2 * simple memory allocator, backed by mmap() so that it hands out memory
3 * that can be shared across processes and threads
15 #define SMALLOC_REDZONE /* define to detect memory corruption */
17 #define SMALLOC_BPB 32 /* block size, bytes-per-bit in bitmap */
18 #define SMALLOC_BPI (sizeof(unsigned int) * 8)
19 #define SMALLOC_BPL (SMALLOC_BPB * SMALLOC_BPI)
21 #define INITIAL_SIZE 16*1024*1024 /* new pool size */
22 #define INITIAL_POOLS 8 /* maximum number of pools to setup */
26 #define SMALLOC_PRE_RED 0xdeadbeefU
27 #define SMALLOC_POST_RED 0x5aa55aa5U
29 unsigned int smalloc_pool_size = INITIAL_SIZE;
30 #ifdef SMALLOC_REDZONE
31 static const int int_mask = sizeof(int) - 1;
35 struct fio_sem *lock; /* protects this pool */
36 void *map; /* map of blocks */
37 unsigned int *bitmap; /* blocks free/busy map */
38 size_t free_blocks; /* free blocks */
39 size_t nr_blocks; /* total blocks */
46 #ifdef SMALLOC_REDZONE
52 * This suppresses the voluminous potential bitmap printout when
53 * smalloc encounters an OOM error
55 static const bool enable_smalloc_debug = false;
57 static struct pool mp[MAX_POOLS];
58 static unsigned int nr_pools;
59 static unsigned int last_pool;
61 static inline int ptr_valid(struct pool *pool, void *ptr)
63 unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;
65 return (ptr >= pool->map) && (ptr < pool->map + pool_size);
68 static inline size_t size_to_blocks(size_t size)
70 return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
73 static int blocks_iter(struct pool *pool, unsigned int pool_idx,
74 unsigned int idx, size_t nr_blocks,
75 int (*func)(unsigned int *map, unsigned int mask))
79 unsigned int this_blocks, mask;
82 if (pool_idx >= pool->nr_blocks)
85 map = &pool->bitmap[pool_idx];
87 this_blocks = nr_blocks;
88 if (this_blocks + idx > SMALLOC_BPI) {
89 this_blocks = SMALLOC_BPI - idx;
90 idx = SMALLOC_BPI - this_blocks;
93 if (this_blocks == SMALLOC_BPI)
96 mask = ((1U << this_blocks) - 1) << idx;
101 nr_blocks -= this_blocks;
109 static int mask_cmp(unsigned int *map, unsigned int mask)
111 return !(*map & mask);
114 static int mask_clear(unsigned int *map, unsigned int mask)
116 assert((*map & mask) == mask);
121 static int mask_set(unsigned int *map, unsigned int mask)
123 assert(!(*map & mask));
128 static int blocks_free(struct pool *pool, unsigned int pool_idx,
129 unsigned int idx, size_t nr_blocks)
131 return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
134 static void set_blocks(struct pool *pool, unsigned int pool_idx,
135 unsigned int idx, size_t nr_blocks)
137 blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
140 static void clear_blocks(struct pool *pool, unsigned int pool_idx,
141 unsigned int idx, size_t nr_blocks)
143 blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
146 static int find_next_zero(int word, int start)
150 return ffz(word) + start;
153 static bool add_pool(struct pool *pool, unsigned int alloc_size)
159 if (nr_pools == MAX_POOLS)
162 #ifdef SMALLOC_REDZONE
163 alloc_size += sizeof(unsigned int);
165 alloc_size += sizeof(struct block_hdr);
166 if (alloc_size < INITIAL_SIZE)
167 alloc_size = INITIAL_SIZE;
169 /* round up to nearest full number of blocks */
170 alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
171 bitmap_blocks = alloc_size / SMALLOC_BPL;
172 alloc_size += bitmap_blocks * sizeof(unsigned int);
173 pool->mmap_size = alloc_size;
175 pool->nr_blocks = bitmap_blocks;
176 pool->free_blocks = bitmap_blocks * SMALLOC_BPB;
178 mmap_flags = OS_MAP_ANON;
180 mmap_flags |= MAP_PRIVATE;
182 mmap_flags |= MAP_SHARED;
184 ptr = mmap(NULL, alloc_size, PROT_READ|PROT_WRITE, mmap_flags, -1, 0);
186 if (ptr == MAP_FAILED)
190 pool->bitmap = (unsigned int *)((char *) ptr + (pool->nr_blocks * SMALLOC_BPL));
191 memset(pool->bitmap, 0, bitmap_blocks * sizeof(unsigned int));
193 pool->lock = fio_sem_init(FIO_SEM_UNLOCKED);
200 log_err("smalloc: failed adding pool\n");
202 munmap(pool->map, pool->mmap_size);
211 for (i = 0; i < INITIAL_POOLS; i++) {
212 ret = add_pool(&mp[nr_pools], smalloc_pool_size);
218 * If we added at least one pool, we should be OK for most
224 static void cleanup_pool(struct pool *pool)
227 * This will also remove the temporary file we used as a backing
228 * store, it was already unlinked
230 munmap(pool->map, pool->mmap_size);
233 fio_sem_remove(pool->lock);
240 for (i = 0; i < nr_pools; i++)
241 cleanup_pool(&mp[i]);
244 #ifdef SMALLOC_REDZONE
245 static void *postred_ptr(struct block_hdr *hdr)
249 ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
250 ptr = (uintptr_t) PTR_ALIGN(ptr, int_mask);
255 static void fill_redzone(struct block_hdr *hdr)
257 unsigned int *postred = postred_ptr(hdr);
259 hdr->prered = SMALLOC_PRE_RED;
260 *postred = SMALLOC_POST_RED;
263 static void sfree_check_redzone(struct block_hdr *hdr)
265 unsigned int *postred = postred_ptr(hdr);
267 if (hdr->prered != SMALLOC_PRE_RED) {
268 log_err("smalloc pre redzone destroyed!\n"
269 " ptr=%p, prered=%x, expected %x\n",
270 hdr, hdr->prered, SMALLOC_PRE_RED);
273 if (*postred != SMALLOC_POST_RED) {
274 log_err("smalloc post redzone destroyed!\n"
275 " ptr=%p, postred=%x, expected %x\n",
276 hdr, *postred, SMALLOC_POST_RED);
281 static void fill_redzone(struct block_hdr *hdr)
285 static void sfree_check_redzone(struct block_hdr *hdr)
290 static void sfree_pool(struct pool *pool, void *ptr)
292 struct block_hdr *hdr;
294 unsigned long offset;
302 assert(ptr_valid(pool, ptr));
304 sfree_check_redzone(hdr);
306 offset = ptr - pool->map;
307 i = offset / SMALLOC_BPL;
308 idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;
310 fio_sem_down(pool->lock);
311 clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
312 if (i < pool->next_non_full)
313 pool->next_non_full = i;
314 pool->free_blocks += size_to_blocks(hdr->size);
315 fio_sem_up(pool->lock);
318 void sfree(void *ptr)
320 struct pool *pool = NULL;
326 for (i = 0; i < nr_pools; i++) {
327 if (ptr_valid(&mp[i], ptr)) {
334 sfree_pool(pool, ptr);
338 log_err("smalloc: ptr %p not from smalloc pool\n", ptr);
341 static unsigned int find_best_index(struct pool *pool)
345 assert(pool->free_blocks);
347 for (i = pool->next_non_full; pool->bitmap[i] == -1U; i++) {
348 if (i == pool->nr_blocks - 1) {
351 for (j = 0; j < pool->nr_blocks; j++)
352 if (pool->bitmap[j] != -1U)
360 static void *__smalloc_pool(struct pool *pool, size_t size)
365 unsigned int last_idx;
368 fio_sem_down(pool->lock);
370 nr_blocks = size_to_blocks(size);
371 if (nr_blocks > pool->free_blocks)
374 pool->next_non_full = find_best_index(pool);
378 i = pool->next_non_full;
379 while (i < pool->nr_blocks) {
382 if (pool->bitmap[i] == -1U) {
388 idx = find_next_zero(pool->bitmap[i], last_idx);
389 if (!blocks_free(pool, i, idx, nr_blocks)) {
391 if (idx < SMALLOC_BPI)
395 while (idx >= SMALLOC_BPI) {
402 set_blocks(pool, i, idx, nr_blocks);
403 offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
407 if (i < pool->nr_blocks) {
408 pool->free_blocks -= nr_blocks;
409 ret = pool->map + offset;
412 fio_sem_up(pool->lock);
416 static size_t size_to_alloc_size(size_t size)
418 size_t alloc_size = size + sizeof(struct block_hdr);
421 * Round to int alignment, so that the postred pointer will
422 * be naturally aligned as well.
424 #ifdef SMALLOC_REDZONE
425 alloc_size += sizeof(unsigned int);
426 alloc_size = (alloc_size + int_mask) & ~int_mask;
432 static void *smalloc_pool(struct pool *pool, size_t size)
434 size_t alloc_size = size_to_alloc_size(size);
437 ptr = __smalloc_pool(pool, alloc_size);
439 struct block_hdr *hdr = ptr;
441 hdr->size = alloc_size;
445 memset(ptr, 0, size);
451 static void smalloc_print_bitmap(struct pool *pool)
453 size_t nr_blocks = pool->nr_blocks;
454 unsigned int *bitmap = pool->bitmap;
458 if (!enable_smalloc_debug)
461 buffer = malloc(SMALLOC_BPI + 1);
464 buffer[SMALLOC_BPI] = '\0';
466 for (i = 0; i < nr_blocks; i++) {
467 unsigned int line = bitmap[i];
469 /* skip completely full lines */
473 for (j = 0; j < SMALLOC_BPI; j++)
475 buffer[SMALLOC_BPI-1-j] = '1';
477 buffer[SMALLOC_BPI-1-j] = '0';
479 log_err("smalloc: bitmap %5u, %s\n", i, buffer);
485 void smalloc_debug(size_t size)
488 size_t alloc_size = size_to_alloc_size(size);
491 alloc_blocks = size_to_blocks(alloc_size);
494 log_err("smalloc: size = %lu, alloc_size = %lu, blocks = %lu\n",
495 (unsigned long) size, (unsigned long) alloc_size,
496 (unsigned long) alloc_blocks);
497 for (i = 0; i < nr_pools; i++) {
498 log_err("smalloc: pool %u, free/total blocks %u/%u\n", i,
499 (unsigned int) (mp[i].free_blocks),
500 (unsigned int) (mp[i].nr_blocks*sizeof(unsigned int)*8));
501 if (size && mp[i].free_blocks >= alloc_blocks) {
502 void *ptr = smalloc_pool(&mp[i], size);
506 log_err("smalloc: smalloc_pool %u succeeded\n", i);
508 log_err("smalloc: smalloc_pool %u failed\n", i);
509 log_err("smalloc: next_non_full=%u, nr_blocks=%u\n",
510 (unsigned int) mp[i].next_non_full, (unsigned int) mp[i].nr_blocks);
511 smalloc_print_bitmap(&mp[i]);
517 void *smalloc(size_t size)
519 unsigned int i, end_pool;
521 if (size != (unsigned int) size)
528 for (; i < end_pool; i++) {
529 void *ptr = smalloc_pool(&mp[i], size);
537 end_pool = last_pool;
545 log_err("smalloc: OOM. Consider using --alloc-size to increase the "
546 "shared memory available.\n");
551 void *scalloc(size_t nmemb, size_t size)
553 return smalloc(nmemb * size);
556 char *smalloc_strdup(const char *str)
560 ptr = smalloc(strlen(str) + 1);