FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_blist.c
1 /*
2 * BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting
3 *
4 * Copyright (c) 1998,2004 The DragonFly Project. All rights reserved.
5 *
6 * This code is derived from software contributed to The DragonFly Project
7 * by Matthew Dillon <dillon@backplane.com>
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 * 3. Neither the name of The DragonFly Project nor the names of its
20 * contributors may be used to endorse or promote products derived
21 * from this software without specific, prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 *
37 * This module implements a general bitmap allocator/deallocator. The
38 * allocator eats around 2 bits per 'block'. The module does not
39 * try to interpret the meaning of a 'block' other then to return
40 * SWAPBLK_NONE on an allocation failure.
41 *
42 * A radix tree is used to maintain the bitmap. Two radix constants are
43 * involved: One for the bitmaps contained in the leaf nodes (typically
44 * 32), and one for the meta nodes (typically 16). Both meta and leaf
45 * nodes have a hint field. This field gives us a hint as to the largest
46 * free contiguous range of blocks under the node. It may contain a
47 * value that is too high, but will never contain a value that is too
48 * low. When the radix tree is searched, allocation failures in subtrees
49 * update the hint.
50 *
51 * The radix tree also implements two collapsed states for meta nodes:
52 * the ALL-ALLOCATED state and the ALL-FREE state. If a meta node is
53 * in either of these two states, all information contained underneath
54 * the node is considered stale. These states are used to optimize
55 * allocation and freeing operations.
56 *
57 * The hinting greatly increases code efficiency for allocations while
58 * the general radix structure optimizes both allocations and frees. The
59 * radix tree should be able to operate well no matter how much
60 * fragmentation there is and no matter how large a bitmap is used.
61 *
62 * Unlike the rlist code, the blist code wires all necessary memory at
63 * creation time. Neither allocations nor frees require interaction with
64 * the memory subsystem. In contrast, the rlist code may allocate memory
65 * on an rlist_free() call. The non-blocking features of the blist code
66 * are used to great advantage in the swap code (vm/nswap_pager.c). The
67 * rlist code uses a little less overall memory then the blist code (but
68 * due to swap interleaving not all that much less), but the blist code
69 * scales much, much better.
70 *
71 * LAYOUT: The radix tree is layed out recursively using a
72 * linear array. Each meta node is immediately followed (layed out
73 * sequentially in memory) by BLIST_META_RADIX lower level nodes. This
74 * is a recursive structure but one that can be easily scanned through
75 * a very simple 'skip' calculation. In order to support large radixes,
76 * portions of the tree may reside outside our memory allocation. We
77 * handle this with an early-termination optimization (when bighint is
78 * set to -1) on the scan. The memory allocation is only large enough
79 * to cover the number of blocks requested at creation time even if it
80 * must be encompassed in larger root-node radix.
81 *
82 * NOTE: The allocator cannot currently allocate more then
83 * BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too
84 * large' if you try. This is an area that could use improvement. The
85 * radix is large enough that this restriction does not effect the swap
86 * system, though. Currently only the allocation code is effected by
87 * this algorithmic unfeature. The freeing code can handle arbitrary
88 * ranges.
89 *
90 * NOTE: The radix may exceed 32 bits in order to support up to 2^31
91 * blocks. The first divison will drop the radix down and fit
92 * it within a signed 32 bit integer.
93 *
94 * This code can be compiled stand-alone for debugging.
95 */
96
97 #ifdef _KERNEL
98
99 #include <sys/param.h>
100 #include <sys/systm.h>
101 #include <sys/lock.h>
102 #include <sys/kernel.h>
103 #include <sys/blist.h>
104 #include <sys/malloc.h>
105
106 #else
107
108 #ifndef BLIST_NO_DEBUG
109 #define BLIST_DEBUG
110 #endif
111
112 #define SWAPBLK_NONE ((swblk_t)-1)
113
114 #include <sys/types.h>
115 #include <stdio.h>
116 #include <string.h>
117 #include <stdlib.h>
118 #include <stdarg.h>
119
120 #define kmalloc(a,b,c) malloc(a)
121 #define kfree(a,b) free(a)
122 #define kprintf printf
123 #define KKASSERT(exp)
124
125 #include <sys/blist.h>
126
127 void panic(const char *ctl, ...);
128
129 #endif
130
131 /*
132 * static support functions
133 */
134
135 static swblk_t blst_leaf_alloc(blmeta_t *scan, swblk_t blkat,
136 swblk_t blk, int count);
137 static swblk_t blst_meta_alloc(blmeta_t *scan, swblk_t blkat,
138 swblk_t blk, swblk_t count,
139 int64_t radix, int skip);
140 static void blst_leaf_free(blmeta_t *scan, swblk_t relblk, int count);
141 static void blst_meta_free(blmeta_t *scan, swblk_t freeBlk, swblk_t count,
142 int64_t radix, int skip, swblk_t blk);
143 static swblk_t blst_leaf_fill(blmeta_t *scan, swblk_t blk, int count);
144 static swblk_t blst_meta_fill(blmeta_t *scan, swblk_t fillBlk, swblk_t count,
145 int64_t radix, int skip, swblk_t blk);
146 static void blst_copy(blmeta_t *scan, swblk_t blk, int64_t radix,
147 swblk_t skip, blist_t dest, swblk_t count);
148 static swblk_t blst_radix_init(blmeta_t *scan, int64_t radix,
149 int skip, swblk_t count);
150 #ifndef _KERNEL
151 static void blst_radix_print(blmeta_t *scan, swblk_t blk,
152 int64_t radix, int skip, int tab);
153 #endif
154
155 #ifdef _KERNEL
156 static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
157 #endif
158
159 /*
160 * blist_create() - create a blist capable of handling up to the specified
161 * number of blocks
162 *
163 * blocks must be greater then 0
164 *
165 * The smallest blist consists of a single leaf node capable of
166 * managing BLIST_BMAP_RADIX blocks.
167 */
168
169 blist_t
170 blist_create(swblk_t blocks)
171 {
172 blist_t bl;
173 int64_t radix;
174 int skip = 0;
175
176 /*
177 * Calculate radix and skip field used for scanning.
178 *
179 * Radix can exceed 32 bits even if swblk_t is limited to 32 bits.
180 */
181 radix = BLIST_BMAP_RADIX;
182
183 while (radix < blocks) {
184 radix *= BLIST_META_RADIX;
185 skip = (skip + 1) * BLIST_META_RADIX;
186 KKASSERT(skip > 0);
187 }
188
189 bl = kmalloc(sizeof(struct blist), M_SWAP, M_WAITOK | M_ZERO);
190
191 bl->bl_blocks = blocks;
192 bl->bl_radix = radix;
193 bl->bl_skip = skip;
194 bl->bl_rootblks = 1 +
195 blst_radix_init(NULL, bl->bl_radix, bl->bl_skip, blocks);
196 bl->bl_root = kmalloc(sizeof(blmeta_t) * bl->bl_rootblks, M_SWAP, M_WAITOK);
197
198 #if defined(BLIST_DEBUG)
199 kprintf(
200 "BLIST representing %d blocks (%d MB of swap)"
201 ", requiring %dK of ram\n",
202 bl->bl_blocks,
203 bl->bl_blocks * 4 / 1024,
204 (bl->bl_rootblks * sizeof(blmeta_t) + 1023) / 1024
205 );
206 kprintf("BLIST raw radix tree contains %d records\n", bl->bl_rootblks);
207 #endif
208 blst_radix_init(bl->bl_root, bl->bl_radix, bl->bl_skip, blocks);
209
210 return(bl);
211 }
212
213 void
214 blist_destroy(blist_t bl)
215 {
216 kfree(bl->bl_root, M_SWAP);
217 kfree(bl, M_SWAP);
218 }
219
220 /*
221 * blist_alloc() - reserve space in the block bitmap. Return the base
222 * of a contiguous region or SWAPBLK_NONE if space could
223 * not be allocated.
224 */
225
226 swblk_t
227 blist_alloc(blist_t bl, swblk_t count)
228 {
229 swblk_t blk = SWAPBLK_NONE;
230
231 if (bl) {
232 if (bl->bl_radix == BLIST_BMAP_RADIX)
233 blk = blst_leaf_alloc(bl->bl_root, 0, 0, count);
234 else
235 blk = blst_meta_alloc(bl->bl_root, 0, 0, count,
236 bl->bl_radix, bl->bl_skip);
237 if (blk != SWAPBLK_NONE)
238 bl->bl_free -= count;
239 }
240 return(blk);
241 }
242
243 swblk_t
244 blist_allocat(blist_t bl, swblk_t count, swblk_t blkat)
245 {
246 swblk_t blk = SWAPBLK_NONE;
247
248 if (bl) {
249 if (bl->bl_radix == BLIST_BMAP_RADIX)
250 blk = blst_leaf_alloc(bl->bl_root, blkat, 0, count);
251 else
252 blk = blst_meta_alloc(bl->bl_root, blkat, 0, count,
253 bl->bl_radix, bl->bl_skip);
254 if (blk != SWAPBLK_NONE)
255 bl->bl_free -= count;
256 }
257 return(blk);
258 }
259
260 /*
261 * blist_free() - free up space in the block bitmap. Return the base
262 * of a contiguous region. Panic if an inconsistancy is
263 * found.
264 */
265
266 void
267 blist_free(blist_t bl, swblk_t blkno, swblk_t count)
268 {
269 if (bl) {
270 if (bl->bl_radix == BLIST_BMAP_RADIX)
271 blst_leaf_free(bl->bl_root, blkno, count);
272 else
273 blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0);
274 bl->bl_free += count;
275 }
276 }
277
278 /*
279 * blist_fill() - mark a region in the block bitmap as off-limits
280 * to the allocator (i.e. allocate it), ignoring any
281 * existing allocations. Return the number of blocks
282 * actually filled that were free before the call.
283 */
284
285 swblk_t
286 blist_fill(blist_t bl, swblk_t blkno, swblk_t count)
287 {
288 swblk_t filled;
289
290 if (bl) {
291 if (bl->bl_radix == BLIST_BMAP_RADIX) {
292 filled = blst_leaf_fill(bl->bl_root, blkno, count);
293 } else {
294 filled = blst_meta_fill(bl->bl_root, blkno, count,
295 bl->bl_radix, bl->bl_skip, 0);
296 }
297 bl->bl_free -= filled;
298 return (filled);
299 } else {
300 return 0;
301 }
302 }
303
304 /*
305 * blist_resize() - resize an existing radix tree to handle the
306 * specified number of blocks. This will reallocate
307 * the tree and transfer the previous bitmap to the new
308 * one. When extending the tree you can specify whether
309 * the new blocks are to left allocated or freed.
310 */
311
312 void
313 blist_resize(blist_t *pbl, swblk_t count, int freenew)
314 {
315 blist_t newbl = blist_create(count);
316 blist_t save = *pbl;
317
318 *pbl = newbl;
319 if (count > save->bl_blocks)
320 count = save->bl_blocks;
321 blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, newbl, count);
322
323 /*
324 * If resizing upwards, should we free the new space or not?
325 */
326 if (freenew && count < newbl->bl_blocks) {
327 blist_free(newbl, count, newbl->bl_blocks - count);
328 }
329 blist_destroy(save);
330 }
331
332 #ifdef BLIST_DEBUG
333
334 /*
335 * blist_print() - dump radix tree
336 */
337
338 void
339 blist_print(blist_t bl)
340 {
341 kprintf("BLIST {\n");
342 blst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4);
343 kprintf("}\n");
344 }
345
346 #endif
347
348 /************************************************************************
349 * ALLOCATION SUPPORT FUNCTIONS *
350 ************************************************************************
351 *
352 * These support functions do all the actual work. They may seem
353 * rather longish, but that's because I've commented them up. The
354 * actual code is straight forward.
355 *
356 */
357
358 /*
359 * blist_leaf_alloc() - allocate at a leaf in the radix tree (a bitmap).
360 *
361 * This is the core of the allocator and is optimized for the 1 block
362 * and the BLIST_BMAP_RADIX block allocation cases. Other cases are
363 * somewhat slower. The 1 block allocation case is log2 and extremely
364 * quick.
365 */
366
367 static swblk_t
368 blst_leaf_alloc(blmeta_t *scan, swblk_t blkat __unused, swblk_t blk, int count)
369 {
370 u_swblk_t orig = scan->u.bmu_bitmap;
371
372 if (orig == 0) {
373 /*
374 * Optimize bitmap all-allocated case. Also, count = 1
375 * case assumes at least 1 bit is free in the bitmap, so
376 * we have to take care of this case here.
377 */
378 scan->bm_bighint = 0;
379 return(SWAPBLK_NONE);
380 }
381 if (count == 1) {
382 /*
383 * Optimized code to allocate one bit out of the bitmap
384 */
385 u_swblk_t mask;
386 int j = BLIST_BMAP_RADIX/2;
387 int r = 0;
388
389 mask = (u_swblk_t)-1 >> (BLIST_BMAP_RADIX/2);
390
391 while (j) {
392 if ((orig & mask) == 0) {
393 r += j;
394 orig >>= j;
395 }
396 j >>= 1;
397 mask >>= j;
398 }
399 scan->u.bmu_bitmap &= ~(1 << r);
400 return(blk + r);
401 }
402 if (count <= BLIST_BMAP_RADIX) {
403 /*
404 * non-optimized code to allocate N bits out of the bitmap.
405 * The more bits, the faster the code runs. It will run
406 * the slowest allocating 2 bits, but since there aren't any
407 * memory ops in the core loop (or shouldn't be, anyway),
408 * you probably won't notice the difference.
409 */
410 int j;
411 int n = BLIST_BMAP_RADIX - count;
412 u_swblk_t mask;
413
414 mask = (u_swblk_t)-1 >> n;
415
416 for (j = 0; j <= n; ++j) {
417 if ((orig & mask) == mask) {
418 scan->u.bmu_bitmap &= ~mask;
419 return(blk + j);
420 }
421 mask = (mask << 1);
422 }
423 }
424 /*
425 * We couldn't allocate count in this subtree, update bighint.
426 */
427 scan->bm_bighint = count - 1;
428 return(SWAPBLK_NONE);
429 }
430
431 /*
432 * blist_meta_alloc() - allocate at a meta in the radix tree.
433 *
434 * Attempt to allocate at a meta node. If we can't, we update
435 * bighint and return a failure. Updating bighint optimize future
436 * calls that hit this node. We have to check for our collapse cases
437 * and we have a few optimizations strewn in as well.
438 */
439 static swblk_t
440 blst_meta_alloc(blmeta_t *scan, swblk_t blkat,
441 swblk_t blk, swblk_t count,
442 int64_t radix, int skip)
443 {
444 int i;
445 int next_skip = ((u_int)skip / BLIST_META_RADIX);
446 int hintok = (blk >= blkat);
447
448 /*
449 * ALL-ALLOCATED special case
450 */
451 if (scan->u.bmu_avail == 0) {
452 scan->bm_bighint = 0;
453 return(SWAPBLK_NONE);
454 }
455
456 /*
457 * ALL-FREE special case, initialize uninitialized
458 * sublevel.
459 *
460 * NOTE: radix may exceed 32 bits until first division.
461 */
462 if (scan->u.bmu_avail == radix) {
463 scan->bm_bighint = radix;
464
465 radix /= BLIST_META_RADIX;
466 for (i = 1; i <= skip; i += next_skip) {
467 if (scan[i].bm_bighint == (swblk_t)-1)
468 break;
469 if (next_skip == 1) {
470 scan[i].u.bmu_bitmap = (u_swblk_t)-1;
471 scan[i].bm_bighint = BLIST_BMAP_RADIX;
472 } else {
473 scan[i].bm_bighint = (swblk_t)radix;
474 scan[i].u.bmu_avail = (swblk_t)radix;
475 }
476 }
477 } else {
478 radix /= BLIST_META_RADIX;
479 }
480
481 for (i = 1; i <= skip; i += next_skip) {
482 if (count <= scan[i].bm_bighint &&
483 blk + (swblk_t)radix > blkat) {
484 /*
485 * count fits in object
486 */
487 swblk_t r;
488 if (next_skip == 1) {
489 r = blst_leaf_alloc(&scan[i], blkat,
490 blk, count);
491 } else {
492 r = blst_meta_alloc(&scan[i], blkat,
493 blk, count,
494 radix, next_skip - 1);
495 }
496 if (r != SWAPBLK_NONE) {
497 scan->u.bmu_avail -= count;
498 if (scan->bm_bighint > scan->u.bmu_avail)
499 scan->bm_bighint = scan->u.bmu_avail;
500 return(r);
501 }
502 /* bighint was updated by recursion */
503 } else if (scan[i].bm_bighint == (swblk_t)-1) {
504 /*
505 * Terminator
506 */
507 break;
508 } else if (count > (swblk_t)radix) {
509 /*
510 * count does not fit in object even if it were
511 * complete free.
512 */
513 panic("blist_meta_alloc: allocation too large");
514 }
515 blk += (swblk_t)radix;
516 }
517
518 /*
519 * We couldn't allocate count in this subtree, update bighint.
520 */
521 if (hintok && scan->bm_bighint >= count)
522 scan->bm_bighint = count - 1;
523 return(SWAPBLK_NONE);
524 }
525
526 /*
527 * BLST_LEAF_FREE() - free allocated block from leaf bitmap
528 */
529 static void
530 blst_leaf_free(blmeta_t *scan, swblk_t blk, int count)
531 {
532 /*
533 * free some data in this bitmap
534 *
535 * e.g.
536 * 0000111111111110000
537 * \_________/\__/
538 * v n
539 */
540 int n = blk & (BLIST_BMAP_RADIX - 1);
541 u_swblk_t mask;
542
543 mask = ((u_swblk_t)-1 << n) &
544 ((u_swblk_t)-1 >> (BLIST_BMAP_RADIX - count - n));
545
546 if (scan->u.bmu_bitmap & mask)
547 panic("blst_radix_free: freeing free block");
548 scan->u.bmu_bitmap |= mask;
549
550 /*
551 * We could probably do a better job here. We are required to make
552 * bighint at least as large as the biggest contiguous block of
553 * data. If we just shoehorn it, a little extra overhead will
554 * be incured on the next allocation (but only that one typically).
555 */
556 scan->bm_bighint = BLIST_BMAP_RADIX;
557 }
558
559 /*
560 * BLST_META_FREE() - free allocated blocks from radix tree meta info
561 *
562 * This support routine frees a range of blocks from the bitmap.
563 * The range must be entirely enclosed by this radix node. If a
564 * meta node, we break the range down recursively to free blocks
565 * in subnodes (which means that this code can free an arbitrary
566 * range whereas the allocation code cannot allocate an arbitrary
567 * range).
568 */
569
570 static void
571 blst_meta_free(blmeta_t *scan, swblk_t freeBlk, swblk_t count,
572 int64_t radix, int skip, swblk_t blk)
573 {
574 int i;
575 int next_skip = ((u_int)skip / BLIST_META_RADIX);
576
577 #if 0
578 kprintf("FREE (%x,%d) FROM (%x,%lld)\n",
579 freeBlk, count,
580 blk, (long long)radix
581 );
582 #endif
583
584 /*
585 * ALL-ALLOCATED special case, initialize for recursion.
586 *
587 * We will short-cut the ALL-ALLOCATED -> ALL-FREE case.
588 */
589 if (scan->u.bmu_avail == 0) {
590 scan->u.bmu_avail = count;
591 scan->bm_bighint = count;
592
593 if (count != radix) {
594 for (i = 1; i <= skip; i += next_skip) {
595 if (scan[i].bm_bighint == (swblk_t)-1)
596 break;
597 scan[i].bm_bighint = 0;
598 if (next_skip == 1) {
599 scan[i].u.bmu_bitmap = 0;
600 } else {
601 scan[i].u.bmu_avail = 0;
602 }
603 }
604 /* fall through */
605 }
606 } else {
607 scan->u.bmu_avail += count;
608 /* scan->bm_bighint = radix; */
609 }
610
611 /*
612 * ALL-FREE special case.
613 *
614 * Set bighint for higher levels to snoop.
615 */
616 if (scan->u.bmu_avail == radix) {
617 scan->bm_bighint = radix;
618 return;
619 }
620
621 /*
622 * Break the free down into its components
623 */
624 if (scan->u.bmu_avail > radix) {
625 panic("blst_meta_free: freeing already "
626 "free blocks (%d) %d/%lld",
627 count, scan->u.bmu_avail, (long long)radix);
628 }
629
630 radix /= BLIST_META_RADIX;
631
632 i = (freeBlk - blk) / (swblk_t)radix;
633 blk += i * (swblk_t)radix;
634 i = i * next_skip + 1;
635
636 while (i <= skip && blk < freeBlk + count) {
637 swblk_t v;
638
639 v = blk + (swblk_t)radix - freeBlk;
640 if (v > count)
641 v = count;
642
643 if (scan->bm_bighint == (swblk_t)-1)
644 panic("blst_meta_free: freeing unexpected range");
645
646 if (next_skip == 1) {
647 blst_leaf_free(&scan[i], freeBlk, v);
648 } else {
649 blst_meta_free(&scan[i], freeBlk, v,
650 radix, next_skip - 1, blk);
651 }
652
653 /*
654 * After having dealt with the becomes-all-free case any
655 * partial free will not be able to bring us to the
656 * becomes-all-free state.
657 *
658 * We can raise bighint to at least the sub-segment's
659 * bighint.
660 */
661 if (scan->bm_bighint < scan[i].bm_bighint) {
662 scan->bm_bighint = scan[i].bm_bighint;
663 }
664 count -= v;
665 freeBlk += v;
666 blk += (swblk_t)radix;
667 i += next_skip;
668 }
669 }
670
671 /*
672 * BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap
673 *
674 * Allocates all blocks in the specified range regardless of
675 * any existing allocations in that range. Returns the number
676 * of blocks allocated by the call.
677 */
678 static swblk_t
679 blst_leaf_fill(blmeta_t *scan, swblk_t blk, int count)
680 {
681 int n = blk & (BLIST_BMAP_RADIX - 1);
682 swblk_t nblks;
683 u_swblk_t mask, bitmap;
684
685 mask = ((u_swblk_t)-1 << n) &
686 ((u_swblk_t)-1 >> (BLIST_BMAP_RADIX - count - n));
687
688 /* Count the number of blocks we're about to allocate */
689 bitmap = scan->u.bmu_bitmap & mask;
690 for (nblks = 0; bitmap != 0; nblks++)
691 bitmap &= bitmap - 1;
692
693 scan->u.bmu_bitmap &= ~mask;
694 return (nblks);
695 }
696
697 /*
698 * BLST_META_FILL() - allocate specific blocks at a meta node
699 *
700 * Allocates the specified range of blocks, regardless of
701 * any existing allocations in the range. The range must
702 * be within the extent of this node. Returns the number
703 * of blocks allocated by the call.
704 */
705 static swblk_t
706 blst_meta_fill(blmeta_t *scan, swblk_t fillBlk, swblk_t count,
707 int64_t radix, int skip, swblk_t blk)
708 {
709 int i;
710 int next_skip = ((u_int)skip / BLIST_META_RADIX);
711 swblk_t nblks = 0;
712
713 if (count == radix || scan->u.bmu_avail == 0) {
714 /*
715 * ALL-ALLOCATED special case
716 */
717 nblks = scan->u.bmu_avail;
718 scan->u.bmu_avail = 0;
719 scan->bm_bighint = count;
720 return (nblks);
721 }
722
723 if (scan->u.bmu_avail == radix) {
724 radix /= BLIST_META_RADIX;
725
726 /*
727 * ALL-FREE special case, initialize sublevel
728 */
729 for (i = 1; i <= skip; i += next_skip) {
730 if (scan[i].bm_bighint == (swblk_t)-1)
731 break;
732 if (next_skip == 1) {
733 scan[i].u.bmu_bitmap = (u_swblk_t)-1;
734 scan[i].bm_bighint = BLIST_BMAP_RADIX;
735 } else {
736 scan[i].bm_bighint = (swblk_t)radix;
737 scan[i].u.bmu_avail = (swblk_t)radix;
738 }
739 }
740 } else {
741 radix /= BLIST_META_RADIX;
742 }
743
744 if (count > (swblk_t)radix)
745 panic("blst_meta_fill: allocation too large");
746
747 i = (fillBlk - blk) / (swblk_t)radix;
748 blk += i * (swblk_t)radix;
749 i = i * next_skip + 1;
750
751 while (i <= skip && blk < fillBlk + count) {
752 swblk_t v;
753
754 v = blk + (swblk_t)radix - fillBlk;
755 if (v > count)
756 v = count;
757
758 if (scan->bm_bighint == (swblk_t)-1)
759 panic("blst_meta_fill: filling unexpected range");
760
761 if (next_skip == 1) {
762 nblks += blst_leaf_fill(&scan[i], fillBlk, v);
763 } else {
764 nblks += blst_meta_fill(&scan[i], fillBlk, v,
765 radix, next_skip - 1, blk);
766 }
767 count -= v;
768 fillBlk += v;
769 blk += (swblk_t)radix;
770 i += next_skip;
771 }
772 scan->u.bmu_avail -= nblks;
773 return (nblks);
774 }
775
776 /*
777 * BLIST_RADIX_COPY() - copy one radix tree to another
778 *
779 * Locates free space in the source tree and frees it in the destination
780 * tree. The space may not already be free in the destination.
781 */
782
783 static void
784 blst_copy(blmeta_t *scan, swblk_t blk, int64_t radix,
785 swblk_t skip, blist_t dest, swblk_t count)
786 {
787 int next_skip;
788 int i;
789
790 /*
791 * Leaf node
792 */
793
794 if (radix == BLIST_BMAP_RADIX) {
795 u_swblk_t v = scan->u.bmu_bitmap;
796
797 if (v == (u_swblk_t)-1) {
798 blist_free(dest, blk, count);
799 } else if (v != 0) {
800 int i;
801
802 for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) {
803 if (v & (1 << i))
804 blist_free(dest, blk + i, 1);
805 }
806 }
807 return;
808 }
809
810 /*
811 * Meta node
812 */
813
814 if (scan->u.bmu_avail == 0) {
815 /*
816 * Source all allocated, leave dest allocated
817 */
818 return;
819 }
820 if (scan->u.bmu_avail == radix) {
821 /*
822 * Source all free, free entire dest
823 */
824 if (count < radix)
825 blist_free(dest, blk, count);
826 else
827 blist_free(dest, blk, (swblk_t)radix);
828 return;
829 }
830
831
832 radix /= BLIST_META_RADIX;
833 next_skip = ((u_int)skip / BLIST_META_RADIX);
834
835 for (i = 1; count && i <= skip; i += next_skip) {
836 if (scan[i].bm_bighint == (swblk_t)-1)
837 break;
838
839 if (count >= (swblk_t)radix) {
840 blst_copy(
841 &scan[i],
842 blk,
843 radix,
844 next_skip - 1,
845 dest,
846 (swblk_t)radix
847 );
848 count -= (swblk_t)radix;
849 } else {
850 if (count) {
851 blst_copy(
852 &scan[i],
853 blk,
854 radix,
855 next_skip - 1,
856 dest,
857 count
858 );
859 }
860 count = 0;
861 }
862 blk += (swblk_t)radix;
863 }
864 }
865
866 /*
867 * BLST_RADIX_INIT() - initialize radix tree
868 *
869 * Initialize our meta structures and bitmaps and calculate the exact
870 * amount of space required to manage 'count' blocks - this space may
871 * be considerably less then the calculated radix due to the large
872 * RADIX values we use.
873 */
874
875 static swblk_t
876 blst_radix_init(blmeta_t *scan, int64_t radix, int skip, swblk_t count)
877 {
878 int i;
879 int next_skip;
880 swblk_t memindex = 0;
881
882 /*
883 * Leaf node
884 */
885
886 if (radix == BLIST_BMAP_RADIX) {
887 if (scan) {
888 scan->bm_bighint = 0;
889 scan->u.bmu_bitmap = 0;
890 }
891 return(memindex);
892 }
893
894 /*
895 * Meta node. If allocating the entire object we can special
896 * case it. However, we need to figure out how much memory
897 * is required to manage 'count' blocks, so we continue on anyway.
898 */
899
900 if (scan) {
901 scan->bm_bighint = 0;
902 scan->u.bmu_avail = 0;
903 }
904
905 radix /= BLIST_META_RADIX;
906 next_skip = ((u_int)skip / BLIST_META_RADIX);
907
908 for (i = 1; i <= skip; i += next_skip) {
909 if (count >= (swblk_t)radix) {
910 /*
911 * Allocate the entire object
912 */
913 memindex = i + blst_radix_init(
914 ((scan) ? &scan[i] : NULL),
915 radix,
916 next_skip - 1,
917 (swblk_t)radix
918 );
919 count -= (swblk_t)radix;
920 } else if (count > 0) {
921 /*
922 * Allocate a partial object
923 */
924 memindex = i + blst_radix_init(
925 ((scan) ? &scan[i] : NULL),
926 radix,
927 next_skip - 1,
928 count
929 );
930 count = 0;
931 } else {
932 /*
933 * Add terminator and break out
934 */
935 if (scan)
936 scan[i].bm_bighint = (swblk_t)-1;
937 break;
938 }
939 }
940 if (memindex < i)
941 memindex = i;
942 return(memindex);
943 }
944
945 #ifdef BLIST_DEBUG
946
947 static void
948 blst_radix_print(blmeta_t *scan, swblk_t blk, int64_t radix, int skip, int tab)
949 {
950 int i;
951 int next_skip;
952
953 if (radix == BLIST_BMAP_RADIX) {
954 kprintf(
955 "%*.*s(%04x,%lld): bitmap %08x big=%d\n",
956 tab, tab, "",
957 blk, (long long)radix,
958 scan->u.bmu_bitmap,
959 scan->bm_bighint
960 );
961 return;
962 }
963
964 if (scan->u.bmu_avail == 0) {
965 kprintf(
966 "%*.*s(%04x,%lld) ALL ALLOCATED\n",
967 tab, tab, "",
968 blk,
969 (long long)radix
970 );
971 return;
972 }
973 if (scan->u.bmu_avail == radix) {
974 kprintf(
975 "%*.*s(%04x,%lld) ALL FREE\n",
976 tab, tab, "",
977 blk,
978 (long long)radix
979 );
980 return;
981 }
982
983 kprintf(
984 "%*.*s(%04x,%lld): subtree (%d/%lld) big=%d {\n",
985 tab, tab, "",
986 blk, (long long)radix,
987 scan->u.bmu_avail,
988 (long long)radix,
989 scan->bm_bighint
990 );
991
992 radix /= BLIST_META_RADIX;
993 next_skip = ((u_int)skip / BLIST_META_RADIX);
994 tab += 4;
995
996 for (i = 1; i <= skip; i += next_skip) {
997 if (scan[i].bm_bighint == (swblk_t)-1) {
998 kprintf(
999 "%*.*s(%04x,%lld): Terminator\n",
1000 tab, tab, "",
1001 blk, (long long)radix
1002 );
1003 break;
1004 }
1005 blst_radix_print(
1006 &scan[i],
1007 blk,
1008 radix,
1009 next_skip - 1,
1010 tab
1011 );
1012 blk += (swblk_t)radix;
1013 }
1014 tab -= 4;
1015
1016 kprintf(
1017 "%*.*s}\n",
1018 tab, tab, ""
1019 );
1020 }
1021
1022 #endif
1023
1024 #ifdef BLIST_DEBUG
1025
1026 int
1027 main(int ac, char **av)
1028 {
1029 int size = 1024;
1030 int i;
1031 blist_t bl;
1032
1033 for (i = 1; i < ac; ++i) {
1034 const char *ptr = av[i];
1035 if (*ptr != '-') {
1036 size = strtol(ptr, NULL, 0);
1037 continue;
1038 }
1039 ptr += 2;
1040 fprintf(stderr, "Bad option: %s\n", ptr - 2);
1041 exit(1);
1042 }
1043 bl = blist_create(size);
1044 blist_free(bl, 0, size);
1045
1046 for (;;) {
1047 char buf[1024];
1048 swblk_t da = 0;
1049 swblk_t count = 0;
1050 swblk_t blkat;
1051
1052
1053 kprintf("%d/%d/%lld> ",
1054 bl->bl_free, size, (long long)bl->bl_radix);
1055 fflush(stdout);
1056 if (fgets(buf, sizeof(buf), stdin) == NULL)
1057 break;
1058 switch(buf[0]) {
1059 case 'r':
1060 if (sscanf(buf + 1, "%d", &count) == 1) {
1061 blist_resize(&bl, count, 1);
1062 size = count;
1063 } else {
1064 kprintf("?\n");
1065 }
1066 case 'p':
1067 blist_print(bl);
1068 break;
1069 case 'a':
1070 if (sscanf(buf + 1, "%d %d", &count, &blkat) == 1) {
1071 swblk_t blk = blist_alloc(bl, count);
1072 kprintf(" R=%04x\n", blk);
1073 } else if (sscanf(buf + 1, "%d %d", &count, &blkat) == 2) {
1074 swblk_t blk = blist_allocat(bl, count, blkat);
1075 kprintf(" R=%04x\n", blk);
1076 } else {
1077 kprintf("?\n");
1078 }
1079 break;
1080 case 'f':
1081 if (sscanf(buf + 1, "%x %d", &da, &count) == 2) {
1082 blist_free(bl, da, count);
1083 } else {
1084 kprintf("?\n");
1085 }
1086 break;
1087 case 'l':
1088 if (sscanf(buf + 1, "%x %d", &da, &count) == 2) {
1089 printf(" n=%d\n",
1090 blist_fill(bl, da, count));
1091 } else {
1092 kprintf("?\n");
1093 }
1094 break;
1095 case '?':
1096 case 'h':
1097 puts(
1098 "p -print\n"
1099 "a %d -allocate\n"
1100 "f %x %d -free\n"
1101 "l %x %d -fill\n"
1102 "r %d -resize\n"
1103 "h/? -help"
1104 );
1105 break;
1106 default:
1107 kprintf("?\n");
1108 break;
1109 }
1110 }
1111 return(0);
1112 }
1113
1114 void
1115 panic(const char *ctl, ...)
1116 {
1117 __va_list va;
1118
1119 __va_start(va, ctl);
1120 vfprintf(stderr, ctl, va);
1121 fprintf(stderr, "\n");
1122 __va_end(va);
1123 exit(1);
1124 }
1125
1126 #endif
1127
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