smalloc.c - pub/scm/linux/kernel/git/axboe/fio - Git at Google

 /*
  * simple memory allocator, backed by mmap() so that it hands out memory
  * that can be shared across processes and threads
  */
 #include <sys/mman.h>
 #include <assert.h>
 #include <string.h>

 #include "fio.h"
 #include "fio_sem.h"
 #include "os/os.h"
 #include "smalloc.h"
 #include "log.h"

 #define SMALLOC_REDZONE		/* define to detect memory corruption */

 #define SMALLOC_BPB	32	/* block size, bytes-per-bit in bitmap */
 #define SMALLOC_BPI	(sizeof(unsigned int) * 8)
 #define SMALLOC_BPL	(SMALLOC_BPB * SMALLOC_BPI)

 #define INITIAL_SIZE	16*1024*1024	/* new pool size */
 #define INITIAL_POOLS	8		/* maximum number of pools to setup */

 #define MAX_POOLS	16

 #define SMALLOC_PRE_RED		0xdeadbeefU
 #define SMALLOC_POST_RED	0x5aa55aa5U

 unsigned int smalloc_pool_size = INITIAL_SIZE;
 #ifdef SMALLOC_REDZONE
 static const int int_mask = sizeof(int) - 1;
 #endif

 struct pool {
 	struct fio_sem *lock;			/* protects this pool */
 	void *map;				/* map of blocks */
 	unsigned int *bitmap;			/* blocks free/busy map */
 	size_t free_blocks;		/* free blocks */
 	size_t nr_blocks;			/* total blocks */
 	size_t next_non_full;
 	size_t mmap_size;
 };

 struct block_hdr {
 	size_t size;
 #ifdef SMALLOC_REDZONE
 	unsigned int prered;
 #endif
 };

 /*
  * This suppresses the voluminous potential bitmap printout when
  * smalloc encounters an OOM error
  */
 static const bool enable_smalloc_debug = false;

 static struct pool *mp;
 static unsigned int nr_pools;
 static unsigned int last_pool;

 static inline int ptr_valid(struct pool *pool, void *ptr)
 {
 	unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;

 	return (ptr >= pool->map) && (ptr < pool->map + pool_size);
 }

 static inline size_t size_to_blocks(size_t size)
 {
 	return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
 }

 static int blocks_iter(struct pool *pool, unsigned int pool_idx,
 		       unsigned int idx, size_t nr_blocks,
 		       int (*func)(unsigned int *map, unsigned int mask))
 {

 	while (nr_blocks) {
 		unsigned int this_blocks, mask;
 		unsigned int *map;

 		if (pool_idx >= pool->nr_blocks)
 			return 0;

 		map = &pool->bitmap[pool_idx];

 		this_blocks = nr_blocks;
 		if (this_blocks + idx > SMALLOC_BPI) {
 			this_blocks = SMALLOC_BPI - idx;
 			idx = SMALLOC_BPI - this_blocks;
 		}

 		if (this_blocks == SMALLOC_BPI)
 			mask = -1U;
 		else
 			mask = ((1U << this_blocks) - 1) << idx;

 		if (!func(map, mask))
 			return 0;

 		nr_blocks -= this_blocks;
 		idx = 0;
 		pool_idx++;
 	}

 	return 1;
 }

 static int mask_cmp(unsigned int *map, unsigned int mask)
 {
 	return !(*map & mask);
 }

 static int mask_clear(unsigned int *map, unsigned int mask)
 {
 	assert((*map & mask) == mask);
 	*map &= ~mask;
 	return 1;
 }

 static int mask_set(unsigned int *map, unsigned int mask)
 {
 	assert(!(*map & mask));
 	*map |= mask;
 	return 1;
 }

 static int blocks_free(struct pool *pool, unsigned int pool_idx,
 		       unsigned int idx, size_t nr_blocks)
 {
 	return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
 }

 static void set_blocks(struct pool *pool, unsigned int pool_idx,
 		       unsigned int idx, size_t nr_blocks)
 {
 	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
 }

 static void clear_blocks(struct pool *pool, unsigned int pool_idx,
 			 unsigned int idx, size_t nr_blocks)
 {
 	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
 }

 static int find_next_zero(int word, int start)
 {
 	assert(word != -1U);
 	word >>= start;
 	return ffz(word) + start;
 }

 static bool add_pool(struct pool *pool, unsigned int alloc_size)
 {
 	int bitmap_blocks;
 	int mmap_flags;
 	void *ptr;

 	if (nr_pools == MAX_POOLS)
 		return false;

 #ifdef SMALLOC_REDZONE
 	alloc_size += sizeof(unsigned int);
 #endif
 	alloc_size += sizeof(struct block_hdr);
 	if (alloc_size < INITIAL_SIZE)
 		alloc_size = INITIAL_SIZE;

 	/* round up to nearest full number of blocks */
 	alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
 	bitmap_blocks = alloc_size / SMALLOC_BPL;
 	alloc_size += bitmap_blocks * sizeof(unsigned int);
 	pool->mmap_size = alloc_size;

 	pool->nr_blocks = bitmap_blocks;
 	pool->free_blocks = bitmap_blocks * SMALLOC_BPI;

 	mmap_flags = OS_MAP_ANON;
 #ifdef CONFIG_ESX
 	mmap_flags |= MAP_PRIVATE;
 #else
 	mmap_flags |= MAP_SHARED;
 #endif
 	ptr = mmap(NULL, alloc_size, PROT_READ|PROT_WRITE, mmap_flags, -1, 0);

 	if (ptr == MAP_FAILED)
 		goto out_fail;

 	pool->map = ptr;
 	pool->bitmap = (unsigned int *)((char *) ptr + (pool->nr_blocks * SMALLOC_BPL));
 	memset(pool->bitmap, 0, bitmap_blocks * sizeof(unsigned int));

 	pool->lock = fio_sem_init(FIO_SEM_UNLOCKED);
 	if (!pool->lock)
 		goto out_fail;

 	nr_pools++;
 	return true;
 out_fail:
 	log_err("smalloc: failed adding pool\n");
 	if (pool->map)
 		munmap(pool->map, pool->mmap_size);
 	return false;
 }

 void sinit(void)
 {
 	bool ret;
 	int i;

 	/*
 	 * sinit() can be called more than once if alloc-size is
 	 * set. But we want to allocate space for the struct pool
 	 * instances only once.
 	 */
 	if (!mp) {
 		mp = (struct pool *) mmap(NULL,
 			MAX_POOLS * sizeof(struct pool),
 			PROT_READ | PROT_WRITE,
 			OS_MAP_ANON | MAP_SHARED, -1, 0);

 		assert(mp != MAP_FAILED);
 	}

 	for (i = 0; i < INITIAL_POOLS; i++) {
 		ret = add_pool(&mp[nr_pools], smalloc_pool_size);
 		if (!ret)
 			break;
 	}

 	/*
 	 * If we added at least one pool, we should be OK for most
 	 * cases.
 	 */
 	assert(i);
 }

 static void cleanup_pool(struct pool *pool)
 {
 	/*
 	 * This will also remove the temporary file we used as a backing
 	 * store, it was already unlinked
 	 */
 	munmap(pool->map, pool->mmap_size);

 	if (pool->lock)
 		fio_sem_remove(pool->lock);
 }

 void scleanup(void)
 {
 	unsigned int i;

 	for (i = 0; i < nr_pools; i++)
 		cleanup_pool(&mp[i]);

 	munmap(mp, MAX_POOLS * sizeof(struct pool));
 }

 #ifdef SMALLOC_REDZONE
 static void *postred_ptr(struct block_hdr *hdr)
 {
 	uintptr_t ptr;

 	ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
 	ptr = (uintptr_t) PTR_ALIGN(ptr, int_mask);

 	return (void *) ptr;
 }

 static void fill_redzone(struct block_hdr *hdr)
 {
 	unsigned int *postred = postred_ptr(hdr);

 	hdr->prered = SMALLOC_PRE_RED;
 	*postred = SMALLOC_POST_RED;
 }

 static void sfree_check_redzone(struct block_hdr *hdr)
 {
 	unsigned int *postred = postred_ptr(hdr);

 	if (hdr->prered != SMALLOC_PRE_RED) {
 		log_err("smalloc pre redzone destroyed!\n"
 			" ptr=%p, prered=%x, expected %x\n",
 				hdr+1, hdr->prered, SMALLOC_PRE_RED);
 		assert(0);
 	}
 	if (*postred != SMALLOC_POST_RED) {
 		log_err("smalloc post redzone destroyed!\n"
 			"  ptr=%p, postred=%x, expected %x\n",
 				hdr+1, *postred, SMALLOC_POST_RED);
 		assert(0);
 	}
 }
 #else
 static void fill_redzone(struct block_hdr *hdr)
 {
 }

 static void sfree_check_redzone(struct block_hdr *hdr)
 {
 }
 #endif

 static void sfree_pool(struct pool *pool, void *ptr)
 {
 	struct block_hdr *hdr;
 	unsigned int i, idx;
 	unsigned long offset;

 	if (!ptr)
 		return;

 	ptr -= sizeof(*hdr);
 	hdr = ptr;

 	assert(ptr_valid(pool, ptr));

 	sfree_check_redzone(hdr);

 	offset = ptr - pool->map;
 	i = offset / SMALLOC_BPL;
 	idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;

 	fio_sem_down(pool->lock);
 	clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
 	if (i < pool->next_non_full)
 		pool->next_non_full = i;
 	pool->free_blocks += size_to_blocks(hdr->size);
 	fio_sem_up(pool->lock);
 }

 void sfree(void *ptr)
 {
 	struct pool *pool = NULL;
 	unsigned int i;

 	if (!ptr)
 		return;

 	for (i = 0; i < nr_pools; i++) {
 		if (ptr_valid(&mp[i], ptr)) {
 			pool = &mp[i];
 			break;
 		}
 	}

 	if (pool) {
 		sfree_pool(pool, ptr);
 		return;
 	}

 	log_err("smalloc: ptr %p not from smalloc pool\n", ptr);
 }

 static unsigned int find_best_index(struct pool *pool)
 {
 	unsigned int i;

 	assert(pool->free_blocks);

 	for (i = pool->next_non_full; pool->bitmap[i] == -1U; i++) {
 		if (i == pool->nr_blocks - 1) {
 			unsigned int j;

 			for (j = 0; j < pool->nr_blocks; j++)
 				if (pool->bitmap[j] != -1U)
 					return j;
 		}
 	}

 	return i;
 }

 static void *__smalloc_pool(struct pool *pool, size_t size)
 {
 	size_t nr_blocks;
 	unsigned int i;
 	unsigned int offset;
 	unsigned int last_idx;
 	void *ret = NULL;

 	fio_sem_down(pool->lock);

 	nr_blocks = size_to_blocks(size);
 	if (nr_blocks > pool->free_blocks)
 		goto fail;

 	pool->next_non_full = find_best_index(pool);

 	last_idx = 0;
 	offset = -1U;
 	i = pool->next_non_full;
 	while (i < pool->nr_blocks) {
 		unsigned int idx;

 		if (pool->bitmap[i] == -1U) {
 			i++;
 			last_idx = 0;
 			continue;
 		}

 		idx = find_next_zero(pool->bitmap[i], last_idx);
 		if (!blocks_free(pool, i, idx, nr_blocks)) {
 			idx += nr_blocks;
 			if (idx < SMALLOC_BPI)
 				last_idx = idx;
 			else {
 				last_idx = 0;
 				while (idx >= SMALLOC_BPI) {
 					i++;
 					idx -= SMALLOC_BPI;
 				}
 			}
 			continue;
 		}
 		set_blocks(pool, i, idx, nr_blocks);
 		offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
 		break;
 	}

 	if (i < pool->nr_blocks) {
 		pool->free_blocks -= nr_blocks;
 		ret = pool->map + offset;
 	}
 fail:
 	fio_sem_up(pool->lock);
 	return ret;
 }

 static size_t size_to_alloc_size(size_t size)
 {
 	size_t alloc_size = size + sizeof(struct block_hdr);

 	/*
 	 * Round to int alignment, so that the postred pointer will
 	 * be naturally aligned as well.
 	 */
 #ifdef SMALLOC_REDZONE
 	alloc_size += sizeof(unsigned int);
 	alloc_size = (alloc_size + int_mask) & ~int_mask;
 #endif

 	return alloc_size;
 }

 static void *smalloc_pool(struct pool *pool, size_t size)
 {
 	size_t alloc_size = size_to_alloc_size(size);
 	void *ptr;

 	ptr = __smalloc_pool(pool, alloc_size);
 	if (ptr) {
 		struct block_hdr *hdr = ptr;

 		hdr->size = alloc_size;
 		fill_redzone(hdr);

 		ptr += sizeof(*hdr);
 		memset(ptr, 0, size);
 	}

 	return ptr;
 }

 static void smalloc_print_bitmap(struct pool *pool)
 {
 	size_t nr_blocks = pool->nr_blocks;
 	unsigned int *bitmap = pool->bitmap;
 	unsigned int i, j;
 	char *buffer;

 	if (!enable_smalloc_debug)
 		return;

 	buffer = malloc(SMALLOC_BPI + 1);
 	if (!buffer)
 		return;
 	buffer[SMALLOC_BPI] = '\0';

 	for (i = 0; i < nr_blocks; i++) {
 		unsigned int line = bitmap[i];

 		/* skip completely full lines */
 		if (line == -1U)
 			continue;

 		for (j = 0; j < SMALLOC_BPI; j++)
 			if ((1 << j) & line)
 				buffer[SMALLOC_BPI-1-j] = '1';
 			else
 				buffer[SMALLOC_BPI-1-j] = '0';

 		log_err("smalloc: bitmap %5u, %s\n", i, buffer);
 	}

 	free(buffer);
 }

 void smalloc_debug(size_t size)
 {
 	unsigned int i;
 	size_t alloc_size = size_to_alloc_size(size);
 	size_t alloc_blocks;

 	alloc_blocks = size_to_blocks(alloc_size);

 	if (size)
 		log_err("smalloc: size = %lu, alloc_size = %lu, blocks = %lu\n",
 			(unsigned long) size, (unsigned long) alloc_size,
 			(unsigned long) alloc_blocks);
 	for (i = 0; i < nr_pools; i++) {
 		log_err("smalloc: pool %u, free/total blocks %u/%u\n", i,
 			(unsigned int) (mp[i].free_blocks),
 			(unsigned int) (mp[i].nr_blocks*sizeof(unsigned int)*8));
 		if (size && mp[i].free_blocks >= alloc_blocks) {
 			void *ptr = smalloc_pool(&mp[i], size);
 			if (ptr) {
 				sfree(ptr);
 				last_pool = i;
 				log_err("smalloc: smalloc_pool %u succeeded\n", i);
 			} else {
 				log_err("smalloc: smalloc_pool %u failed\n", i);
 				log_err("smalloc: next_non_full=%u, nr_blocks=%u\n",
 					(unsigned int) mp[i].next_non_full, (unsigned int) mp[i].nr_blocks);
 				smalloc_print_bitmap(&mp[i]);
 			}
 		}
 	}
 }

 void *smalloc(size_t size)
 {
 	unsigned int i, end_pool;

 	if (size != (unsigned int) size)
 		return NULL;

 	i = last_pool;
 	end_pool = nr_pools;

 	do {
 		for (; i < end_pool; i++) {
 			void *ptr = smalloc_pool(&mp[i], size);

 			if (ptr) {
 				last_pool = i;
 				return ptr;
 			}
 		}
 		if (last_pool) {
 			end_pool = last_pool;
 			last_pool = i = 0;
 			continue;
 		}

 		break;
 	} while (1);

 	log_err("smalloc: OOM. Consider using --alloc-size to increase the "
 		"shared memory available.\n");
 	smalloc_debug(size);
 	return NULL;
 }

 void *scalloc(size_t nmemb, size_t size)
 {
 	return smalloc(nmemb * size);
 }

 char *smalloc_strdup(const char *str)
 {
 	char *ptr = NULL;

 	ptr = smalloc(strlen(str) + 1);
 	if (ptr)
 		strcpy(ptr, str);
 	return ptr;
 }
	/*
	* simple memory allocator, backed by mmap() so that it hands out memory
	* that can be shared across processes and threads
	*/
	#include <sys/mman.h>
	#include <assert.h>
	#include <string.h>

	#include "fio.h"
	#include "fio_sem.h"
	#include "os/os.h"
	#include "smalloc.h"
	#include "log.h"

	#define SMALLOC_REDZONE /* define to detect memory corruption */

	#define SMALLOC_BPB 32 /* block size, bytes-per-bit in bitmap */
	#define SMALLOC_BPI (sizeof(unsigned int) * 8)
	#define SMALLOC_BPL (SMALLOC_BPB * SMALLOC_BPI)

	#define INITIAL_SIZE 1610241024 /* new pool size */
	#define INITIAL_POOLS 8 /* maximum number of pools to setup */

	#define MAX_POOLS 16

	#define SMALLOC_PRE_RED 0xdeadbeefU
	#define SMALLOC_POST_RED 0x5aa55aa5U

	unsigned int smalloc_pool_size = INITIAL_SIZE;
	#ifdef SMALLOC_REDZONE
	static const int int_mask = sizeof(int) - 1;
	#endif

	struct pool {
	struct fio_sem lock; / protects this pool */
	void map; / map of blocks */
	unsigned int bitmap; / blocks free/busy map */
	size_t free_blocks; /* free blocks */
	size_t nr_blocks; /* total blocks */
	size_t next_non_full;
	size_t mmap_size;
	};

	struct block_hdr {
	size_t size;
	#ifdef SMALLOC_REDZONE
	unsigned int prered;
	#endif
	};

	/*
	* This suppresses the voluminous potential bitmap printout when
	* smalloc encounters an OOM error
	*/
	static const bool enable_smalloc_debug = false;

	static struct pool *mp;
	static unsigned int nr_pools;
	static unsigned int last_pool;

	static inline int ptr_valid(struct pool pool, void ptr)
	{
	unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;

	return (ptr >= pool->map) && (ptr < pool->map + pool_size);
	}

	static inline size_t size_to_blocks(size_t size)
	{
	return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
	}

	static int blocks_iter(struct pool *pool, unsigned int pool_idx,
	unsigned int idx, size_t nr_blocks,
	int (func)(unsigned int map, unsigned int mask))
	{

	while (nr_blocks) {
	unsigned int this_blocks, mask;
	unsigned int *map;

	if (pool_idx >= pool->nr_blocks)
	return 0;

	map = &pool->bitmap[pool_idx];

	this_blocks = nr_blocks;
	if (this_blocks + idx > SMALLOC_BPI) {
	this_blocks = SMALLOC_BPI - idx;
	idx = SMALLOC_BPI - this_blocks;
	}

	if (this_blocks == SMALLOC_BPI)
	mask = -1U;
	else
	mask = ((1U << this_blocks) - 1) << idx;

	if (!func(map, mask))
	return 0;

	nr_blocks -= this_blocks;
	idx = 0;
	pool_idx++;
	}

	return 1;
	}

	static int mask_cmp(unsigned int *map, unsigned int mask)
	{
	return !(*map & mask);
	}

	static int mask_clear(unsigned int *map, unsigned int mask)
	{
	assert((*map & mask) == mask);
	*map &= ~mask;
	return 1;
	}

	static int mask_set(unsigned int *map, unsigned int mask)
	{
	assert(!(*map & mask));
	*map \|= mask;
	return 1;
	}

	static int blocks_free(struct pool *pool, unsigned int pool_idx,
	unsigned int idx, size_t nr_blocks)
	{
	return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
	}

	static void set_blocks(struct pool *pool, unsigned int pool_idx,
	unsigned int idx, size_t nr_blocks)
	{
	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
	}

	static void clear_blocks(struct pool *pool, unsigned int pool_idx,
	unsigned int idx, size_t nr_blocks)
	{
	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
	}

	static int find_next_zero(int word, int start)
	{
	assert(word != -1U);
	word >>= start;
	return ffz(word) + start;
	}

	static bool add_pool(struct pool *pool, unsigned int alloc_size)
	{
	int bitmap_blocks;
	int mmap_flags;
	void *ptr;

	if (nr_pools == MAX_POOLS)
	return false;

	#ifdef SMALLOC_REDZONE
	alloc_size += sizeof(unsigned int);
	#endif
	alloc_size += sizeof(struct block_hdr);
	if (alloc_size < INITIAL_SIZE)
	alloc_size = INITIAL_SIZE;

	/* round up to nearest full number of blocks */
	alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
	bitmap_blocks = alloc_size / SMALLOC_BPL;
	alloc_size += bitmap_blocks * sizeof(unsigned int);
	pool->mmap_size = alloc_size;

	pool->nr_blocks = bitmap_blocks;
	pool->free_blocks = bitmap_blocks * SMALLOC_BPI;

	mmap_flags = OS_MAP_ANON;
	#ifdef CONFIG_ESX
	mmap_flags \|= MAP_PRIVATE;
	#else
	mmap_flags \|= MAP_SHARED;
	#endif
	ptr = mmap(NULL, alloc_size, PROT_READ\|PROT_WRITE, mmap_flags, -1, 0);

	if (ptr == MAP_FAILED)
	goto out_fail;

	pool->map = ptr;
	pool->bitmap = (unsigned int )((char ) ptr + (pool->nr_blocks * SMALLOC_BPL));
	memset(pool->bitmap, 0, bitmap_blocks * sizeof(unsigned int));

	pool->lock = fio_sem_init(FIO_SEM_UNLOCKED);
	if (!pool->lock)
	goto out_fail;

	nr_pools++;
	return true;
	out_fail:
	log_err("smalloc: failed adding pool\n");
	if (pool->map)
	munmap(pool->map, pool->mmap_size);
	return false;
	}

	void sinit(void)
	{
	bool ret;
	int i;

	/*
	* sinit() can be called more than once if alloc-size is
	* set. But we want to allocate space for the struct pool
	* instances only once.
	*/
	if (!mp) {
	mp = (struct pool *) mmap(NULL,
	MAX_POOLS * sizeof(struct pool),
	PROT_READ \| PROT_WRITE,
	OS_MAP_ANON \| MAP_SHARED, -1, 0);

	assert(mp != MAP_FAILED);
	}

	for (i = 0; i < INITIAL_POOLS; i++) {
	ret = add_pool(&mp[nr_pools], smalloc_pool_size);
	if (!ret)
	break;
	}

	/*
	* If we added at least one pool, we should be OK for most
	* cases.
	*/
	assert(i);
	}

	static void cleanup_pool(struct pool *pool)
	{
	/*
	* This will also remove the temporary file we used as a backing
	* store, it was already unlinked
	*/
	munmap(pool->map, pool->mmap_size);

	if (pool->lock)
	fio_sem_remove(pool->lock);
	}

	void scleanup(void)
	{
	unsigned int i;

	for (i = 0; i < nr_pools; i++)
	cleanup_pool(&mp[i]);

	munmap(mp, MAX_POOLS * sizeof(struct pool));
	}

	#ifdef SMALLOC_REDZONE
	static void postred_ptr(struct block_hdr hdr)
	{
	uintptr_t ptr;

	ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
	ptr = (uintptr_t) PTR_ALIGN(ptr, int_mask);

	return (void *) ptr;
	}

	static void fill_redzone(struct block_hdr *hdr)
	{
	unsigned int *postred = postred_ptr(hdr);

	hdr->prered = SMALLOC_PRE_RED;
	*postred = SMALLOC_POST_RED;
	}

	static void sfree_check_redzone(struct block_hdr *hdr)
	{
	unsigned int *postred = postred_ptr(hdr);

	if (hdr->prered != SMALLOC_PRE_RED) {
	log_err("smalloc pre redzone destroyed!\n"
	" ptr=%p, prered=%x, expected %x\n",
	hdr+1, hdr->prered, SMALLOC_PRE_RED);
	assert(0);
	}
	if (*postred != SMALLOC_POST_RED) {
	log_err("smalloc post redzone destroyed!\n"
	" ptr=%p, postred=%x, expected %x\n",
	hdr+1, *postred, SMALLOC_POST_RED);
	assert(0);
	}
	}
	#else
	static void fill_redzone(struct block_hdr *hdr)
	{
	}

	static void sfree_check_redzone(struct block_hdr *hdr)
	{
	}
	#endif

	static void sfree_pool(struct pool pool, void ptr)
	{
	struct block_hdr *hdr;
	unsigned int i, idx;
	unsigned long offset;

	if (!ptr)
	return;

	ptr -= sizeof(*hdr);
	hdr = ptr;

	assert(ptr_valid(pool, ptr));

	sfree_check_redzone(hdr);

	offset = ptr - pool->map;
	i = offset / SMALLOC_BPL;
	idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;

	fio_sem_down(pool->lock);
	clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
	if (i < pool->next_non_full)
	pool->next_non_full = i;
	pool->free_blocks += size_to_blocks(hdr->size);
	fio_sem_up(pool->lock);
	}

	void sfree(void *ptr)
	{
	struct pool *pool = NULL;
	unsigned int i;

	if (!ptr)
	return;

	for (i = 0; i < nr_pools; i++) {
	if (ptr_valid(&mp[i], ptr)) {
	pool = &mp[i];
	break;
	}
	}

	if (pool) {
	sfree_pool(pool, ptr);
	return;
	}

	log_err("smalloc: ptr %p not from smalloc pool\n", ptr);
	}

	static unsigned int find_best_index(struct pool *pool)
	{
	unsigned int i;

	assert(pool->free_blocks);

	for (i = pool->next_non_full; pool->bitmap[i] == -1U; i++) {
	if (i == pool->nr_blocks - 1) {
	unsigned int j;

	for (j = 0; j < pool->nr_blocks; j++)
	if (pool->bitmap[j] != -1U)
	return j;
	}
	}

	return i;
	}

	static void __smalloc_pool(struct pool pool, size_t size)
	{
	size_t nr_blocks;
	unsigned int i;
	unsigned int offset;
	unsigned int last_idx;
	void *ret = NULL;

	fio_sem_down(pool->lock);

	nr_blocks = size_to_blocks(size);
	if (nr_blocks > pool->free_blocks)
	goto fail;

	pool->next_non_full = find_best_index(pool);

	last_idx = 0;
	offset = -1U;
	i = pool->next_non_full;
	while (i < pool->nr_blocks) {
	unsigned int idx;

	if (pool->bitmap[i] == -1U) {
	i++;
	last_idx = 0;
	continue;
	}

	idx = find_next_zero(pool->bitmap[i], last_idx);
	if (!blocks_free(pool, i, idx, nr_blocks)) {
	idx += nr_blocks;
	if (idx < SMALLOC_BPI)
	last_idx = idx;
	else {
	last_idx = 0;
	while (idx >= SMALLOC_BPI) {
	i++;
	idx -= SMALLOC_BPI;
	}
	}
	continue;
	}
	set_blocks(pool, i, idx, nr_blocks);
	offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
	break;
	}

	if (i < pool->nr_blocks) {
	pool->free_blocks -= nr_blocks;
	ret = pool->map + offset;
	}
	fail:
	fio_sem_up(pool->lock);
	return ret;
	}

	static size_t size_to_alloc_size(size_t size)
	{
	size_t alloc_size = size + sizeof(struct block_hdr);

	/*
	* Round to int alignment, so that the postred pointer will
	* be naturally aligned as well.
	*/
	#ifdef SMALLOC_REDZONE
	alloc_size += sizeof(unsigned int);
	alloc_size = (alloc_size + int_mask) & ~int_mask;
	#endif

	return alloc_size;
	}

	static void smalloc_pool(struct pool pool, size_t size)
	{
	size_t alloc_size = size_to_alloc_size(size);
	void *ptr;

	ptr = __smalloc_pool(pool, alloc_size);
	if (ptr) {
	struct block_hdr *hdr = ptr;

	hdr->size = alloc_size;
	fill_redzone(hdr);

	ptr += sizeof(*hdr);
	memset(ptr, 0, size);
	}

	return ptr;
	}

	static void smalloc_print_bitmap(struct pool *pool)
	{
	size_t nr_blocks = pool->nr_blocks;
	unsigned int *bitmap = pool->bitmap;
	unsigned int i, j;
	char *buffer;

	if (!enable_smalloc_debug)
	return;

	buffer = malloc(SMALLOC_BPI + 1);
	if (!buffer)
	return;
	buffer[SMALLOC_BPI] = '\0';

	for (i = 0; i < nr_blocks; i++) {
	unsigned int line = bitmap[i];

	/* skip completely full lines */
	if (line == -1U)
	continue;

	for (j = 0; j < SMALLOC_BPI; j++)
	if ((1 << j) & line)
	buffer[SMALLOC_BPI-1-j] = '1';
	else
	buffer[SMALLOC_BPI-1-j] = '0';

	log_err("smalloc: bitmap %5u, %s\n", i, buffer);
	}

	free(buffer);
	}

	void smalloc_debug(size_t size)
	{
	unsigned int i;
	size_t alloc_size = size_to_alloc_size(size);
	size_t alloc_blocks;

	alloc_blocks = size_to_blocks(alloc_size);

	if (size)
	log_err("smalloc: size = %lu, alloc_size = %lu, blocks = %lu\n",
	(unsigned long) size, (unsigned long) alloc_size,
	(unsigned long) alloc_blocks);
	for (i = 0; i < nr_pools; i++) {
	log_err("smalloc: pool %u, free/total blocks %u/%u\n", i,
	(unsigned int) (mp[i].free_blocks),
	(unsigned int) (mp[i].nr_blockssizeof(unsigned int)8));
	if (size && mp[i].free_blocks >= alloc_blocks) {
	void *ptr = smalloc_pool(&mp[i], size);
	if (ptr) {
	sfree(ptr);
	last_pool = i;
	log_err("smalloc: smalloc_pool %u succeeded\n", i);
	} else {
	log_err("smalloc: smalloc_pool %u failed\n", i);
	log_err("smalloc: next_non_full=%u, nr_blocks=%u\n",
	(unsigned int) mp[i].next_non_full, (unsigned int) mp[i].nr_blocks);
	smalloc_print_bitmap(&mp[i]);
	}
	}
	}
	}

	void *smalloc(size_t size)
	{
	unsigned int i, end_pool;

	if (size != (unsigned int) size)
	return NULL;

	i = last_pool;
	end_pool = nr_pools;

	do {
	for (; i < end_pool; i++) {
	void *ptr = smalloc_pool(&mp[i], size);

	if (ptr) {
	last_pool = i;
	return ptr;
	}
	}
	if (last_pool) {
	end_pool = last_pool;
	last_pool = i = 0;
	continue;
	}

	break;
	} while (1);

	log_err("smalloc: OOM. Consider using --alloc-size to increase the "
	"shared memory available.\n");
	smalloc_debug(size);
	return NULL;
	}

	void *scalloc(size_t nmemb, size_t size)
	{
	return smalloc(nmemb * size);
	}

	char smalloc_strdup(const char str)
	{
	char *ptr = NULL;

	ptr = smalloc(strlen(str) + 1);
	if (ptr)
	strcpy(ptr, str);
	return ptr;
	}