src/zmalloc.c

/* zmalloc - total amount of allocated memory aware version of malloc()
 *
 * Copyright (c) 2009-2010, Salvatore Sanfilippo <antirez at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>

/* This function provide us access to the original libc free(). This is useful
 * for instance to free results obtained by backtrace_symbols(). We need
 * to define this function before including zmalloc.h that may shadow the
 * free implementation if we use jemalloc or another non standard allocator. */
void zlibc_free(void *ptr) {
    free(ptr);
}

#include <string.h>
#include <pthread.h>
#include "config.h"
#include "zmalloc.h"

#ifdef HAVE_MALLOC_SIZE
#define PREFIX_SIZE (0)
#else
#if defined(__sun) || defined(__sparc) || defined(__sparc__)
#define PREFIX_SIZE (sizeof(long long))
#else
#define PREFIX_SIZE (sizeof(size_t))
#endif
#endif

/* Explicitly override malloc/free etc when using tcmalloc. */
#if defined(USE_TCMALLOC)
#define malloc(size) tc_malloc(size)
#define calloc(count,size) tc_calloc(count,size)
#define realloc(ptr,size) tc_realloc(ptr,size)
#define free(ptr) tc_free(ptr)
#elif defined(USE_JEMALLOC)
#define malloc(size) je_malloc(size)
#define calloc(count,size) je_calloc(count,size)
#define realloc(ptr,size) je_realloc(ptr,size)
#define free(ptr) je_free(ptr)
#endif

#ifdef HAVE_ATOMIC
#define update_zmalloc_stat_add(__n) __sync_add_and_fetch(&used_memory, (__n))
#define update_zmalloc_stat_sub(__n) __sync_sub_and_fetch(&used_memory, (__n))
#else
#define update_zmalloc_stat_add(__n) do { \
    pthread_mutex_lock(&used_memory_mutex); \
    used_memory += (__n); \
    pthread_mutex_unlock(&used_memory_mutex); \
} while(0)

#define update_zmalloc_stat_sub(__n) do { \
    pthread_mutex_lock(&used_memory_mutex); \
    used_memory -= (__n); \
    pthread_mutex_unlock(&used_memory_mutex); \
} while(0)

#endif

#define update_zmalloc_stat_alloc(__n,__size) do { \
    size_t _n = (__n); \
    if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
    if (zmalloc_thread_safe) { \
        update_zmalloc_stat_add(_n); \
    } else { \
        used_memory += _n; \
    } \
} while(0)

#define update_zmalloc_stat_free(__n) do { \
    size_t _n = (__n); \
    if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
    if (zmalloc_thread_safe) { \
        update_zmalloc_stat_sub(_n); \
    } else { \
        used_memory -= _n; \
    } \
} while(0)

static size_t used_memory = 0;
static int zmalloc_thread_safe = 0;
pthread_mutex_t used_memory_mutex = PTHREAD_MUTEX_INITIALIZER;

static void zmalloc_default_oom(size_t size) {
    fprintf(stderr, "zmalloc: Out of memory trying to allocate %zu bytes\n",
        size);
    fflush(stderr);
    abort();
}

static void (*zmalloc_oom_handler)(size_t) = zmalloc_default_oom;

void *zmalloc(size_t size) {
    void *ptr = malloc(size+PREFIX_SIZE);

    if (!ptr) zmalloc_oom_handler(size);
#ifdef HAVE_MALLOC_SIZE
    update_zmalloc_stat_alloc(zmalloc_size(ptr),size);
    return ptr;
#else
    *((size_t*)ptr) = size;
    update_zmalloc_stat_alloc(size+PREFIX_SIZE,size);
    return (char*)ptr+PREFIX_SIZE;
#endif
}

void *zcalloc(size_t size) {
    void *ptr = calloc(1, size+PREFIX_SIZE);

    if (!ptr) zmalloc_oom_handler(size);
#ifdef HAVE_MALLOC_SIZE
    update_zmalloc_stat_alloc(zmalloc_size(ptr),size);
    return ptr;
#else
    *((size_t*)ptr) = size;
    update_zmalloc_stat_alloc(size+PREFIX_SIZE,size);
    return (char*)ptr+PREFIX_SIZE;
#endif
}

void *zrealloc(void *ptr, size_t size) {
#ifndef HAVE_MALLOC_SIZE
    void *realptr;
#endif
    size_t oldsize;
    void *newptr;

    if (ptr == NULL) return zmalloc(size);
#ifdef HAVE_MALLOC_SIZE
    oldsize = zmalloc_size(ptr);
    newptr = realloc(ptr,size);
    if (!newptr) zmalloc_oom_handler(size);

    update_zmalloc_stat_free(oldsize);
    update_zmalloc_stat_alloc(zmalloc_size(newptr),size);
    return newptr;
#else
    realptr = (char*)ptr-PREFIX_SIZE;
    oldsize = *((size_t*)realptr);
    newptr = realloc(realptr,size+PREFIX_SIZE);
    if (!newptr) zmalloc_oom_handler(size);

    *((size_t*)newptr) = size;
    update_zmalloc_stat_free(oldsize);
    update_zmalloc_stat_alloc(size,size);
    return (char*)newptr+PREFIX_SIZE;
#endif
}

/* Provide zmalloc_size() for systems where this function is not provided by
 * malloc itself, given that in that case we store an header with this
 * information as the first bytes of every allocation. */
#ifndef HAVE_MALLOC_SIZE
size_t zmalloc_size(void *ptr) {
    void *realptr = (char*)ptr-PREFIX_SIZE;
    size_t size = *((size_t*)realptr);
    /* Assume at least that all the allocations are padded at sizeof(long) by
     * the underlying allocator. */
    if (size&(sizeof(long)-1)) size += sizeof(long)-(size&(sizeof(long)-1));
    return size+PREFIX_SIZE;
}
#endif

void zfree(void *ptr) {
#ifndef HAVE_MALLOC_SIZE
    void *realptr;
    size_t oldsize;
#endif

    if (ptr == NULL) return;
#ifdef HAVE_MALLOC_SIZE
    update_zmalloc_stat_free(zmalloc_size(ptr));
    free(ptr);
#else
    realptr = (char*)ptr-PREFIX_SIZE;
    oldsize = *((size_t*)realptr);
    update_zmalloc_stat_free(oldsize+PREFIX_SIZE);
    free(realptr);
#endif
}

char *zstrdup(const char *s) {
    size_t l = strlen(s)+1;
    char *p = zmalloc(l);

    memcpy(p,s,l);
    return p;
}

size_t zmalloc_used_memory(void) {
    size_t um;

    if (zmalloc_thread_safe) {
#ifdef HAVE_ATOMIC
        um = __sync_add_and_fetch(&used_memory, 0);
#else
        pthread_mutex_lock(&used_memory_mutex);
        um = used_memory;
        pthread_mutex_unlock(&used_memory_mutex);
#endif
    }
    else {
        um = used_memory;
    }

    return um;
}

void zmalloc_enable_thread_safeness(void) {
    zmalloc_thread_safe = 1;
}

void zmalloc_set_oom_handler(void (*oom_handler)(size_t)) {
    zmalloc_oom_handler = oom_handler;
}

/* Get the RSS information in an OS-specific way.
 *
 * WARNING: the function zmalloc_get_rss() is not designed to be fast
 * and may not be called in the busy loops where Redis tries to release
 * memory expiring or swapping out objects.
 *
 * For this kind of "fast RSS reporting" usages use instead the
 * function RedisEstimateRSS() that is a much faster (and less precise)
 * version of the funciton. */

#if defined(HAVE_PROCFS)
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

size_t zmalloc_get_rss(void) {
    int page = sysconf(_SC_PAGESIZE);
    size_t rss;
    char buf[4096];
    char filename[256];
    int fd, count;
    char *p, *x;

    snprintf(filename,256,"/proc/%d/stat",getpid());
    if ((fd = open(filename,O_RDONLY)) == -1) return 0;
    if (read(fd,buf,4096) <= 0) {
        close(fd);
        return 0;
    }
    close(fd);

    p = buf;
    count = 23; /* RSS is the 24th field in /proc/<pid>/stat */
    while(p && count--) {
        p = strchr(p,' ');
        if (p) p++;
    }
    if (!p) return 0;
    x = strchr(p,' ');
    if (!x) return 0;
    *x = '\0';

    rss = strtoll(p,NULL,10);
    rss *= page;
    return rss;
}
#elif defined(HAVE_TASKINFO)
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/sysctl.h>
#include <mach/task.h>
#include <mach/mach_init.h>

size_t zmalloc_get_rss(void) {
    task_t task = MACH_PORT_NULL;
    struct task_basic_info t_info;
    mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;

    if (task_for_pid(current_task(), getpid(), &task) != KERN_SUCCESS)
        return 0;
    task_info(task, TASK_BASIC_INFO, (task_info_t)&t_info, &t_info_count);

    return t_info.resident_size;
}
#else
size_t zmalloc_get_rss(void) {
    /* If we can't get the RSS in an OS-specific way for this system just
     * return the memory usage we estimated in zmalloc()..
     *
     * Fragmentation will appear to be always 1 (no fragmentation)
     * of course... */
    return zmalloc_used_memory();
}
#endif

/* Fragmentation = RSS / allocated-bytes */
float zmalloc_get_fragmentation_ratio(void) {
    return (float)zmalloc_get_rss()/zmalloc_used_memory();
}
Commit	Line	Data
	1	/* zmalloc - total amount of allocated memory aware version of malloc()
	2	*
	3	* Copyright (c) 2009-2010, Salvatore Sanfilippo <antirez at gmail dot com>
	4	* All rights reserved.
	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions are met:
	8	*
	9	* * Redistributions of source code must retain the above copyright notice,
	10	* this list of conditions and the following disclaimer.
	11	* * Redistributions in binary form must reproduce the above copyright
	12	* notice, this list of conditions and the following disclaimer in the
	13	* documentation and/or other materials provided with the distribution.
	14	* * Neither the name of Redis nor the names of its contributors may be used
	15	* to endorse or promote products derived from this software without
	16	* specific prior written permission.
	17	*
	18	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
	19	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	20	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	21	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
	22	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
	23	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
	24	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
	25	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
	26	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	27	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
	28	* POSSIBILITY OF SUCH DAMAGE.
	29	*/
	30
	31	#include <stdio.h>
	32	#include <stdlib.h>
	33
	34	/* This function provide us access to the original libc free(). This is useful
	35	* for instance to free results obtained by backtrace_symbols(). We need
	36	* to define this function before including zmalloc.h that may shadow the
	37	* free implementation if we use jemalloc or another non standard allocator. */
	38	void zlibc_free(void *ptr) {
	39	free(ptr);
	40	}
	41
	42	#include <string.h>
	43	#include <pthread.h>
	44	#include "config.h"
	45	#include "zmalloc.h"
	46
	47	#ifdef HAVE_MALLOC_SIZE
	48	#define PREFIX_SIZE (0)
	49	#else
	50	#if defined(__sun) \|\| defined(__sparc) \|\| defined(__sparc__)
	51	#define PREFIX_SIZE (sizeof(long long))
	52	#else
	53	#define PREFIX_SIZE (sizeof(size_t))
	54	#endif
	55	#endif
	56
	57	/* Explicitly override malloc/free etc when using tcmalloc. */
	58	#if defined(USE_TCMALLOC)
	59	#define malloc(size) tc_malloc(size)
	60	#define calloc(count,size) tc_calloc(count,size)
	61	#define realloc(ptr,size) tc_realloc(ptr,size)
	62	#define free(ptr) tc_free(ptr)
	63	#elif defined(USE_JEMALLOC)
	64	#define malloc(size) je_malloc(size)
	65	#define calloc(count,size) je_calloc(count,size)
	66	#define realloc(ptr,size) je_realloc(ptr,size)
	67	#define free(ptr) je_free(ptr)
	68	#endif
	69
	70	#ifdef HAVE_ATOMIC
	71	#define update_zmalloc_stat_add(__n) __sync_add_and_fetch(&used_memory, (__n))
	72	#define update_zmalloc_stat_sub(__n) __sync_sub_and_fetch(&used_memory, (__n))
	73	#else
	74	#define update_zmalloc_stat_add(__n) do { \
	75	pthread_mutex_lock(&used_memory_mutex); \
	76	used_memory += (__n); \
	77	pthread_mutex_unlock(&used_memory_mutex); \
	78	} while(0)
	79
	80	#define update_zmalloc_stat_sub(__n) do { \
	81	pthread_mutex_lock(&used_memory_mutex); \
	82	used_memory -= (__n); \
	83	pthread_mutex_unlock(&used_memory_mutex); \
	84	} while(0)
	85
	86	#endif
	87
	88	#define update_zmalloc_stat_alloc(__n,__size) do { \
	89	size_t _n = (__n); \
	90	if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
	91	if (zmalloc_thread_safe) { \
	92	update_zmalloc_stat_add(_n); \
	93	} else { \
	94	used_memory += _n; \
	95	} \
	96	} while(0)
	97
	98	#define update_zmalloc_stat_free(__n) do { \
	99	size_t _n = (__n); \
	100	if (_n&(sizeof(long)-1)) _n += sizeof(long)-(_n&(sizeof(long)-1)); \
	101	if (zmalloc_thread_safe) { \
	102	update_zmalloc_stat_sub(_n); \
	103	} else { \
	104	used_memory -= _n; \
	105	} \
	106	} while(0)
	107
	108	static size_t used_memory = 0;
	109	static int zmalloc_thread_safe = 0;
	110	pthread_mutex_t used_memory_mutex = PTHREAD_MUTEX_INITIALIZER;
	111
	112	static void zmalloc_default_oom(size_t size) {
	113	fprintf(stderr, "zmalloc: Out of memory trying to allocate %zu bytes\n",
	114	size);
	115	fflush(stderr);
	116	abort();
	117	}
	118
	119	static void (*zmalloc_oom_handler)(size_t) = zmalloc_default_oom;
	120
	121	void *zmalloc(size_t size) {
	122	void *ptr = malloc(size+PREFIX_SIZE);
	123
	124	if (!ptr) zmalloc_oom_handler(size);
	125	#ifdef HAVE_MALLOC_SIZE
	126	update_zmalloc_stat_alloc(zmalloc_size(ptr),size);
	127	return ptr;
	128	#else
	129	((size_t)ptr) = size;
	130	update_zmalloc_stat_alloc(size+PREFIX_SIZE,size);
	131	return (char*)ptr+PREFIX_SIZE;
	132	#endif
	133	}
	134
	135	void *zcalloc(size_t size) {
	136	void *ptr = calloc(1, size+PREFIX_SIZE);
	137
	138	if (!ptr) zmalloc_oom_handler(size);
	139	#ifdef HAVE_MALLOC_SIZE
	140	update_zmalloc_stat_alloc(zmalloc_size(ptr),size);
	141	return ptr;
	142	#else
	143	((size_t)ptr) = size;
	144	update_zmalloc_stat_alloc(size+PREFIX_SIZE,size);
	145	return (char*)ptr+PREFIX_SIZE;
	146	#endif
	147	}
	148
	149	void zrealloc(void ptr, size_t size) {
	150	#ifndef HAVE_MALLOC_SIZE
	151	void *realptr;
	152	#endif
	153	size_t oldsize;
	154	void *newptr;
	155
	156	if (ptr == NULL) return zmalloc(size);
	157	#ifdef HAVE_MALLOC_SIZE
	158	oldsize = zmalloc_size(ptr);
	159	newptr = realloc(ptr,size);
	160	if (!newptr) zmalloc_oom_handler(size);
	161
	162	update_zmalloc_stat_free(oldsize);
	163	update_zmalloc_stat_alloc(zmalloc_size(newptr),size);
	164	return newptr;
	165	#else
	166	realptr = (char*)ptr-PREFIX_SIZE;
	167	oldsize = ((size_t)realptr);
	168	newptr = realloc(realptr,size+PREFIX_SIZE);
	169	if (!newptr) zmalloc_oom_handler(size);
	170
	171	((size_t)newptr) = size;
	172	update_zmalloc_stat_free(oldsize);
	173	update_zmalloc_stat_alloc(size,size);
	174	return (char*)newptr+PREFIX_SIZE;
	175	#endif
	176	}
	177
	178	/* Provide zmalloc_size() for systems where this function is not provided by
	179	* malloc itself, given that in that case we store an header with this
	180	* information as the first bytes of every allocation. */
	181	#ifndef HAVE_MALLOC_SIZE
	182	size_t zmalloc_size(void *ptr) {
	183	void realptr = (char)ptr-PREFIX_SIZE;
	184	size_t size = ((size_t)realptr);
	185	/* Assume at least that all the allocations are padded at sizeof(long) by
	186	* the underlying allocator. */
	187	if (size&(sizeof(long)-1)) size += sizeof(long)-(size&(sizeof(long)-1));
	188	return size+PREFIX_SIZE;
	189	}
	190	#endif
	191
	192	void zfree(void *ptr) {
	193	#ifndef HAVE_MALLOC_SIZE
	194	void *realptr;
	195	size_t oldsize;
	196	#endif
	197
	198	if (ptr == NULL) return;
	199	#ifdef HAVE_MALLOC_SIZE
	200	update_zmalloc_stat_free(zmalloc_size(ptr));
	201	free(ptr);
	202	#else
	203	realptr = (char*)ptr-PREFIX_SIZE;
	204	oldsize = ((size_t)realptr);
	205	update_zmalloc_stat_free(oldsize+PREFIX_SIZE);
	206	free(realptr);
	207	#endif
	208	}
	209
	210	char zstrdup(const char s) {
	211	size_t l = strlen(s)+1;
	212	char *p = zmalloc(l);
	213
	214	memcpy(p,s,l);
	215	return p;
	216	}
	217
	218	size_t zmalloc_used_memory(void) {
	219	size_t um;
	220
	221	if (zmalloc_thread_safe) {
	222	#ifdef HAVE_ATOMIC
	223	um = __sync_add_and_fetch(&used_memory, 0);
	224	#else
	225	pthread_mutex_lock(&used_memory_mutex);
	226	um = used_memory;
	227	pthread_mutex_unlock(&used_memory_mutex);
	228	#endif
	229	}
	230	else {
	231	um = used_memory;
	232	}
	233
	234	return um;
	235	}
	236
	237	void zmalloc_enable_thread_safeness(void) {
	238	zmalloc_thread_safe = 1;
	239	}
	240
	241	void zmalloc_set_oom_handler(void (*oom_handler)(size_t)) {
	242	zmalloc_oom_handler = oom_handler;
	243	}
	244
	245	/* Get the RSS information in an OS-specific way.
	246	*
	247	* WARNING: the function zmalloc_get_rss() is not designed to be fast
	248	* and may not be called in the busy loops where Redis tries to release
	249	* memory expiring or swapping out objects.
	250	*
	251	* For this kind of "fast RSS reporting" usages use instead the
	252	* function RedisEstimateRSS() that is a much faster (and less precise)
	253	* version of the funciton. */
	254
	255	#if defined(HAVE_PROCFS)
	256	#include <unistd.h>
	257	#include <sys/types.h>
	258	#include <sys/stat.h>
	259	#include <fcntl.h>
	260
	261	size_t zmalloc_get_rss(void) {
	262	int page = sysconf(_SC_PAGESIZE);
	263	size_t rss;
	264	char buf[4096];
	265	char filename[256];
	266	int fd, count;
	267	char p, x;
	268
	269	snprintf(filename,256,"/proc/%d/stat",getpid());
	270	if ((fd = open(filename,O_RDONLY)) == -1) return 0;
	271	if (read(fd,buf,4096) <= 0) {
	272	close(fd);
	273	return 0;
	274	}
	275	close(fd);
	276
	277	p = buf;
	278	count = 23; /* RSS is the 24th field in /proc/<pid>/stat */
	279	while(p && count--) {
	280	p = strchr(p,' ');
	281	if (p) p++;
	282	}
	283	if (!p) return 0;
	284	x = strchr(p,' ');
	285	if (!x) return 0;
	286	*x = '\0';
	287
	288	rss = strtoll(p,NULL,10);
	289	rss *= page;
	290	return rss;
	291	}
	292	#elif defined(HAVE_TASKINFO)
	293	#include <unistd.h>
	294	#include <stdio.h>
	295	#include <stdlib.h>
	296	#include <sys/types.h>
	297	#include <sys/sysctl.h>
	298	#include <mach/task.h>
	299	#include <mach/mach_init.h>
	300
	301	size_t zmalloc_get_rss(void) {
	302	task_t task = MACH_PORT_NULL;
	303	struct task_basic_info t_info;
	304	mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;
	305
	306	if (task_for_pid(current_task(), getpid(), &task) != KERN_SUCCESS)
	307	return 0;
	308	task_info(task, TASK_BASIC_INFO, (task_info_t)&t_info, &t_info_count);
	309
	310	return t_info.resident_size;
	311	}
	312	#else
	313	size_t zmalloc_get_rss(void) {
	314	/* If we can't get the RSS in an OS-specific way for this system just
	315	* return the memory usage we estimated in zmalloc()..
	316	*
	317	* Fragmentation will appear to be always 1 (no fragmentation)
	318	* of course... */
	319	return zmalloc_used_memory();
	320	}
	321	#endif
	322
	323	/* Fragmentation = RSS / allocated-bytes */
	324	float zmalloc_get_fragmentation_ratio(void) {
	325	return (float)zmalloc_get_rss()/zmalloc_used_memory();
	326	}