) / (swblk_t)radix; blk += i * (swblk_t)radix; i = i * next_skip + 1; while (i <= skip && blk < fillBlk + count) { swblk_t v; v = blk + (swblk_t)radix - fillBlk; if (v > count) v = count; if (scan->bm_bighint == (swblk_t)-1) panic("%s: filling unexpected range", __func__); if (next_skip == 1) { nblks += blst_leaf_fill(&scan[i], fillBlk, v); } else { nblks += blst_meta_fill(&scan[i], fillBlk, v, radix, next_skip - 1, blk); } count -= v; fillBlk += v; blk += (swblk_t)radix; i += next_skip; } scan->u.bmu_avail -= nblks; return (nblks); } /* * 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, swblk_t blk, swblk_t radix, swblk_t skip, blist_t dest, swblk_t count) { swblk_t next_skip; swblk_t i; /* * Leaf node */ if (radix == BLIST_BMAP_RADIX) { u_swblk_t v = scan->u.bmu_bitmap; if (v == (u_swblk_t)-1) { blist_free(dest, blk, count); } else if (v != 0) { for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) { if (v & ((swblk_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, (swblk_t)radix); return; } radix /= BLIST_META_RADIX; next_skip = ((u_swblk_t)skip / BLIST_META_RADIX); for (i = 1; count && i <= skip; i += next_skip) { if (scan[i].bm_bighint == (swblk_t)-1) break; if (count >= (swblk_t)radix) { blst_copy( &scan[i], blk, radix, next_skip - 1, dest, (swblk_t)radix ); count -= (swblk_t)radix; } else { if (count) { blst_copy( &scan[i], blk, radix, next_skip - 1, dest, count ); } count = 0; } blk += (swblk_t)radix; } } /* * 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 swblk_t blst_radix_init(blmeta_t *scan, swblk_t radix, swblk_t skip, swblk_t count) { swblk_t i; swblk_t next_skip; swblk_t 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; } radix /= BLIST_META_RADIX; next_skip = ((u_swblk_t)skip / BLIST_META_RADIX); for (i = 1; i <= skip; i += next_skip) { if (count >= (swblk_t)radix) { /* * Allocate the entire object */ memindex = i + blst_radix_init( ((scan) ? &scan[i] : NULL), radix, next_skip - 1, (swblk_t)radix ); count -= (swblk_t)radix; } else if (count > 0) { /* * Allocate a partial object */ memindex = i + blst_radix_init( ((scan) ? &scan[i] : NULL), radix, next_skip - 1, count ); count = 0; } else { /* * Add terminator and break out */ if (scan) scan[i].bm_bighint = (swblk_t)-1; break; } } if (memindex < i) memindex = i; return(memindex); } #if defined(BLIST_DEBUG) || defined(DDB) static void blst_radix_print(blmeta_t *scan, swblk_t blk, swblk_t radix, swblk_t skip, int tab) { swblk_t i; swblk_t next_skip; if (radix == BLIST_BMAP_RADIX) { printf( "%*.*s(%04lx,%lu): bitmap %0*llx big=%lu\n", tab, tab, "", blk, radix, (int)(1 + (BLIST_BMAP_RADIX - 1) / 4), scan->u.bmu_bitmap, scan->bm_bighint ); return; } if (scan->u.bmu_avail == 0) { printf( "%*.*s(%04lx,%lu) ALL ALLOCATED\n", tab, tab, "", blk, radix ); return; } if (scan->u.bmu_avail == radix) { printf( "%*.*s(%04lx,%lu) ALL FREE\n", tab, tab, "", blk, radix ); return; } printf( "%*.*s(%04lx,%lu): subtree (%lu/%lu) big=%lu {\n", tab, tab, "", blk, radix, scan->u.bmu_avail, radix, scan->bm_bighint ); radix /= BLIST_META_RADIX; next_skip = ((u_swblk_t)skip / BLIST_META_RADIX); tab += 4; for (i = 1; i <= skip; i += next_skip) { if (scan[i].bm_bighint == (swblk_t)-1) { printf( "%*.*s(%04lx,%lu): Terminator\n", tab, tab, "", blk, radix ); break; } blst_radix_print( &scan[i], blk, radix, next_skip - 1, tab ); blk += (swblk_t)radix; } tab -= 4; printf( "%*.*s}\n", tab, tab, "" ); } #endif #if !defined(_KERNEL) && defined(BLIST_DEBUG) int main(int ac, char **av) { swblk_t size = 1024; swblk_t i; blist_t bl; for (i = 1; i < (swblk_t)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); blist_free(bl, 0, size); for (;;) { char buf[1024]; swblk_t da = 0; swblk_t count = 0; swblk_t blkat; printf("%lu/%lu/%lu> ", bl->bl_free, size, bl->bl_radix); fflush(stdout); if (fgets(buf, sizeof(buf), stdin) == NULL) break; switch(buf[0]) { case '#': continue; case 'r': if (sscanf(buf + 1, "%li", &count) == 1) { blist_resize(&bl, count, 1); size = count; } else { printf("?\n"); } case 'p': blist_print(bl); break; case 'a': if (sscanf(buf + 1, "%li %li", &count, &blkat) == 1) { printf("count %lu\n", count); swblk_t blk = blist_alloc(bl, count); if (blk == SWAPBLK_NONE) printf(" R=SWAPBLK_NONE\n"); else printf(" R=%04lx\n", blk); } else if (sscanf(buf + 1, "%li %li", &count, &blkat) == 2) { swblk_t blk = blist_allocat(bl, count, blkat); if (blk == SWAPBLK_NONE) printf(" R=SWAPBLK_NONE\n"); else printf(" R=%04lx\n", blk); } else { printf("?\n"); } break; case 'f': if (sscanf(buf + 1, "%li %li", &da, &count) == 2) { blist_free(bl, da, count); } else { printf("?\n"); } break; case 'g': { swblk_t b, e; blist_gapfind(bl, &b, &e); printf("gapfind: begin=%04lx end=%04lx size=%lu\n", b, e, e-b); break; } case 'l': if (sscanf(buf + 1, "%li %li", &da, &count) == 2) { printf(" n=%lu\n", blist_fill(bl, da, count)); } else { printf("?\n"); } break; case '?': case 'h': puts( "p -print\n" "a %li -allocate\n" "f %li %li -free\n" "l %li %li -fill\n" "g -gapfind\n" "r %li -resize\n" "h/? -help\n" " hex may be specified with 0x prefix\n" ); break; default: printf("?\n"); break; } } return(0); } #endif