[fio.git] / smalloc.c

/*
 * 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 <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>
#include <sys/types.h>
#include <limits.h>
#include <fcntl.h>

#include "fio.h"
#include "mutex.h"
#include "arch/arch.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_mutex *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
};

static struct pool mp[MAX_POOLS];
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_BPB;

	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_mutex_init(FIO_MUTEX_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;

	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_mutex_remove(pool->lock);
}

void scleanup(void)
{
	unsigned int i;

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

#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, 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, *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_mutex_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_mutex_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 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_mutex_down(pool->lock);

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

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

		if (pool->bitmap[i] == -1U) {
			i++;
			pool->next_non_full = 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_mutex_up(pool->lock);
	return ret;
}

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

	/*
	 * 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

	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;
}

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");
	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;
}
Commit	Line	Data
	1	/*
	2	* simple memory allocator, backed by mmap() so that it hands out memory
	3	* that can be shared across processes and threads
	4	*/
	5	#include <sys/mman.h>
	6	#include <stdio.h>
	7	#include <stdlib.h>
	8	#include <assert.h>
	9	#include <string.h>
	10	#include <unistd.h>
	11	#include <inttypes.h>
	12	#include <sys/types.h>
	13	#include <limits.h>
	14	#include <fcntl.h>
	15
	16	#include "fio.h"
	17	#include "mutex.h"
	18	#include "arch/arch.h"
	19	#include "os/os.h"
	20	#include "smalloc.h"
	21	#include "log.h"
	22
	23	#define SMALLOC_REDZONE /* define to detect memory corruption */
	24
	25	#define SMALLOC_BPB 32 /* block size, bytes-per-bit in bitmap */
	26	#define SMALLOC_BPI (sizeof(unsigned int) * 8)
	27	#define SMALLOC_BPL (SMALLOC_BPB * SMALLOC_BPI)
	28
	29	#define INITIAL_SIZE 1610241024 /* new pool size */
	30	#define INITIAL_POOLS 8 /* maximum number of pools to setup */
	31
	32	#define MAX_POOLS 16
	33
	34	#define SMALLOC_PRE_RED 0xdeadbeefU
	35	#define SMALLOC_POST_RED 0x5aa55aa5U
	36
	37	unsigned int smalloc_pool_size = INITIAL_SIZE;
	38	#ifdef SMALLOC_REDZONE
	39	static const int int_mask = sizeof(int) - 1;
	40	#endif
	41
	42	struct pool {
	43	struct fio_mutex lock; / protects this pool */
	44	void map; / map of blocks */
	45	unsigned int bitmap; / blocks free/busy map */
	46	size_t free_blocks; /* free blocks */
	47	size_t nr_blocks; /* total blocks */
	48	size_t next_non_full;
	49	size_t mmap_size;
	50	};
	51
	52	struct block_hdr {
	53	size_t size;
	54	#ifdef SMALLOC_REDZONE
	55	unsigned int prered;
	56	#endif
	57	};
	58
	59	static struct pool mp[MAX_POOLS];
	60	static unsigned int nr_pools;
	61	static unsigned int last_pool;
	62
	63	static inline int ptr_valid(struct pool pool, void ptr)
	64	{
	65	unsigned int pool_size = pool->nr_blocks * SMALLOC_BPL;
	66
	67	return (ptr >= pool->map) && (ptr < pool->map + pool_size);
	68	}
	69
	70	static inline size_t size_to_blocks(size_t size)
	71	{
	72	return (size + SMALLOC_BPB - 1) / SMALLOC_BPB;
	73	}
	74
	75	static int blocks_iter(struct pool *pool, unsigned int pool_idx,
	76	unsigned int idx, size_t nr_blocks,
	77	int (func)(unsigned int map, unsigned int mask))
	78	{
	79
	80	while (nr_blocks) {
	81	unsigned int this_blocks, mask;
	82	unsigned int *map;
	83
	84	if (pool_idx >= pool->nr_blocks)
	85	return 0;
	86
	87	map = &pool->bitmap[pool_idx];
	88
	89	this_blocks = nr_blocks;
	90	if (this_blocks + idx > SMALLOC_BPI) {
	91	this_blocks = SMALLOC_BPI - idx;
	92	idx = SMALLOC_BPI - this_blocks;
	93	}
	94
	95	if (this_blocks == SMALLOC_BPI)
	96	mask = -1U;
	97	else
	98	mask = ((1U << this_blocks) - 1) << idx;
	99
	100	if (!func(map, mask))
	101	return 0;
	102
	103	nr_blocks -= this_blocks;
	104	idx = 0;
	105	pool_idx++;
	106	}
	107
	108	return 1;
	109	}
	110
	111	static int mask_cmp(unsigned int *map, unsigned int mask)
	112	{
	113	return !(*map & mask);
	114	}
	115
	116	static int mask_clear(unsigned int *map, unsigned int mask)
	117	{
	118	assert((*map & mask) == mask);
	119	*map &= ~mask;
	120	return 1;
	121	}
	122
	123	static int mask_set(unsigned int *map, unsigned int mask)
	124	{
	125	assert(!(*map & mask));
	126	*map \|= mask;
	127	return 1;
	128	}
	129
	130	static int blocks_free(struct pool *pool, unsigned int pool_idx,
	131	unsigned int idx, size_t nr_blocks)
	132	{
	133	return blocks_iter(pool, pool_idx, idx, nr_blocks, mask_cmp);
	134	}
	135
	136	static void set_blocks(struct pool *pool, unsigned int pool_idx,
	137	unsigned int idx, size_t nr_blocks)
	138	{
	139	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_set);
	140	}
	141
	142	static void clear_blocks(struct pool *pool, unsigned int pool_idx,
	143	unsigned int idx, size_t nr_blocks)
	144	{
	145	blocks_iter(pool, pool_idx, idx, nr_blocks, mask_clear);
	146	}
	147
	148	static int find_next_zero(int word, int start)
	149	{
	150	assert(word != -1U);
	151	word >>= start;
	152	return ffz(word) + start;
	153	}
	154
	155	static bool add_pool(struct pool *pool, unsigned int alloc_size)
	156	{
	157	int bitmap_blocks;
	158	int mmap_flags;
	159	void *ptr;
	160
	161	if (nr_pools == MAX_POOLS)
	162	return false;
	163
	164	#ifdef SMALLOC_REDZONE
	165	alloc_size += sizeof(unsigned int);
	166	#endif
	167	alloc_size += sizeof(struct block_hdr);
	168	if (alloc_size < INITIAL_SIZE)
	169	alloc_size = INITIAL_SIZE;
	170
	171	/* round up to nearest full number of blocks */
	172	alloc_size = (alloc_size + SMALLOC_BPL - 1) & ~(SMALLOC_BPL - 1);
	173	bitmap_blocks = alloc_size / SMALLOC_BPL;
	174	alloc_size += bitmap_blocks * sizeof(unsigned int);
	175	pool->mmap_size = alloc_size;
	176
	177	pool->nr_blocks = bitmap_blocks;
	178	pool->free_blocks = bitmap_blocks * SMALLOC_BPB;
	179
	180	mmap_flags = OS_MAP_ANON;
	181	#ifdef CONFIG_ESX
	182	mmap_flags \|= MAP_PRIVATE;
	183	#else
	184	mmap_flags \|= MAP_SHARED;
	185	#endif
	186	ptr = mmap(NULL, alloc_size, PROT_READ\|PROT_WRITE, mmap_flags, -1, 0);
	187
	188	if (ptr == MAP_FAILED)
	189	goto out_fail;
	190
	191	pool->map = ptr;
	192	pool->bitmap = (unsigned int )((char ) ptr + (pool->nr_blocks * SMALLOC_BPL));
	193	memset(pool->bitmap, 0, bitmap_blocks * sizeof(unsigned int));
	194
	195	pool->lock = fio_mutex_init(FIO_MUTEX_UNLOCKED);
	196	if (!pool->lock)
	197	goto out_fail;
	198
	199	nr_pools++;
	200	return true;
	201	out_fail:
	202	log_err("smalloc: failed adding pool\n");
	203	if (pool->map)
	204	munmap(pool->map, pool->mmap_size);
	205	return false;
	206	}
	207
	208	void sinit(void)
	209	{
	210	bool ret;
	211	int i;
	212
	213	for (i = 0; i < INITIAL_POOLS; i++) {
	214	ret = add_pool(&mp[nr_pools], smalloc_pool_size);
	215	if (!ret)
	216	break;
	217	}
	218
	219	/*
	220	* If we added at least one pool, we should be OK for most
	221	* cases.
	222	*/
	223	assert(i);
	224	}
	225
	226	static void cleanup_pool(struct pool *pool)
	227	{
	228	/*
	229	* This will also remove the temporary file we used as a backing
	230	* store, it was already unlinked
	231	*/
	232	munmap(pool->map, pool->mmap_size);
	233
	234	if (pool->lock)
	235	fio_mutex_remove(pool->lock);
	236	}
	237
	238	void scleanup(void)
	239	{
	240	unsigned int i;
	241
	242	for (i = 0; i < nr_pools; i++)
	243	cleanup_pool(&mp[i]);
	244	}
	245
	246	#ifdef SMALLOC_REDZONE
	247	static void postred_ptr(struct block_hdr hdr)
	248	{
	249	uintptr_t ptr;
	250
	251	ptr = (uintptr_t) hdr + hdr->size - sizeof(unsigned int);
	252	ptr = (uintptr_t) PTR_ALIGN(ptr, int_mask);
	253
	254	return (void *) ptr;
	255	}
	256
	257	static void fill_redzone(struct block_hdr *hdr)
	258	{
	259	unsigned int *postred = postred_ptr(hdr);
	260
	261	hdr->prered = SMALLOC_PRE_RED;
	262	*postred = SMALLOC_POST_RED;
	263	}
	264
	265	static void sfree_check_redzone(struct block_hdr *hdr)
	266	{
	267	unsigned int *postred = postred_ptr(hdr);
	268
	269	if (hdr->prered != SMALLOC_PRE_RED) {
	270	log_err("smalloc pre redzone destroyed!\n"
	271	" ptr=%p, prered=%x, expected %x\n",
	272	hdr, hdr->prered, SMALLOC_PRE_RED);
	273	assert(0);
	274	}
	275	if (*postred != SMALLOC_POST_RED) {
	276	log_err("smalloc post redzone destroyed!\n"
	277	" ptr=%p, postred=%x, expected %x\n",
	278	hdr, *postred, SMALLOC_POST_RED);
	279	assert(0);
	280	}
	281	}
	282	#else
	283	static void fill_redzone(struct block_hdr *hdr)
	284	{
	285	}
	286
	287	static void sfree_check_redzone(struct block_hdr *hdr)
	288	{
	289	}
	290	#endif
	291
	292	static void sfree_pool(struct pool pool, void ptr)
	293	{
	294	struct block_hdr *hdr;
	295	unsigned int i, idx;
	296	unsigned long offset;
	297
	298	if (!ptr)
	299	return;
	300
	301	ptr -= sizeof(*hdr);
	302	hdr = ptr;
	303
	304	assert(ptr_valid(pool, ptr));
	305
	306	sfree_check_redzone(hdr);
	307
	308	offset = ptr - pool->map;
	309	i = offset / SMALLOC_BPL;
	310	idx = (offset % SMALLOC_BPL) / SMALLOC_BPB;
	311
	312	fio_mutex_down(pool->lock);
	313	clear_blocks(pool, i, idx, size_to_blocks(hdr->size));
	314	if (i < pool->next_non_full)
	315	pool->next_non_full = i;
	316	pool->free_blocks += size_to_blocks(hdr->size);
	317	fio_mutex_up(pool->lock);
	318	}
	319
	320	void sfree(void *ptr)
	321	{
	322	struct pool *pool = NULL;
	323	unsigned int i;
	324
	325	if (!ptr)
	326	return;
	327
	328	for (i = 0; i < nr_pools; i++) {
	329	if (ptr_valid(&mp[i], ptr)) {
	330	pool = &mp[i];
	331	break;
	332	}
	333	}
	334
	335	if (pool) {
	336	sfree_pool(pool, ptr);
	337	return;
	338	}
	339
	340	log_err("smalloc: ptr %p not from smalloc pool\n", ptr);
	341	}
	342
	343	static void __smalloc_pool(struct pool pool, size_t size)
	344	{
	345	size_t nr_blocks;
	346	unsigned int i;
	347	unsigned int offset;
	348	unsigned int last_idx;
	349	void *ret = NULL;
	350
	351	fio_mutex_down(pool->lock);
	352
	353	nr_blocks = size_to_blocks(size);
	354	if (nr_blocks > pool->free_blocks)
	355	goto fail;
	356
	357	i = pool->next_non_full;
	358	last_idx = 0;
	359	offset = -1U;
	360	while (i < pool->nr_blocks) {
	361	unsigned int idx;
	362
	363	if (pool->bitmap[i] == -1U) {
	364	i++;
	365	pool->next_non_full = i;
	366	last_idx = 0;
	367	continue;
	368	}
	369
	370	idx = find_next_zero(pool->bitmap[i], last_idx);
	371	if (!blocks_free(pool, i, idx, nr_blocks)) {
	372	idx += nr_blocks;
	373	if (idx < SMALLOC_BPI)
	374	last_idx = idx;
	375	else {
	376	last_idx = 0;
	377	while (idx >= SMALLOC_BPI) {
	378	i++;
	379	idx -= SMALLOC_BPI;
	380	}
	381	}
	382	continue;
	383	}
	384	set_blocks(pool, i, idx, nr_blocks);
	385	offset = i * SMALLOC_BPL + idx * SMALLOC_BPB;
	386	break;
	387	}
	388
	389	if (i < pool->nr_blocks) {
	390	pool->free_blocks -= nr_blocks;
	391	ret = pool->map + offset;
	392	}
	393	fail:
	394	fio_mutex_up(pool->lock);
	395	return ret;
	396	}
	397
	398	static void smalloc_pool(struct pool pool, size_t size)
	399	{
	400	size_t alloc_size = size + sizeof(struct block_hdr);
	401	void *ptr;
	402
	403	/*
	404	* Round to int alignment, so that the postred pointer will
	405	* be naturally aligned as well.
	406	*/
	407	#ifdef SMALLOC_REDZONE
	408	alloc_size += sizeof(unsigned int);
	409	alloc_size = (alloc_size + int_mask) & ~int_mask;
	410	#endif
	411
	412	ptr = __smalloc_pool(pool, alloc_size);
	413	if (ptr) {
	414	struct block_hdr *hdr = ptr;
	415
	416	hdr->size = alloc_size;
	417	fill_redzone(hdr);
	418
	419	ptr += sizeof(*hdr);
	420	memset(ptr, 0, size);
	421	}
	422
	423	return ptr;
	424	}
	425
	426	void *smalloc(size_t size)
	427	{
	428	unsigned int i, end_pool;
	429
	430	if (size != (unsigned int) size)
	431	return NULL;
	432
	433	i = last_pool;
	434	end_pool = nr_pools;
	435
	436	do {
	437	for (; i < end_pool; i++) {
	438	void *ptr = smalloc_pool(&mp[i], size);
	439
	440	if (ptr) {
	441	last_pool = i;
	442	return ptr;
	443	}
	444	}
	445	if (last_pool) {
	446	end_pool = last_pool;
	447	last_pool = i = 0;
	448	continue;
	449	}
	450
	451	break;
	452	} while (1);
	453
	454	log_err("smalloc: OOM. Consider using --alloc-size to increase the "
	455	"shared memory available.\n");
	456	return NULL;
	457	}
	458
	459	void *scalloc(size_t nmemb, size_t size)
	460	{
	461	return smalloc(nmemb * size);
	462	}
	463
	464	char smalloc_strdup(const char str)
	465	{
	466	char *ptr = NULL;
	467
	468	ptr = smalloc(strlen(str) + 1);
	469	if (ptr)
	470	strcpy(ptr, str);
	471	return ptr;
	472	}