FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_blist.c
1 /*-
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
5 * are met:
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.
14 *
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.
26 */
27 /*
28 * BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting
29 *
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.
34 *
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
42 * update the hint.
43 *
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.
49 *
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.
54 *
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
58 * (vm/swap_pager.c).
59 *
60 * LAYOUT: The radix tree is layed out recursively using a
61 * linear array. Each meta node is immediately followed (layed 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.
70 *
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
77 * ranges.
78 *
79 * This code can be compiled stand-alone for debugging.
80 */
81
82 #include <sys/cdefs.h>
83 __FBSDID("$FreeBSD: releng/10.2/sys/kern/subr_blist.c 246370 2013-02-05 20:08:33Z pluknet $");
84
85 #ifdef _KERNEL
86
87 #include <sys/param.h>
88 #include <sys/systm.h>
89 #include <sys/lock.h>
90 #include <sys/kernel.h>
91 #include <sys/blist.h>
92 #include <sys/malloc.h>
93 #include <sys/proc.h>
94 #include <sys/mutex.h>
95
96 #else
97
98 #ifndef BLIST_NO_DEBUG
99 #define BLIST_DEBUG
100 #endif
101
102 #define SWAPBLK_NONE ((daddr_t)-1)
103
104 #include <sys/types.h>
105 #include <stdio.h>
106 #include <string.h>
107 #include <stdlib.h>
108 #include <stdarg.h>
109
110 #define malloc(a,b,c) calloc(a, 1)
111 #define free(a,b) free(a)
112
113 typedef unsigned int u_daddr_t;
114
115 #include <sys/blist.h>
116
117 void panic(const char *ctl, ...);
118
119 #endif
120
121 /*
122 * static support functions
123 */
124
125 static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count);
126 static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk,
127 daddr_t count, daddr_t radix, int skip);
128 static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count);
129 static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count,
130 daddr_t radix, int skip, daddr_t blk);
131 static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix,
132 daddr_t skip, blist_t dest, daddr_t count);
133 static int blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count);
134 static int blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count,
135 daddr_t radix, int skip, daddr_t blk);
136 static daddr_t blst_radix_init(blmeta_t *scan, daddr_t radix,
137 int skip, daddr_t count);
138 #ifndef _KERNEL
139 static void blst_radix_print(blmeta_t *scan, daddr_t blk,
140 daddr_t radix, int skip, int tab);
141 #endif
142
143 #ifdef _KERNEL
144 static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
145 #endif
146
147 /*
148 * blist_create() - create a blist capable of handling up to the specified
149 * number of blocks
150 *
151 * blocks - must be greater than 0
152 * flags - malloc flags
153 *
154 * The smallest blist consists of a single leaf node capable of
155 * managing BLIST_BMAP_RADIX blocks.
156 */
157
158 blist_t
159 blist_create(daddr_t blocks, int flags)
160 {
161 blist_t bl;
162 int radix;
163 int skip = 0;
164
165 /*
166 * Calculate radix and skip field used for scanning.
167 */
168 radix = BLIST_BMAP_RADIX;
169
170 while (radix < blocks) {
171 radix *= BLIST_META_RADIX;
172 skip = (skip + 1) * BLIST_META_RADIX;
173 }
174
175 bl = malloc(sizeof(struct blist), M_SWAP, flags | M_ZERO);
176
177 bl->bl_blocks = blocks;
178 bl->bl_radix = radix;
179 bl->bl_skip = skip;
180 bl->bl_rootblks = 1 +
181 blst_radix_init(NULL, bl->bl_radix, bl->bl_skip, blocks);
182 bl->bl_root = malloc(sizeof(blmeta_t) * bl->bl_rootblks, M_SWAP, flags);
183
184 #if defined(BLIST_DEBUG)
185 printf(
186 "BLIST representing %lld blocks (%lld MB of swap)"
187 ", requiring %lldK of ram\n",
188 (long long)bl->bl_blocks,
189 (long long)bl->bl_blocks * 4 / 1024,
190 (long long)(bl->bl_rootblks * sizeof(blmeta_t) + 1023) / 1024
191 );
192 printf("BLIST raw radix tree contains %lld records\n",
193 (long long)bl->bl_rootblks);
194 #endif
195 blst_radix_init(bl->bl_root, bl->bl_radix, bl->bl_skip, blocks);
196
197 return(bl);
198 }
199
200 void
201 blist_destroy(blist_t bl)
202 {
203 free(bl->bl_root, M_SWAP);
204 free(bl, M_SWAP);
205 }
206
207 /*
208 * blist_alloc() - reserve space in the block bitmap. Return the base
209 * of a contiguous region or SWAPBLK_NONE if space could
210 * not be allocated.
211 */
212
213 daddr_t
214 blist_alloc(blist_t bl, daddr_t count)
215 {
216 daddr_t blk = SWAPBLK_NONE;
217
218 if (bl) {
219 if (bl->bl_radix == BLIST_BMAP_RADIX)
220 blk = blst_leaf_alloc(bl->bl_root, 0, count);
221 else
222 blk = blst_meta_alloc(bl->bl_root, 0, count, bl->bl_radix, bl->bl_skip);
223 if (blk != SWAPBLK_NONE)
224 bl->bl_free -= count;
225 }
226 return(blk);
227 }
228
229 /*
230 * blist_free() - free up space in the block bitmap. Return the base
231 * of a contiguous region. Panic if an inconsistancy is
232 * found.
233 */
234
235 void
236 blist_free(blist_t bl, daddr_t blkno, daddr_t count)
237 {
238 if (bl) {
239 if (bl->bl_radix == BLIST_BMAP_RADIX)
240 blst_leaf_free(bl->bl_root, blkno, count);
241 else
242 blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0);
243 bl->bl_free += count;
244 }
245 }
246
247 /*
248 * blist_fill() - mark a region in the block bitmap as off-limits
249 * to the allocator (i.e. allocate it), ignoring any
250 * existing allocations. Return the number of blocks
251 * actually filled that were free before the call.
252 */
253
254 int
255 blist_fill(blist_t bl, daddr_t blkno, daddr_t count)
256 {
257 int filled;
258
259 if (bl) {
260 if (bl->bl_radix == BLIST_BMAP_RADIX)
261 filled = blst_leaf_fill(bl->bl_root, blkno, count);
262 else
263 filled = blst_meta_fill(bl->bl_root, blkno, count,
264 bl->bl_radix, bl->bl_skip, 0);
265 bl->bl_free -= filled;
266 return filled;
267 } else
268 return 0;
269 }
270
271 /*
272 * blist_resize() - resize an existing radix tree to handle the
273 * specified number of blocks. This will reallocate
274 * the tree and transfer the previous bitmap to the new
275 * one. When extending the tree you can specify whether
276 * the new blocks are to left allocated or freed.
277 */
278
279 void
280 blist_resize(blist_t *pbl, daddr_t count, int freenew, int flags)
281 {
282 blist_t newbl = blist_create(count, flags);
283 blist_t save = *pbl;
284
285 *pbl = newbl;
286 if (count > save->bl_blocks)
287 count = save->bl_blocks;
288 blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, newbl, count);
289
290 /*
291 * If resizing upwards, should we free the new space or not?
292 */
293 if (freenew && count < newbl->bl_blocks) {
294 blist_free(newbl, count, newbl->bl_blocks - count);
295 }
296 blist_destroy(save);
297 }
298
299 #ifdef BLIST_DEBUG
300
301 /*
302 * blist_print() - dump radix tree
303 */
304
305 void
306 blist_print(blist_t bl)
307 {
308 printf("BLIST {\n");
309 blst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4);
310 printf("}\n");
311 }
312
313 #endif
314
315 /************************************************************************
316 * ALLOCATION SUPPORT FUNCTIONS *
317 ************************************************************************
318 *
319 * These support functions do all the actual work. They may seem
320 * rather longish, but that's because I've commented them up. The
321 * actual code is straight forward.
322 *
323 */
324
325 /*
326 * blist_leaf_alloc() - allocate at a leaf in the radix tree (a bitmap).
327 *
328 * This is the core of the allocator and is optimized for the 1 block
329 * and the BLIST_BMAP_RADIX block allocation cases. Other cases are
330 * somewhat slower. The 1 block allocation case is log2 and extremely
331 * quick.
332 */
333
334 static daddr_t
335 blst_leaf_alloc(
336 blmeta_t *scan,
337 daddr_t blk,
338 int count
339 ) {
340 u_daddr_t orig = scan->u.bmu_bitmap;
341
342 if (orig == 0) {
343 /*
344 * Optimize bitmap all-allocated case. Also, count = 1
345 * case assumes at least 1 bit is free in the bitmap, so
346 * we have to take care of this case here.
347 */
348 scan->bm_bighint = 0;
349 return(SWAPBLK_NONE);
350 }
351 if (count == 1) {
352 /*
353 * Optimized code to allocate one bit out of the bitmap
354 */
355 u_daddr_t mask;
356 int j = BLIST_BMAP_RADIX/2;
357 int r = 0;
358
359 mask = (u_daddr_t)-1 >> (BLIST_BMAP_RADIX/2);
360
361 while (j) {
362 if ((orig & mask) == 0) {
363 r += j;
364 orig >>= j;
365 }
366 j >>= 1;
367 mask >>= j;
368 }
369 scan->u.bmu_bitmap &= ~(1 << r);
370 return(blk + r);
371 }
372 if (count <= BLIST_BMAP_RADIX) {
373 /*
374 * non-optimized code to allocate N bits out of the bitmap.
375 * The more bits, the faster the code runs. It will run
376 * the slowest allocating 2 bits, but since there aren't any
377 * memory ops in the core loop (or shouldn't be, anyway),
378 * you probably won't notice the difference.
379 */
380 int j;
381 int n = BLIST_BMAP_RADIX - count;
382 u_daddr_t mask;
383
384 mask = (u_daddr_t)-1 >> n;
385
386 for (j = 0; j <= n; ++j) {
387 if ((orig & mask) == mask) {
388 scan->u.bmu_bitmap &= ~mask;
389 return(blk + j);
390 }
391 mask = (mask << 1);
392 }
393 }
394 /*
395 * We couldn't allocate count in this subtree, update bighint.
396 */
397 scan->bm_bighint = count - 1;
398 return(SWAPBLK_NONE);
399 }
400
401 /*
402 * blist_meta_alloc() - allocate at a meta in the radix tree.
403 *
404 * Attempt to allocate at a meta node. If we can't, we update
405 * bighint and return a failure. Updating bighint optimize future
406 * calls that hit this node. We have to check for our collapse cases
407 * and we have a few optimizations strewn in as well.
408 */
409
410 static daddr_t
411 blst_meta_alloc(
412 blmeta_t *scan,
413 daddr_t blk,
414 daddr_t count,
415 daddr_t radix,
416 int skip
417 ) {
418 int i;
419 int next_skip = ((u_int)skip / BLIST_META_RADIX);
420
421 if (scan->u.bmu_avail == 0) {
422 /*
423 * ALL-ALLOCATED special case
424 */
425 scan->bm_bighint = count;
426 return(SWAPBLK_NONE);
427 }
428
429 if (scan->u.bmu_avail == radix) {
430 radix /= BLIST_META_RADIX;
431
432 /*
433 * ALL-FREE special case, initialize uninitialize
434 * sublevel.
435 */
436 for (i = 1; i <= skip; i += next_skip) {
437 if (scan[i].bm_bighint == (daddr_t)-1)
438 break;
439 if (next_skip == 1) {
440 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
441 scan[i].bm_bighint = BLIST_BMAP_RADIX;
442 } else {
443 scan[i].bm_bighint = radix;
444 scan[i].u.bmu_avail = radix;
445 }
446 }
447 } else {
448 radix /= BLIST_META_RADIX;
449 }
450
451 for (i = 1; i <= skip; i += next_skip) {
452 if (count <= scan[i].bm_bighint) {
453 /*
454 * count fits in object
455 */
456 daddr_t r;
457 if (next_skip == 1) {
458 r = blst_leaf_alloc(&scan[i], blk, count);
459 } else {
460 r = blst_meta_alloc(&scan[i], blk, count, radix, next_skip - 1);
461 }
462 if (r != SWAPBLK_NONE) {
463 scan->u.bmu_avail -= count;
464 if (scan->bm_bighint > scan->u.bmu_avail)
465 scan->bm_bighint = scan->u.bmu_avail;
466 return(r);
467 }
468 } else if (scan[i].bm_bighint == (daddr_t)-1) {
469 /*
470 * Terminator
471 */
472 break;
473 } else if (count > radix) {
474 /*
475 * count does not fit in object even if it were
476 * complete free.
477 */
478 panic("blist_meta_alloc: allocation too large");
479 }
480 blk += radix;
481 }
482
483 /*
484 * We couldn't allocate count in this subtree, update bighint.
485 */
486 if (scan->bm_bighint >= count)
487 scan->bm_bighint = count - 1;
488 return(SWAPBLK_NONE);
489 }
490
491 /*
492 * BLST_LEAF_FREE() - free allocated block from leaf bitmap
493 *
494 */
495
496 static void
497 blst_leaf_free(
498 blmeta_t *scan,
499 daddr_t blk,
500 int count
501 ) {
502 /*
503 * free some data in this bitmap
504 *
505 * e.g.
506 * 0000111111111110000
507 * \_________/\__/
508 * v n
509 */
510 int n = blk & (BLIST_BMAP_RADIX - 1);
511 u_daddr_t mask;
512
513 mask = ((u_daddr_t)-1 << n) &
514 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
515
516 if (scan->u.bmu_bitmap & mask)
517 panic("blst_radix_free: freeing free block");
518 scan->u.bmu_bitmap |= mask;
519
520 /*
521 * We could probably do a better job here. We are required to make
522 * bighint at least as large as the biggest contiguous block of
523 * data. If we just shoehorn it, a little extra overhead will
524 * be incured on the next allocation (but only that one typically).
525 */
526 scan->bm_bighint = BLIST_BMAP_RADIX;
527 }
528
529 /*
530 * BLST_META_FREE() - free allocated blocks from radix tree meta info
531 *
532 * This support routine frees a range of blocks from the bitmap.
533 * The range must be entirely enclosed by this radix node. If a
534 * meta node, we break the range down recursively to free blocks
535 * in subnodes (which means that this code can free an arbitrary
536 * range whereas the allocation code cannot allocate an arbitrary
537 * range).
538 */
539
540 static void
541 blst_meta_free(
542 blmeta_t *scan,
543 daddr_t freeBlk,
544 daddr_t count,
545 daddr_t radix,
546 int skip,
547 daddr_t blk
548 ) {
549 int i;
550 int next_skip = ((u_int)skip / BLIST_META_RADIX);
551
552 #if 0
553 printf("free (%llx,%lld) FROM (%llx,%lld)\n",
554 (long long)freeBlk, (long long)count,
555 (long long)blk, (long long)radix
556 );
557 #endif
558
559 if (scan->u.bmu_avail == 0) {
560 /*
561 * ALL-ALLOCATED special case, with possible
562 * shortcut to ALL-FREE special case.
563 */
564 scan->u.bmu_avail = count;
565 scan->bm_bighint = count;
566
567 if (count != radix) {
568 for (i = 1; i <= skip; i += next_skip) {
569 if (scan[i].bm_bighint == (daddr_t)-1)
570 break;
571 scan[i].bm_bighint = 0;
572 if (next_skip == 1) {
573 scan[i].u.bmu_bitmap = 0;
574 } else {
575 scan[i].u.bmu_avail = 0;
576 }
577 }
578 /* fall through */
579 }
580 } else {
581 scan->u.bmu_avail += count;
582 /* scan->bm_bighint = radix; */
583 }
584
585 /*
586 * ALL-FREE special case.
587 */
588
589 if (scan->u.bmu_avail == radix)
590 return;
591 if (scan->u.bmu_avail > radix)
592 panic("blst_meta_free: freeing already free blocks (%lld) %lld/%lld",
593 (long long)count, (long long)scan->u.bmu_avail,
594 (long long)radix);
595
596 /*
597 * Break the free down into its components
598 */
599
600 radix /= BLIST_META_RADIX;
601
602 i = (freeBlk - blk) / radix;
603 blk += i * radix;
604 i = i * next_skip + 1;
605
606 while (i <= skip && blk < freeBlk + count) {
607 daddr_t v;
608
609 v = blk + radix - freeBlk;
610 if (v > count)
611 v = count;
612
613 if (scan->bm_bighint == (daddr_t)-1)
614 panic("blst_meta_free: freeing unexpected range");
615
616 if (next_skip == 1) {
617 blst_leaf_free(&scan[i], freeBlk, v);
618 } else {
619 blst_meta_free(&scan[i], freeBlk, v, radix, next_skip - 1, blk);
620 }
621 if (scan->bm_bighint < scan[i].bm_bighint)
622 scan->bm_bighint = scan[i].bm_bighint;
623 count -= v;
624 freeBlk += v;
625 blk += radix;
626 i += next_skip;
627 }
628 }
629
630 /*
631 * BLIST_RADIX_COPY() - copy one radix tree to another
632 *
633 * Locates free space in the source tree and frees it in the destination
634 * tree. The space may not already be free in the destination.
635 */
636
637 static void blst_copy(
638 blmeta_t *scan,
639 daddr_t blk,
640 daddr_t radix,
641 daddr_t skip,
642 blist_t dest,
643 daddr_t count
644 ) {
645 int next_skip;
646 int i;
647
648 /*
649 * Leaf node
650 */
651
652 if (radix == BLIST_BMAP_RADIX) {
653 u_daddr_t v = scan->u.bmu_bitmap;
654
655 if (v == (u_daddr_t)-1) {
656 blist_free(dest, blk, count);
657 } else if (v != 0) {
658 int i;
659
660 for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) {
661 if (v & (1 << i))
662 blist_free(dest, blk + i, 1);
663 }
664 }
665 return;
666 }
667
668 /*
669 * Meta node
670 */
671
672 if (scan->u.bmu_avail == 0) {
673 /*
674 * Source all allocated, leave dest allocated
675 */
676 return;
677 }
678 if (scan->u.bmu_avail == radix) {
679 /*
680 * Source all free, free entire dest
681 */
682 if (count < radix)
683 blist_free(dest, blk, count);
684 else
685 blist_free(dest, blk, radix);
686 return;
687 }
688
689
690 radix /= BLIST_META_RADIX;
691 next_skip = ((u_int)skip / BLIST_META_RADIX);
692
693 for (i = 1; count && i <= skip; i += next_skip) {
694 if (scan[i].bm_bighint == (daddr_t)-1)
695 break;
696
697 if (count >= radix) {
698 blst_copy(
699 &scan[i],
700 blk,
701 radix,
702 next_skip - 1,
703 dest,
704 radix
705 );
706 count -= radix;
707 } else {
708 if (count) {
709 blst_copy(
710 &scan[i],
711 blk,
712 radix,
713 next_skip - 1,
714 dest,
715 count
716 );
717 }
718 count = 0;
719 }
720 blk += radix;
721 }
722 }
723
724 /*
725 * BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap
726 *
727 * This routine allocates all blocks in the specified range
728 * regardless of any existing allocations in that range. Returns
729 * the number of blocks allocated by the call.
730 */
731
732 static int
733 blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count)
734 {
735 int n = blk & (BLIST_BMAP_RADIX - 1);
736 int nblks;
737 u_daddr_t mask, bitmap;
738
739 mask = ((u_daddr_t)-1 << n) &
740 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
741
742 /* Count the number of blocks we're about to allocate */
743 bitmap = scan->u.bmu_bitmap & mask;
744 for (nblks = 0; bitmap != 0; nblks++)
745 bitmap &= bitmap - 1;
746
747 scan->u.bmu_bitmap &= ~mask;
748 return nblks;
749 }
750
751 /*
752 * BLIST_META_FILL() - allocate specific blocks at a meta node
753 *
754 * This routine allocates the specified range of blocks,
755 * regardless of any existing allocations in the range. The
756 * range must be within the extent of this node. Returns the
757 * number of blocks allocated by the call.
758 */
759 static int
760 blst_meta_fill(
761 blmeta_t *scan,
762 daddr_t allocBlk,
763 daddr_t count,
764 daddr_t radix,
765 int skip,
766 daddr_t blk
767 ) {
768 int i;
769 int next_skip = ((u_int)skip / BLIST_META_RADIX);
770 int nblks = 0;
771
772 if (count == radix || scan->u.bmu_avail == 0) {
773 /*
774 * ALL-ALLOCATED special case
775 */
776 nblks = scan->u.bmu_avail;
777 scan->u.bmu_avail = 0;
778 scan->bm_bighint = count;
779 return nblks;
780 }
781
782 if (scan->u.bmu_avail == radix) {
783 radix /= BLIST_META_RADIX;
784
785 /*
786 * ALL-FREE special case, initialize sublevel
787 */
788 for (i = 1; i <= skip; i += next_skip) {
789 if (scan[i].bm_bighint == (daddr_t)-1)
790 break;
791 if (next_skip == 1) {
792 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
793 scan[i].bm_bighint = BLIST_BMAP_RADIX;
794 } else {
795 scan[i].bm_bighint = radix;
796 scan[i].u.bmu_avail = radix;
797 }
798 }
799 } else {
800 radix /= BLIST_META_RADIX;
801 }
802
803 if (count > radix)
804 panic("blist_meta_fill: allocation too large");
805
806 i = (allocBlk - blk) / radix;
807 blk += i * radix;
808 i = i * next_skip + 1;
809
810 while (i <= skip && blk < allocBlk + count) {
811 daddr_t v;
812
813 v = blk + radix - allocBlk;
814 if (v > count)
815 v = count;
816
817 if (scan->bm_bighint == (daddr_t)-1)
818 panic("blst_meta_fill: filling unexpected range");
819
820 if (next_skip == 1) {
821 nblks += blst_leaf_fill(&scan[i], allocBlk, v);
822 } else {
823 nblks += blst_meta_fill(&scan[i], allocBlk, v,
824 radix, next_skip - 1, blk);
825 }
826 count -= v;
827 allocBlk += v;
828 blk += radix;
829 i += next_skip;
830 }
831 scan->u.bmu_avail -= nblks;
832 return nblks;
833 }
834
835 /*
836 * BLST_RADIX_INIT() - initialize radix tree
837 *
838 * Initialize our meta structures and bitmaps and calculate the exact
839 * amount of space required to manage 'count' blocks - this space may
840 * be considerably less than the calculated radix due to the large
841 * RADIX values we use.
842 */
843
844 static daddr_t
845 blst_radix_init(blmeta_t *scan, daddr_t radix, int skip, daddr_t count)
846 {
847 int i;
848 int next_skip;
849 daddr_t memindex = 0;
850
851 /*
852 * Leaf node
853 */
854
855 if (radix == BLIST_BMAP_RADIX) {
856 if (scan) {
857 scan->bm_bighint = 0;
858 scan->u.bmu_bitmap = 0;
859 }
860 return(memindex);
861 }
862
863 /*
864 * Meta node. If allocating the entire object we can special
865 * case it. However, we need to figure out how much memory
866 * is required to manage 'count' blocks, so we continue on anyway.
867 */
868
869 if (scan) {
870 scan->bm_bighint = 0;
871 scan->u.bmu_avail = 0;
872 }
873
874 radix /= BLIST_META_RADIX;
875 next_skip = ((u_int)skip / BLIST_META_RADIX);
876
877 for (i = 1; i <= skip; i += next_skip) {
878 if (count >= radix) {
879 /*
880 * Allocate the entire object
881 */
882 memindex = i + blst_radix_init(
883 ((scan) ? &scan[i] : NULL),
884 radix,
885 next_skip - 1,
886 radix
887 );
888 count -= radix;
889 } else if (count > 0) {
890 /*
891 * Allocate a partial object
892 */
893 memindex = i + blst_radix_init(
894 ((scan) ? &scan[i] : NULL),
895 radix,
896 next_skip - 1,
897 count
898 );
899 count = 0;
900 } else {
901 /*
902 * Add terminator and break out
903 */
904 if (scan)
905 scan[i].bm_bighint = (daddr_t)-1;
906 break;
907 }
908 }
909 if (memindex < i)
910 memindex = i;
911 return(memindex);
912 }
913
914 #ifdef BLIST_DEBUG
915
916 static void
917 blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int skip, int tab)
918 {
919 int i;
920 int next_skip;
921 int lastState = 0;
922
923 if (radix == BLIST_BMAP_RADIX) {
924 printf(
925 "%*.*s(%08llx,%lld): bitmap %08llx big=%lld\n",
926 tab, tab, "",
927 (long long)blk, (long long)radix,
928 (long long)scan->u.bmu_bitmap,
929 (long long)scan->bm_bighint
930 );
931 return;
932 }
933
934 if (scan->u.bmu_avail == 0) {
935 printf(
936 "%*.*s(%08llx,%lld) ALL ALLOCATED\n",
937 tab, tab, "",
938 (long long)blk,
939 (long long)radix
940 );
941 return;
942 }
943 if (scan->u.bmu_avail == radix) {
944 printf(
945 "%*.*s(%08llx,%lld) ALL FREE\n",
946 tab, tab, "",
947 (long long)blk,
948 (long long)radix
949 );
950 return;
951 }
952
953 printf(
954 "%*.*s(%08llx,%lld): subtree (%lld/%lld) big=%lld {\n",
955 tab, tab, "",
956 (long long)blk, (long long)radix,
957 (long long)scan->u.bmu_avail,
958 (long long)radix,
959 (long long)scan->bm_bighint
960 );
961
962 radix /= BLIST_META_RADIX;
963 next_skip = ((u_int)skip / BLIST_META_RADIX);
964 tab += 4;
965
966 for (i = 1; i <= skip; i += next_skip) {
967 if (scan[i].bm_bighint == (daddr_t)-1) {
968 printf(
969 "%*.*s(%08llx,%lld): Terminator\n",
970 tab, tab, "",
971 (long long)blk, (long long)radix
972 );
973 lastState = 0;
974 break;
975 }
976 blst_radix_print(
977 &scan[i],
978 blk,
979 radix,
980 next_skip - 1,
981 tab
982 );
983 blk += radix;
984 }
985 tab -= 4;
986
987 printf(
988 "%*.*s}\n",
989 tab, tab, ""
990 );
991 }
992
993 #endif
994
995 #ifdef BLIST_DEBUG
996
997 int
998 main(int ac, char **av)
999 {
1000 int size = 1024;
1001 int i;
1002 blist_t bl;
1003
1004 for (i = 1; i < ac; ++i) {
1005 const char *ptr = av[i];
1006 if (*ptr != '-') {
1007 size = strtol(ptr, NULL, 0);
1008 continue;
1009 }
1010 ptr += 2;
1011 fprintf(stderr, "Bad option: %s\n", ptr - 2);
1012 exit(1);
1013 }
1014 bl = blist_create(size, M_WAITOK);
1015 blist_free(bl, 0, size);
1016
1017 for (;;) {
1018 char buf[1024];
1019 daddr_t da = 0;
1020 daddr_t count = 0;
1021
1022
1023 printf("%lld/%lld/%lld> ", (long long)bl->bl_free,
1024 (long long)size, (long long)bl->bl_radix);
1025 fflush(stdout);
1026 if (fgets(buf, sizeof(buf), stdin) == NULL)
1027 break;
1028 switch(buf[0]) {
1029 case 'r':
1030 if (sscanf(buf + 1, "%lld", &count) == 1) {
1031 blist_resize(&bl, count, 1);
1032 } else {
1033 printf("?\n");
1034 }
1035 case 'p':
1036 blist_print(bl);
1037 break;
1038 case 'a':
1039 if (sscanf(buf + 1, "%lld", &count) == 1) {
1040 daddr_t blk = blist_alloc(bl, count);
1041 printf(" R=%08llx\n", (long long)blk);
1042 } else {
1043 printf("?\n");
1044 }
1045 break;
1046 case 'f':
1047 if (sscanf(buf + 1, "%llx %lld",
1048 (long long *)&da, (long long *)&count) == 2) {
1049 blist_free(bl, da, count);
1050 } else {
1051 printf("?\n");
1052 }
1053 break;
1054 case 'l':
1055 if (sscanf(buf + 1, "%llx %lld",
1056 (long long *)&da, (long long *)&count) == 2) {
1057 printf(" n=%d\n",
1058 blist_fill(bl, da, count));
1059 } else {
1060 printf("?\n");
1061 }
1062 break;
1063 case '?':
1064 case 'h':
1065 puts(
1066 "p -print\n"
1067 "a %d -allocate\n"
1068 "f %x %d -free\n"
1069 "l %x %d -fill\n"
1070 "r %d -resize\n"
1071 "h/? -help"
1072 );
1073 break;
1074 default:
1075 printf("?\n");
1076 break;
1077 }
1078 }
1079 return(0);
1080 }
1081
1082 void
1083 panic(const char *ctl, ...)
1084 {
1085 va_list va;
1086
1087 va_start(va, ctl);
1088 vfprintf(stderr, ctl, va);
1089 fprintf(stderr, "\n");
1090 va_end(va);
1091 exit(1);
1092 }
1093
1094 #endif
1095
Cache object: 8d9c81db24da22d6045e08f78aa5ec03
|