2 * Copyright (c) 1998 Matthew Dillon. All Rights Reserved.
3 * Redistribution and use in source and binary forms, with or without
4 * modification, are permitted provided that the following conditions
6 * 1. Redistributions of source code must retain the above copyright
7 * notice, this list of conditions and the following disclaimer.
8 * 2. Redistributions in binary form must reproduce the above copyright
9 * notice, this list of conditions and the following disclaimer in the
10 * documentation and/or other materials provided with the distribution.
11 * 4. Neither the name of the University nor the names of its contributors
12 * may be used to endorse or promote products derived from this software
13 * without specific prior written permission.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
21 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
24 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 * BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting
30 * This module implements a general bitmap allocator/deallocator. The
31 * allocator eats around 2 bits per 'block'. The module does not
32 * try to interpret the meaning of a 'block' other than to return
33 * SWAPBLK_NONE on an allocation failure.
35 * A radix tree is used to maintain the bitmap. Two radix constants are
36 * involved: One for the bitmaps contained in the leaf nodes (typically
37 * 32), and one for the meta nodes (typically 16). Both meta and leaf
38 * nodes have a hint field. This field gives us a hint as to the largest
39 * free contiguous range of blocks under the node. It may contain a
40 * value that is too high, but will never contain a value that is too
41 * low. When the radix tree is searched, allocation failures in subtrees
44 * The radix tree also implements two collapsed states for meta nodes:
45 * the ALL-ALLOCATED state and the ALL-FREE state. If a meta node is
46 * in either of these two states, all information contained underneath
47 * the node is considered stale. These states are used to optimize
48 * allocation and freeing operations.
50 * The hinting greatly increases code efficiency for allocations while
51 * the general radix structure optimizes both allocations and frees. The
52 * radix tree should be able to operate well no matter how much
53 * fragmentation there is and no matter how large a bitmap is used.
55 * The blist code wires all necessary memory at creation time. Neither
56 * allocations nor frees require interaction with the memory subsystem.
57 * The non-blocking features of the blist code are used in the swap code
60 * LAYOUT: The radix tree is laid out recursively using a
61 * linear array. Each meta node is immediately followed (laid out
62 * sequentially in memory) by BLIST_META_RADIX lower level nodes. This
63 * is a recursive structure but one that can be easily scanned through
64 * a very simple 'skip' calculation. In order to support large radixes,
65 * portions of the tree may reside outside our memory allocation. We
66 * handle this with an early-termination optimization (when bighint is
67 * set to -1) on the scan. The memory allocation is only large enough
68 * to cover the number of blocks requested at creation time even if it
69 * must be encompassed in larger root-node radix.
71 * NOTE: the allocator cannot currently allocate more than
72 * BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too
73 * large' if you try. This is an area that could use improvement. The
74 * radix is large enough that this restriction does not effect the swap
75 * system, though. Currently only the allocation code is effected by
76 * this algorithmic unfeature. The freeing code can handle arbitrary
79 * This code can be compiled stand-alone for debugging.
82 #include <sys/cdefs.h>
83 __FBSDID("$FreeBSD$");
87 #include <sys/param.h>
88 #include <sys/systm.h>
90 #include <sys/kernel.h>
91 #include <sys/blist.h>
92 #include <sys/malloc.h>
94 #include <sys/mutex.h>
98 #ifndef BLIST_NO_DEBUG
102 #include <sys/types.h>
103 #include <sys/malloc.h>
109 #define bitcount64(x) __bitcount64((uint64_t)(x))
110 #define malloc(a,b,c) calloc(a, 1)
111 #define free(a,b) free(a)
113 #include <sys/blist.h>
115 void panic(const char *ctl, ...);
120 * static support functions
123 static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count);
124 static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk,
125 daddr_t count, daddr_t radix, int skip);
126 static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count);
127 static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count,
128 daddr_t radix, int skip, daddr_t blk);
129 static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix,
130 daddr_t skip, blist_t dest, daddr_t count);
131 static daddr_t blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count);
132 static daddr_t blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count,
133 daddr_t radix, int skip, daddr_t blk);
134 static daddr_t blst_radix_init(blmeta_t *scan, daddr_t radix,
135 int skip, daddr_t count);
137 static void blst_radix_print(blmeta_t *scan, daddr_t blk,
138 daddr_t radix, int skip, int tab);
142 static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
146 * blist_create() - create a blist capable of handling up to the specified
149 * blocks - must be greater than 0
150 * flags - malloc flags
152 * The smallest blist consists of a single leaf node capable of
153 * managing BLIST_BMAP_RADIX blocks.
157 blist_create(daddr_t blocks, int flags)
160 daddr_t nodes, radix;
164 * Calculate radix and skip field used for scanning.
166 radix = BLIST_BMAP_RADIX;
168 while (radix < blocks) {
169 radix *= BLIST_META_RADIX;
170 skip = (skip + 1) * BLIST_META_RADIX;
173 bl = malloc(sizeof(struct blist), M_SWAP, flags);
177 bl->bl_blocks = blocks;
178 bl->bl_radix = radix;
180 nodes = 1 + blst_radix_init(NULL, radix, bl->bl_skip, blocks);
181 bl->bl_root = malloc(nodes * sizeof(blmeta_t), M_SWAP, flags);
182 if (bl->bl_root == NULL) {
186 blst_radix_init(bl->bl_root, radix, bl->bl_skip, blocks);
188 #if defined(BLIST_DEBUG)
190 "BLIST representing %lld blocks (%lld MB of swap)"
191 ", requiring %lldK of ram\n",
192 (long long)bl->bl_blocks,
193 (long long)bl->bl_blocks * 4 / 1024,
194 (long long)(nodes * sizeof(blmeta_t) + 1023) / 1024
196 printf("BLIST raw radix tree contains %lld records\n",
204 blist_destroy(blist_t bl)
206 free(bl->bl_root, M_SWAP);
211 * blist_alloc() - reserve space in the block bitmap. Return the base
212 * of a contiguous region or SWAPBLK_NONE if space could
217 blist_alloc(blist_t bl, daddr_t count)
221 if (bl != NULL && count <= bl->bl_root->bm_bighint) {
222 if (bl->bl_radix == BLIST_BMAP_RADIX)
223 blk = blst_leaf_alloc(bl->bl_root, 0, count);
225 blk = blst_meta_alloc(bl->bl_root, 0, count,
226 bl->bl_radix, bl->bl_skip);
229 return (SWAPBLK_NONE);
233 * blist_avail() - return the number of free blocks.
237 blist_avail(blist_t bl)
240 if (bl->bl_radix == BLIST_BMAP_RADIX)
241 return (bitcount64(bl->bl_root->u.bmu_bitmap));
243 return (bl->bl_root->u.bmu_avail);
247 * blist_free() - free up space in the block bitmap. Return the base
248 * of a contiguous region. Panic if an inconsistancy is
253 blist_free(blist_t bl, daddr_t blkno, daddr_t count)
256 if (bl->bl_radix == BLIST_BMAP_RADIX)
257 blst_leaf_free(bl->bl_root, blkno, count);
259 blst_meta_free(bl->bl_root, blkno, count,
260 bl->bl_radix, bl->bl_skip, 0);
265 * blist_fill() - mark a region in the block bitmap as off-limits
266 * to the allocator (i.e. allocate it), ignoring any
267 * existing allocations. Return the number of blocks
268 * actually filled that were free before the call.
272 blist_fill(blist_t bl, daddr_t blkno, daddr_t count)
277 if (bl->bl_radix == BLIST_BMAP_RADIX)
278 filled = blst_leaf_fill(bl->bl_root, blkno, count);
280 filled = blst_meta_fill(bl->bl_root, blkno, count,
281 bl->bl_radix, bl->bl_skip, 0);
288 * blist_resize() - resize an existing radix tree to handle the
289 * specified number of blocks. This will reallocate
290 * the tree and transfer the previous bitmap to the new
291 * one. When extending the tree you can specify whether
292 * the new blocks are to left allocated or freed.
296 blist_resize(blist_t *pbl, daddr_t count, int freenew, int flags)
298 blist_t newbl = blist_create(count, flags);
302 if (count > save->bl_blocks)
303 count = save->bl_blocks;
304 blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, newbl, count);
307 * If resizing upwards, should we free the new space or not?
309 if (freenew && count < newbl->bl_blocks) {
310 blist_free(newbl, count, newbl->bl_blocks - count);
318 * blist_print() - dump radix tree
322 blist_print(blist_t bl)
325 blst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4);
331 /************************************************************************
332 * ALLOCATION SUPPORT FUNCTIONS *
333 ************************************************************************
335 * These support functions do all the actual work. They may seem
336 * rather longish, but that's because I've commented them up. The
337 * actual code is straight forward.
342 * blist_leaf_alloc() - allocate at a leaf in the radix tree (a bitmap).
344 * This is the core of the allocator and is optimized for the 1 block
345 * and the BLIST_BMAP_RADIX block allocation cases. Other cases are
346 * somewhat slower. The 1 block allocation case is log2 and extremely
356 u_daddr_t orig = scan->u.bmu_bitmap;
360 * Optimize bitmap all-allocated case. Also, count = 1
361 * case assumes at least 1 bit is free in the bitmap, so
362 * we have to take care of this case here.
364 scan->bm_bighint = 0;
365 return(SWAPBLK_NONE);
369 * Optimized code to allocate one bit out of the bitmap
372 int j = BLIST_BMAP_RADIX/2;
375 mask = (u_daddr_t)-1 >> (BLIST_BMAP_RADIX/2);
378 if ((orig & mask) == 0) {
385 scan->u.bmu_bitmap &= ~((u_daddr_t)1 << r);
388 if (count <= BLIST_BMAP_RADIX) {
390 * non-optimized code to allocate N bits out of the bitmap.
391 * The more bits, the faster the code runs. It will run
392 * the slowest allocating 2 bits, but since there aren't any
393 * memory ops in the core loop (or shouldn't be, anyway),
394 * you probably won't notice the difference.
397 int n = BLIST_BMAP_RADIX - count;
400 mask = (u_daddr_t)-1 >> n;
402 for (j = 0; j <= n; ++j) {
403 if ((orig & mask) == mask) {
404 scan->u.bmu_bitmap &= ~mask;
411 * We couldn't allocate count in this subtree, update bighint.
413 scan->bm_bighint = count - 1;
414 return(SWAPBLK_NONE);
418 * blist_meta_alloc() - allocate at a meta in the radix tree.
420 * Attempt to allocate at a meta node. If we can't, we update
421 * bighint and return a failure. Updating bighint optimize future
422 * calls that hit this node. We have to check for our collapse cases
423 * and we have a few optimizations strewn in as well.
436 int next_skip = ((u_int)skip / BLIST_META_RADIX);
438 if (scan->u.bmu_avail < count) {
440 * The meta node's hint must be too large if the allocation
441 * exceeds the number of free blocks. Reduce the hint, and
444 scan->bm_bighint = scan->u.bmu_avail;
445 return (SWAPBLK_NONE);
449 * An ALL-FREE meta node requires special handling before allocating
452 if (scan->u.bmu_avail == radix) {
453 radix /= BLIST_META_RADIX;
456 * Reinitialize each of the meta node's children. An ALL-FREE
457 * meta node cannot have a terminator in any subtree.
459 for (i = 1; i <= skip; i += next_skip) {
460 if (next_skip == 1) {
461 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
462 scan[i].bm_bighint = BLIST_BMAP_RADIX;
464 scan[i].bm_bighint = radix;
465 scan[i].u.bmu_avail = radix;
469 radix /= BLIST_META_RADIX;
474 * The allocation exceeds the number of blocks that are
475 * managed by a subtree of this meta node.
477 panic("allocation too large");
479 for (i = 1; i <= skip; i += next_skip) {
480 if (count <= scan[i].bm_bighint) {
482 * The allocation might fit in the i'th subtree.
484 if (next_skip == 1) {
485 r = blst_leaf_alloc(&scan[i], blk, count);
487 r = blst_meta_alloc(&scan[i], blk, count,
488 radix, next_skip - 1);
490 if (r != SWAPBLK_NONE) {
491 scan->u.bmu_avail -= count;
494 } else if (scan[i].bm_bighint == (daddr_t)-1) {
504 * We couldn't allocate count in this subtree, update bighint.
506 if (scan->bm_bighint >= count)
507 scan->bm_bighint = count - 1;
508 return(SWAPBLK_NONE);
512 * BLST_LEAF_FREE() - free allocated block from leaf bitmap
523 * free some data in this bitmap
526 * 0000111111111110000
530 int n = blk & (BLIST_BMAP_RADIX - 1);
533 mask = ((u_daddr_t)-1 << n) &
534 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
536 if (scan->u.bmu_bitmap & mask)
537 panic("blst_radix_free: freeing free block");
538 scan->u.bmu_bitmap |= mask;
541 * We could probably do a better job here. We are required to make
542 * bighint at least as large as the biggest contiguous block of
543 * data. If we just shoehorn it, a little extra overhead will
544 * be incured on the next allocation (but only that one typically).
546 scan->bm_bighint = BLIST_BMAP_RADIX;
550 * BLST_META_FREE() - free allocated blocks from radix tree meta info
552 * This support routine frees a range of blocks from the bitmap.
553 * The range must be entirely enclosed by this radix node. If a
554 * meta node, we break the range down recursively to free blocks
555 * in subnodes (which means that this code can free an arbitrary
556 * range whereas the allocation code cannot allocate an arbitrary
570 int next_skip = ((u_int)skip / BLIST_META_RADIX);
573 printf("free (%llx,%lld) FROM (%llx,%lld)\n",
574 (long long)freeBlk, (long long)count,
575 (long long)blk, (long long)radix
579 if (scan->u.bmu_avail == 0) {
581 * ALL-ALLOCATED special case, with possible
582 * shortcut to ALL-FREE special case.
584 scan->u.bmu_avail = count;
585 scan->bm_bighint = count;
587 if (count != radix) {
588 for (i = 1; i <= skip; i += next_skip) {
589 if (scan[i].bm_bighint == (daddr_t)-1)
591 scan[i].bm_bighint = 0;
592 if (next_skip == 1) {
593 scan[i].u.bmu_bitmap = 0;
595 scan[i].u.bmu_avail = 0;
601 scan->u.bmu_avail += count;
602 /* scan->bm_bighint = radix; */
606 * ALL-FREE special case.
609 if (scan->u.bmu_avail == radix)
611 if (scan->u.bmu_avail > radix)
612 panic("blst_meta_free: freeing already free blocks (%lld) %lld/%lld",
613 (long long)count, (long long)scan->u.bmu_avail,
617 * Break the free down into its components
620 radix /= BLIST_META_RADIX;
622 i = (freeBlk - blk) / radix;
624 i = i * next_skip + 1;
626 while (i <= skip && blk < freeBlk + count) {
629 v = blk + radix - freeBlk;
633 if (scan->bm_bighint == (daddr_t)-1)
634 panic("blst_meta_free: freeing unexpected range");
636 if (next_skip == 1) {
637 blst_leaf_free(&scan[i], freeBlk, v);
639 blst_meta_free(&scan[i], freeBlk, v, radix, next_skip - 1, blk);
641 if (scan->bm_bighint < scan[i].bm_bighint)
642 scan->bm_bighint = scan[i].bm_bighint;
651 * BLIST_RADIX_COPY() - copy one radix tree to another
653 * Locates free space in the source tree and frees it in the destination
654 * tree. The space may not already be free in the destination.
657 static void blst_copy(
672 if (radix == BLIST_BMAP_RADIX) {
673 u_daddr_t v = scan->u.bmu_bitmap;
675 if (v == (u_daddr_t)-1) {
676 blist_free(dest, blk, count);
680 for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) {
681 if (v & ((u_daddr_t)1 << i))
682 blist_free(dest, blk + i, 1);
692 if (scan->u.bmu_avail == 0) {
694 * Source all allocated, leave dest allocated
698 if (scan->u.bmu_avail == radix) {
700 * Source all free, free entire dest
703 blist_free(dest, blk, count);
705 blist_free(dest, blk, radix);
710 radix /= BLIST_META_RADIX;
711 next_skip = ((u_int)skip / BLIST_META_RADIX);
713 for (i = 1; count && i <= skip; i += next_skip) {
714 if (scan[i].bm_bighint == (daddr_t)-1)
717 if (count >= radix) {
745 * BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap
747 * This routine allocates all blocks in the specified range
748 * regardless of any existing allocations in that range. Returns
749 * the number of blocks allocated by the call.
753 blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count)
755 int n = blk & (BLIST_BMAP_RADIX - 1);
759 mask = ((u_daddr_t)-1 << n) &
760 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
762 /* Count the number of blocks that we are allocating. */
763 nblks = bitcount64(scan->u.bmu_bitmap & mask);
765 scan->u.bmu_bitmap &= ~mask;
770 * BLIST_META_FILL() - allocate specific blocks at a meta node
772 * This routine allocates the specified range of blocks,
773 * regardless of any existing allocations in the range. The
774 * range must be within the extent of this node. Returns the
775 * number of blocks allocated by the call.
787 int next_skip = ((u_int)skip / BLIST_META_RADIX);
792 * The allocation exceeds the number of blocks that are
793 * managed by this meta node.
795 panic("allocation too large");
797 if (count == radix || scan->u.bmu_avail == 0) {
799 * ALL-ALLOCATED special case
801 nblks = scan->u.bmu_avail;
802 scan->u.bmu_avail = 0;
803 scan->bm_bighint = 0;
808 * An ALL-FREE meta node requires special handling before allocating
811 if (scan->u.bmu_avail == radix) {
812 radix /= BLIST_META_RADIX;
815 * Reinitialize each of the meta node's children. An ALL-FREE
816 * meta node cannot have a terminator in any subtree.
818 for (i = 1; i <= skip; i += next_skip) {
819 if (next_skip == 1) {
820 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
821 scan[i].bm_bighint = BLIST_BMAP_RADIX;
823 scan[i].bm_bighint = radix;
824 scan[i].u.bmu_avail = radix;
828 radix /= BLIST_META_RADIX;
831 i = (allocBlk - blk) / radix;
833 i = i * next_skip + 1;
835 while (i <= skip && blk < allocBlk + count) {
838 v = blk + radix - allocBlk;
842 if (scan->bm_bighint == (daddr_t)-1)
843 panic("blst_meta_fill: filling unexpected range");
845 if (next_skip == 1) {
846 nblks += blst_leaf_fill(&scan[i], allocBlk, v);
848 nblks += blst_meta_fill(&scan[i], allocBlk, v,
849 radix, next_skip - 1, blk);
856 scan->u.bmu_avail -= nblks;
861 * BLST_RADIX_INIT() - initialize radix tree
863 * Initialize our meta structures and bitmaps and calculate the exact
864 * amount of space required to manage 'count' blocks - this space may
865 * be considerably less than the calculated radix due to the large
866 * RADIX values we use.
870 blst_radix_init(blmeta_t *scan, daddr_t radix, int skip, daddr_t count)
874 daddr_t memindex = 0;
880 if (radix == BLIST_BMAP_RADIX) {
882 scan->bm_bighint = 0;
883 scan->u.bmu_bitmap = 0;
889 * Meta node. If allocating the entire object we can special
890 * case it. However, we need to figure out how much memory
891 * is required to manage 'count' blocks, so we continue on anyway.
895 scan->bm_bighint = 0;
896 scan->u.bmu_avail = 0;
899 radix /= BLIST_META_RADIX;
900 next_skip = ((u_int)skip / BLIST_META_RADIX);
902 for (i = 1; i <= skip; i += next_skip) {
903 if (count >= radix) {
905 * Allocate the entire object
907 memindex = i + blst_radix_init(
908 ((scan) ? &scan[i] : NULL),
914 } else if (count > 0) {
916 * Allocate a partial object
918 memindex = i + blst_radix_init(
919 ((scan) ? &scan[i] : NULL),
927 * Add terminator and break out
930 scan[i].bm_bighint = (daddr_t)-1;
942 blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int skip, int tab)
948 if (radix == BLIST_BMAP_RADIX) {
950 "%*.*s(%08llx,%lld): bitmap %016llx big=%lld\n",
952 (long long)blk, (long long)radix,
953 (long long)scan->u.bmu_bitmap,
954 (long long)scan->bm_bighint
959 if (scan->u.bmu_avail == 0) {
961 "%*.*s(%08llx,%lld) ALL ALLOCATED\n",
968 if (scan->u.bmu_avail == radix) {
970 "%*.*s(%08llx,%lld) ALL FREE\n",
979 "%*.*s(%08llx,%lld): subtree (%lld/%lld) big=%lld {\n",
981 (long long)blk, (long long)radix,
982 (long long)scan->u.bmu_avail,
984 (long long)scan->bm_bighint
987 radix /= BLIST_META_RADIX;
988 next_skip = ((u_int)skip / BLIST_META_RADIX);
991 for (i = 1; i <= skip; i += next_skip) {
992 if (scan[i].bm_bighint == (daddr_t)-1) {
994 "%*.*s(%08llx,%lld): Terminator\n",
996 (long long)blk, (long long)radix
1023 main(int ac, char **av)
1029 for (i = 1; i < ac; ++i) {
1030 const char *ptr = av[i];
1032 size = strtol(ptr, NULL, 0);
1036 fprintf(stderr, "Bad option: %s\n", ptr - 2);
1039 bl = blist_create(size, M_WAITOK);
1040 blist_free(bl, 0, size);
1045 long long count = 0;
1047 printf("%lld/%lld/%lld> ", (long long)blist_avail(bl),
1048 (long long)size, (long long)bl->bl_radix);
1050 if (fgets(buf, sizeof(buf), stdin) == NULL)
1054 if (sscanf(buf + 1, "%lld", &count) == 1) {
1055 blist_resize(&bl, count, 1, M_WAITOK);
1063 if (sscanf(buf + 1, "%lld", &count) == 1) {
1064 daddr_t blk = blist_alloc(bl, count);
1065 printf(" R=%08llx\n", (long long)blk);
1071 if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) {
1072 blist_free(bl, da, count);
1078 if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) {
1080 (intmax_t)blist_fill(bl, da, count));
1105 panic(const char *ctl, ...)
1110 vfprintf(stderr, ctl, va);
1111 fprintf(stderr, "\n");