3 .\" Author: Jason Evans
4 .\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
6 .\" Manual: User Manual
7 .\" Source: jemalloc 3.5.1-0-g7709a64c59daf0b1f938be49472fcc499e1bd136
10 .TH "JEMALLOC" "3" "02/25/2014" "jemalloc 3.5.1-0-g7709a64c59da" "User Manual"
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16 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
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31 jemalloc \- general purpose memory allocation functions
34 This manual describes jemalloc 3\&.5\&.1\-0\-g7709a64c59daf0b1f938be49472fcc499e1bd136\&. More information can be found at the
35 \m[blue]\fBjemalloc website\fR\m[]\&\s-2\u[1]\d\s+2\&.
37 The following configuration options are enabled in libc\*(Aqs built\-in jemalloc:
38 \fB\-\-enable\-dss\fR,
39 \fB\-\-enable\-experimental\fR,
40 \fB\-\-enable\-fill\fR,
41 \fB\-\-enable\-lazy\-lock\fR,
42 \fB\-\-enable\-munmap\fR,
43 \fB\-\-enable\-stats\fR,
44 \fB\-\-enable\-tcache\fR,
45 \fB\-\-enable\-tls\fR,
46 \fB\-\-enable\-utrace\fR, and
47 \fB\-\-enable\-xmalloc\fR\&. Additionally,
48 \fB\-\-enable\-debug\fR
49 is enabled in development versions of FreeBSD (controlled by the
50 \fBMALLOC_PRODUCTION\fR
57 #include <malloc_np\&.h>
61 .HP \w'void\ *malloc('u
62 .BI "void *malloc(size_t\ " "size" ");"
63 .HP \w'void\ *calloc('u
64 .BI "void *calloc(size_t\ " "number" ", size_t\ " "size" ");"
65 .HP \w'int\ posix_memalign('u
66 .BI "int posix_memalign(void\ **" "ptr" ", size_t\ " "alignment" ", size_t\ " "size" ");"
67 .HP \w'void\ *aligned_alloc('u
68 .BI "void *aligned_alloc(size_t\ " "alignment" ", size_t\ " "size" ");"
69 .HP \w'void\ *realloc('u
70 .BI "void *realloc(void\ *" "ptr" ", size_t\ " "size" ");"
72 .BI "void free(void\ *" "ptr" ");"
73 .SS "Non\-standard API"
74 .HP \w'void\ *mallocx('u
75 .BI "void *mallocx(size_t\ " "size" ", int\ " "flags" ");"
76 .HP \w'void\ *rallocx('u
77 .BI "void *rallocx(void\ *" "ptr" ", size_t\ " "size" ", int\ " "flags" ");"
78 .HP \w'size_t\ xallocx('u
79 .BI "size_t xallocx(void\ *" "ptr" ", size_t\ " "size" ", size_t\ " "extra" ", int\ " "flags" ");"
80 .HP \w'size_t\ sallocx('u
81 .BI "size_t sallocx(void\ *" "ptr" ", int\ " "flags" ");"
82 .HP \w'void\ dallocx('u
83 .BI "void dallocx(void\ *" "ptr" ", int\ " "flags" ");"
84 .HP \w'size_t\ nallocx('u
85 .BI "size_t nallocx(size_t\ " "size" ", int\ " "flags" ");"
86 .HP \w'int\ mallctl('u
87 .BI "int mallctl(const\ char\ *" "name" ", void\ *" "oldp" ", size_t\ *" "oldlenp" ", void\ *" "newp" ", size_t\ " "newlen" ");"
88 .HP \w'int\ mallctlnametomib('u
89 .BI "int mallctlnametomib(const\ char\ *" "name" ", size_t\ *" "mibp" ", size_t\ *" "miblenp" ");"
90 .HP \w'int\ mallctlbymib('u
91 .BI "int mallctlbymib(const\ size_t\ *" "mib" ", size_t\ " "miblen" ", void\ *" "oldp" ", size_t\ *" "oldlenp" ", void\ *" "newp" ", size_t\ " "newlen" ");"
92 .HP \w'void\ malloc_stats_print('u
93 .BI "void malloc_stats_print(void\ " "(*write_cb)" "\ (void\ *,\ const\ char\ *), void\ *" "cbopaque" ", const\ char\ *" "opts" ");"
94 .HP \w'size_t\ malloc_usable_size('u
95 .BI "size_t malloc_usable_size(const\ void\ *" "ptr" ");"
96 .HP \w'void\ (*malloc_message)('u
97 .BI "void (*malloc_message)(void\ *" "cbopaque" ", const\ char\ *" "s" ");"
99 const char *\fImalloc_conf\fR;
100 .SS "Experimental API"
101 .HP \w'int\ allocm('u
102 .BI "int allocm(void\ **" "ptr" ", size_t\ *" "rsize" ", size_t\ " "size" ", int\ " "flags" ");"
103 .HP \w'int\ rallocm('u
104 .BI "int rallocm(void\ **" "ptr" ", size_t\ *" "rsize" ", size_t\ " "size" ", size_t\ " "extra" ", int\ " "flags" ");"
105 .HP \w'int\ sallocm('u
106 .BI "int sallocm(const\ void\ *" "ptr" ", size_t\ *" "rsize" ", int\ " "flags" ");"
107 .HP \w'int\ dallocm('u
108 .BI "int dallocm(void\ *" "ptr" ", int\ " "flags" ");"
109 .HP \w'int\ nallocm('u
110 .BI "int nallocm(size_t\ *" "rsize" ", size_t\ " "size" ", int\ " "flags" ");"
118 bytes of uninitialized memory\&. The allocated space is suitably aligned (after possible pointer coercion) for storage of any type of object\&.
122 function allocates space for
126 bytes in length\&. The result is identical to calling
131 \fIsize\fR, with the exception that the allocated memory is explicitly initialized to zero bytes\&.
134 \fBposix_memalign\fR\fB\fR
137 bytes of memory such that the allocation\*(Aqs base address is an even multiple of
138 \fIalignment\fR, and returns the allocation in the value pointed to by
139 \fIptr\fR\&. The requested
141 must be a power of 2 at least as large as
142 sizeof(\fBvoid *\fR)\&.
145 \fBaligned_alloc\fR\fB\fR
148 bytes of memory such that the allocation\*(Aqs base address is an even multiple of
149 \fIalignment\fR\&. The requested
151 must be a power of 2\&. Behavior is undefined if
153 is not an integral multiple of
158 function changes the size of the previously allocated memory referenced by
162 bytes\&. The contents of the memory are unchanged up to the lesser of the new and old sizes\&. If the new size is larger, the contents of the newly allocated portion of the memory are undefined\&. Upon success, the memory referenced by
164 is freed and a pointer to the newly allocated memory is returned\&. Note that
166 may move the memory allocation, resulting in a different return value than
172 function behaves identically to
174 for the specified size\&.
178 function causes the allocated memory referenced by
180 to be made available for future allocations\&. If
183 \fBNULL\fR, no action occurs\&.
184 .SS "Non\-standard API"
191 \fBdallocx\fR\fB\fR, and
195 argument that can be used to specify options\&. The functions only check the options that are contextually relevant\&. Use bitwise or (|) operations to specify one or more of the following:
197 \fBMALLOCX_LG_ALIGN(\fR\fB\fIla\fR\fR\fB) \fR
199 Align the memory allocation to start at an address that is a multiple of
200 (1 << \fIla\fR)\&. This macro does not validate that
202 is within the valid range\&.
205 \fBMALLOCX_ALIGN(\fR\fB\fIa\fR\fR\fB) \fR
207 Align the memory allocation to start at an address that is a multiple of
210 is a power of two\&. This macro does not validate that
217 Initialize newly allocated memory to contain zero bytes\&. In the growing reallocation case, the real size prior to reallocation defines the boundary between untouched bytes and those that are initialized to contain zero bytes\&. If this macro is absent, newly allocated memory is uninitialized\&.
220 \fBMALLOCX_ARENA(\fR\fB\fIa\fR\fR\fB) \fR
222 Use the arena specified by the index
224 (and by necessity bypass the thread cache)\&. This macro has no effect for huge regions, nor for regions that were allocated via an arena other than the one specified\&. This macro does not validate that
226 specifies an arena index in the valid range\&.
231 function allocates at least
233 bytes of memory, and returns a pointer to the base address of the allocation\&. Behavior is undefined if
236 \fB0\fR, or if request size overflows due to size class and/or alignment constraints\&.
240 function resizes the allocation at
244 bytes, and returns a pointer to the base address of the resulting allocation, which may or may not have moved from its original location\&. Behavior is undefined if
247 \fB0\fR, or if request size overflows due to size class and/or alignment constraints\&.
251 function resizes the allocation at
253 in place to be at least
255 bytes, and returns the real size of the allocation\&. If
257 is non\-zero, an attempt is made to resize the allocation to be at least
258 (\fIsize\fR + \fIextra\fR)
259 bytes, though inability to allocate the extra byte(s) will not by itself result in failure to resize\&. Behavior is undefined if
263 (\fIsize\fR + \fIextra\fR > \fBSIZE_T_MAX\fR)\&.
267 function returns the real size of the allocation at
272 function causes the memory referenced by
274 to be made available for future allocations\&.
278 function allocates no memory, but it performs the same size computation as the
280 function, and returns the real size of the allocation that would result from the equivalent
282 function call\&. Behavior is undefined if
285 \fB0\fR, or if request size overflows due to size class and/or alignment constraints\&.
289 function provides a general interface for introspecting the memory allocator, as well as setting modifiable parameters and triggering actions\&. The period\-separated
291 argument specifies a location in a tree\-structured namespace; see the
293 section for documentation on the tree contents\&. To read a value, pass a pointer via
295 to adequate space to contain the value, and a pointer to its length via
296 \fIoldlenp\fR; otherwise pass
299 \fBNULL\fR\&. Similarly, to write a value, pass a pointer to the value via
300 \fInewp\fR, and its length via
301 \fInewlen\fR; otherwise pass
307 \fBmallctlnametomib\fR\fB\fR
308 function provides a way to avoid repeated name lookups for applications that repeatedly query the same portion of the namespace, by translating a name to a \(lqManagement Information Base\(rq (MIB) that can be passed repeatedly to
309 \fBmallctlbymib\fR\fB\fR\&. Upon successful return from
310 \fBmallctlnametomib\fR\fB\fR,
316 is the lesser of the number of components in
318 and the input value of
319 \fI*miblenp\fR\&. Thus it is possible to pass a
321 that is smaller than the number of period\-separated name components, which results in a partial MIB that can be used as the basis for constructing a complete MIB\&. For name components that are integers (e\&.g\&. the 2 in
322 "arenas\&.bin\&.2\&.size"), the corresponding MIB component will always be that integer\&. Therefore, it is legitimate to construct code like the following:
333 mallctl("arenas\&.nbins", &nbins, &len, NULL, 0);
336 mallctlnametomib("arenas\&.bin\&.0\&.size", mib, &miblen);
337 for (i = 0; i < nbins; i++) {
341 len = sizeof(bin_size);
342 mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0);
343 /* Do something with bin_size\&.\&.\&. */
351 \fBmalloc_stats_print\fR\fB\fR
352 function writes human\-readable summary statistics via the
354 callback function pointer and
358 \fBmalloc_message\fR\fB\fR
362 \fBNULL\fR\&. This function can be called repeatedly\&. General information that never changes during execution can be omitted by specifying "g" as a character within the
365 \fBmalloc_message\fR\fB\fR
368 functions internally, so inconsistent statistics can be reported if multiple threads use these functions simultaneously\&. If
369 \fB\-\-enable\-stats\fR
370 is specified during configuration, \(lqm\(rq and \(lqa\(rq can be specified to omit merged arena and per arena statistics, respectively; \(lqb\(rq and \(lql\(rq can be specified to omit per size class statistics for bins and large objects, respectively\&. Unrecognized characters are silently ignored\&. Note that thread caching may prevent some statistics from being completely up to date, since extra locking would be required to merge counters that track thread cache operations\&.
373 \fBmalloc_usable_size\fR\fB\fR
374 function returns the usable size of the allocation pointed to by
375 \fIptr\fR\&. The return value may be larger than the size that was requested during allocation\&. The
376 \fBmalloc_usable_size\fR\fB\fR
377 function is not a mechanism for in\-place
378 \fBrealloc\fR\fB\fR; rather it is provided solely as a tool for introspection purposes\&. Any discrepancy between the requested allocation size and the size reported by
379 \fBmalloc_usable_size\fR\fB\fR
380 should not be depended on, since such behavior is entirely implementation\-dependent\&.
381 .SS "Experimental API"
383 The experimental API is subject to change or removal without regard for backward compatibility\&. If
384 \fB\-\-disable\-experimental\fR
385 is specified during configuration, the experimental API is omitted\&.
391 \fBdallocm\fR\fB\fR, and
395 argument that can be used to specify options\&. The functions only check the options that are contextually relevant\&. Use bitwise or (|) operations to specify one or more of the following:
397 \fBALLOCM_LG_ALIGN(\fR\fB\fIla\fR\fR\fB) \fR
399 Align the memory allocation to start at an address that is a multiple of
400 (1 << \fIla\fR)\&. This macro does not validate that
402 is within the valid range\&.
405 \fBALLOCM_ALIGN(\fR\fB\fIa\fR\fR\fB) \fR
407 Align the memory allocation to start at an address that is a multiple of
410 is a power of two\&. This macro does not validate that
417 Initialize newly allocated memory to contain zero bytes\&. In the growing reallocation case, the real size prior to reallocation defines the boundary between untouched bytes and those that are initialized to contain zero bytes\&. If this macro is absent, newly allocated memory is uninitialized\&.
422 For reallocation, fail rather than moving the object\&. This constraint can apply to both growth and shrinkage\&.
425 \fBALLOCM_ARENA(\fR\fB\fIa\fR\fR\fB) \fR
427 Use the arena specified by the index
429 (and by necessity bypass the thread cache)\&. This macro has no effect for huge regions, nor for regions that were allocated via an arena other than the one specified\&. This macro does not validate that
431 specifies an arena index in the valid range\&.
436 function allocates at least
438 bytes of memory, sets
440 to the base address of the allocation, and sets
442 to the real size of the allocation if
445 \fBNULL\fR\&. Behavior is undefined if
448 \fB0\fR, or if request size overflows due to size class and/or alignment constraints\&.
452 function resizes the allocation at
458 to the base address of the allocation if it moved, and sets
460 to the real size of the allocation if
465 is non\-zero, an attempt is made to resize the allocation to be at least
466 (\fIsize\fR + \fIextra\fR)
467 bytes, though inability to allocate the extra byte(s) will not by itself result in failure\&. Behavior is undefined if
470 \fB0\fR, if request size overflows due to size class and/or alignment constraints, or if
471 (\fIsize\fR + \fIextra\fR > \fBSIZE_T_MAX\fR)\&.
477 to the real size of the allocation\&.
481 function causes the memory referenced by
483 to be made available for future allocations\&.
487 function allocates no memory, but it performs the same size computation as the
495 to the real size of the allocation that would result from the equivalent
497 function call\&. Behavior is undefined if
500 \fB0\fR, or if request size overflows due to size class and/or alignment constraints\&.
503 Once, when the first call is made to one of the memory allocation routines, the allocator initializes its internals based in part on various options that can be specified at compile\- or run\-time\&.
505 The string pointed to by the global variable
506 \fImalloc_conf\fR, the \(lqname\(rq of the file referenced by the symbolic link named
507 /etc/malloc\&.conf, and the value of the environment variable
508 \fBMALLOC_CONF\fR, will be interpreted, in that order, from left to right as options\&. Note that
512 is entered, so the declaration of
514 should specify an initializer that contains the final value to be read by jemalloc\&.
516 is a compile\-time setting, whereas
520 can be safely set any time prior to program invocation\&.
522 An options string is a comma\-separated list of option:value pairs\&. There is one key corresponding to each
526 section for options documentation)\&. For example,
532 options\&. Some options have boolean values (true/false), others have integer values (base 8, 10, or 16, depending on prefix), and yet others have raw string values\&.
533 .SH "IMPLEMENTATION NOTES"
535 Traditionally, allocators have used
537 to obtain memory, which is suboptimal for several reasons, including race conditions, increased fragmentation, and artificial limitations on maximum usable memory\&. If
538 \fB\-\-enable\-dss\fR
539 is specified during configuration, this allocator uses both
542 \fBsbrk\fR(2), in that order of preference; otherwise only
546 This allocator uses multiple arenas in order to reduce lock contention for threaded programs on multi\-processor systems\&. This works well with regard to threading scalability, but incurs some costs\&. There is a small fixed per\-arena overhead, and additionally, arenas manage memory completely independently of each other, which means a small fixed increase in overall memory fragmentation\&. These overheads are not generally an issue, given the number of arenas normally used\&. Note that using substantially more arenas than the default is not likely to improve performance, mainly due to reduced cache performance\&. However, it may make sense to reduce the number of arenas if an application does not make much use of the allocation functions\&.
548 In addition to multiple arenas, unless
549 \fB\-\-disable\-tcache\fR
550 is specified during configuration, this allocator supports thread\-specific caching for small and large objects, in order to make it possible to completely avoid synchronization for most allocation requests\&. Such caching allows very fast allocation in the common case, but it increases memory usage and fragmentation, since a bounded number of objects can remain allocated in each thread cache\&.
552 Memory is conceptually broken into equal\-sized chunks, where the chunk size is a power of two that is greater than the page size\&. Chunks are always aligned to multiples of the chunk size\&. This alignment makes it possible to find metadata for user objects very quickly\&.
554 User objects are broken into three categories according to size: small, large, and huge\&. Small objects are smaller than one page\&. Large objects are smaller than the chunk size\&. Huge objects are a multiple of the chunk size\&. Small and large objects are managed by arenas; huge objects are managed separately in a single data structure that is shared by all threads\&. Huge objects are used by applications infrequently enough that this single data structure is not a scalability issue\&.
556 Each chunk that is managed by an arena tracks its contents as runs of contiguous pages (unused, backing a set of small objects, or backing one large object)\&. The combination of chunk alignment and chunk page maps makes it possible to determine all metadata regarding small and large allocations in constant time\&.
558 Small objects are managed in groups by page runs\&. Each run maintains a frontier and free list to track which regions are in use\&. Allocation requests that are no more than half the quantum (8 or 16, depending on architecture) are rounded up to the nearest power of two that is at least
559 sizeof(\fBdouble\fR)\&. All other small object size classes are multiples of the quantum, spaced such that internal fragmentation is limited to approximately 25% for all but the smallest size classes\&. Allocation requests that are larger than the maximum small size class, but small enough to fit in an arena\-managed chunk (see the
561 option), are rounded up to the nearest run size\&. Allocation requests that are too large to fit in an arena\-managed chunk are rounded up to the nearest multiple of the chunk size\&.
563 Allocations are packed tightly together, which can be an issue for multi\-threaded applications\&. If you need to assure that allocations do not suffer from cacheline sharing, round your allocation requests up to the nearest multiple of the cacheline size, or specify cacheline alignment when allocating\&.
565 Assuming 4 MiB chunks, 4 KiB pages, and a 16\-byte quantum on a 64\-bit system, the size classes in each category are as shown in
569 .nr an-no-space-flag 1
572 .B Table\ \&1.\ \&Size classes
603 [16, 32, 48, \&.\&.\&., 128]
618 [640, 768, 896, 1024]
623 [1280, 1536, 1792, 2048]
635 [4 KiB, 8 KiB, 12 KiB, \&.\&.\&., 4072 KiB]
642 [4 MiB, 8 MiB, 12 MiB, \&.\&.\&.]
646 .SH "MALLCTL NAMESPACE"
648 The following names are defined in the namespace accessible via the
650 functions\&. Value types are specified in parentheses, their readable/writable statuses are encoded as
654 \-\-, and required build configuration flags follow, if any\&. A name element encoded as
658 indicates an integer component, where the integer varies from 0 to some upper value that must be determined via introspection\&. In the case of
659 "stats\&.arenas\&.<i>\&.*",
663 can be used to access the summation of statistics from all arenas\&. Take special note of the
665 mallctl, which controls refreshing of cached dynamic statistics\&.
667 "version" (\fBconst char *\fR) r\-
669 Return the jemalloc version string\&.
672 "epoch" (\fBuint64_t\fR) rw
674 If a value is passed in, refresh the data from which the
676 functions report values, and increment the epoch\&. Return the current epoch\&. This is useful for detecting whether another thread caused a refresh\&.
679 "config\&.debug" (\fBbool\fR) r\-
681 \fB\-\-enable\-debug\fR
682 was specified during build configuration\&.
685 "config\&.dss" (\fBbool\fR) r\-
687 \fB\-\-enable\-dss\fR
688 was specified during build configuration\&.
691 "config\&.fill" (\fBbool\fR) r\-
693 \fB\-\-enable\-fill\fR
694 was specified during build configuration\&.
697 "config\&.lazy_lock" (\fBbool\fR) r\-
699 \fB\-\-enable\-lazy\-lock\fR
700 was specified during build configuration\&.
703 "config\&.mremap" (\fBbool\fR) r\-
705 \fB\-\-enable\-mremap\fR
706 was specified during build configuration\&.
709 "config\&.munmap" (\fBbool\fR) r\-
711 \fB\-\-enable\-munmap\fR
712 was specified during build configuration\&.
715 "config\&.prof" (\fBbool\fR) r\-
717 \fB\-\-enable\-prof\fR
718 was specified during build configuration\&.
721 "config\&.prof_libgcc" (\fBbool\fR) r\-
723 \fB\-\-disable\-prof\-libgcc\fR
724 was not specified during build configuration\&.
727 "config\&.prof_libunwind" (\fBbool\fR) r\-
729 \fB\-\-enable\-prof\-libunwind\fR
730 was specified during build configuration\&.
733 "config\&.stats" (\fBbool\fR) r\-
735 \fB\-\-enable\-stats\fR
736 was specified during build configuration\&.
739 "config\&.tcache" (\fBbool\fR) r\-
741 \fB\-\-disable\-tcache\fR
742 was not specified during build configuration\&.
745 "config\&.tls" (\fBbool\fR) r\-
747 \fB\-\-disable\-tls\fR
748 was not specified during build configuration\&.
751 "config\&.utrace" (\fBbool\fR) r\-
753 \fB\-\-enable\-utrace\fR
754 was specified during build configuration\&.
757 "config\&.valgrind" (\fBbool\fR) r\-
759 \fB\-\-enable\-valgrind\fR
760 was specified during build configuration\&.
763 "config\&.xmalloc" (\fBbool\fR) r\-
765 \fB\-\-enable\-xmalloc\fR
766 was specified during build configuration\&.
769 "opt\&.abort" (\fBbool\fR) r\-
771 Abort\-on\-warning enabled/disabled\&. If true, most warnings are fatal\&. The process will call
773 in these cases\&. This option is disabled by default unless
774 \fB\-\-enable\-debug\fR
775 is specified during configuration, in which case it is enabled by default\&.
778 "opt\&.dss" (\fBconst char *\fR) r\-
780 dss (\fBsbrk\fR(2)) allocation precedence as related to
782 allocation\&. The following settings are supported: \(lqdisabled\(rq, \(lqprimary\(rq, and \(lqsecondary\(rq\&. The default is \(lqsecondary\(rq if
784 is true, \(lqdisabled\(rq otherwise\&.
787 "opt\&.lg_chunk" (\fBsize_t\fR) r\-
789 Virtual memory chunk size (log base 2)\&. If a chunk size outside the supported size range is specified, the size is silently clipped to the minimum/maximum supported size\&. The default chunk size is 4 MiB (2^22)\&.
792 "opt\&.narenas" (\fBsize_t\fR) r\-
794 Maximum number of arenas to use for automatic multiplexing of threads and arenas\&. The default is four times the number of CPUs, or one if there is a single CPU\&.
797 "opt\&.lg_dirty_mult" (\fBssize_t\fR) r\-
799 Per\-arena minimum ratio (log base 2) of active to dirty pages\&. Some dirty unused pages may be allowed to accumulate, within the limit set by the ratio (or one chunk worth of dirty pages, whichever is greater), before informing the kernel about some of those pages via
801 or a similar system call\&. This provides the kernel with sufficient information to recycle dirty pages if physical memory becomes scarce and the pages remain unused\&. The default minimum ratio is 8:1 (2^3:1); an option value of \-1 will disable dirty page purging\&.
804 "opt\&.stats_print" (\fBbool\fR) r\-
806 Enable/disable statistics printing at exit\&. If enabled, the
807 \fBmalloc_stats_print\fR\fB\fR
808 function is called at program exit via an
811 \fB\-\-enable\-stats\fR
812 is specified during configuration, this has the potential to cause deadlock for a multi\-threaded process that exits while one or more threads are executing in the memory allocation functions\&. Therefore, this option should only be used with care; it is primarily intended as a performance tuning aid during application development\&. This option is disabled by default\&.
815 "opt\&.junk" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
817 Junk filling enabled/disabled\&. If enabled, each byte of uninitialized allocated memory will be initialized to
818 0xa5\&. All deallocated memory will be initialized to
819 0x5a\&. This is intended for debugging and will impact performance negatively\&. This option is disabled by default unless
820 \fB\-\-enable\-debug\fR
821 is specified during configuration, in which case it is enabled by default unless running inside
822 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2\&.
825 "opt\&.quarantine" (\fBsize_t\fR) r\- [\fB\-\-enable\-fill\fR]
827 Per thread quarantine size in bytes\&. If non\-zero, each thread maintains a FIFO object quarantine that stores up to the specified number of bytes of memory\&. The quarantined memory is not freed until it is released from quarantine, though it is immediately junk\-filled if the
829 option is enabled\&. This feature is of particular use in combination with
830 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2, which can detect attempts to access quarantined objects\&. This is intended for debugging and will impact performance negatively\&. The default quarantine size is 0 unless running inside Valgrind, in which case the default is 16 MiB\&.
833 "opt\&.redzone" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
835 Redzones enabled/disabled\&. If enabled, small allocations have redzones before and after them\&. Furthermore, if the
837 option is enabled, the redzones are checked for corruption during deallocation\&. However, the primary intended purpose of this feature is to be used in combination with
838 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2, which needs redzones in order to do effective buffer overflow/underflow detection\&. This option is intended for debugging and will impact performance negatively\&. This option is disabled by default unless running inside Valgrind\&.
841 "opt\&.zero" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
843 Zero filling enabled/disabled\&. If enabled, each byte of uninitialized allocated memory will be initialized to 0\&. Note that this initialization only happens once for each byte, so
848 calls do not zero memory that was previously allocated\&. This is intended for debugging and will impact performance negatively\&. This option is disabled by default\&.
851 "opt\&.utrace" (\fBbool\fR) r\- [\fB\-\-enable\-utrace\fR]
853 Allocation tracing based on
855 enabled/disabled\&. This option is disabled by default\&.
858 "opt\&.valgrind" (\fBbool\fR) r\- [\fB\-\-enable\-valgrind\fR]
860 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2
861 support enabled/disabled\&. This option is vestigal because jemalloc auto\-detects whether it is running inside Valgrind\&. This option is disabled by default, unless running inside Valgrind\&.
864 "opt\&.xmalloc" (\fBbool\fR) r\- [\fB\-\-enable\-xmalloc\fR]
866 Abort\-on\-out\-of\-memory enabled/disabled\&. If enabled, rather than returning failure for any allocation function, display a diagnostic message on
868 and cause the program to drop core (using
869 \fBabort\fR(3))\&. If an application is designed to depend on this behavior, set the option at compile time by including the following in the source code:
875 malloc_conf = "xmalloc:true";
881 This option is disabled by default\&.
884 "opt\&.tcache" (\fBbool\fR) r\- [\fB\-\-enable\-tcache\fR]
886 Thread\-specific caching enabled/disabled\&. When there are multiple threads, each thread uses a thread\-specific cache for objects up to a certain size\&. Thread\-specific caching allows many allocations to be satisfied without performing any thread synchronization, at the cost of increased memory use\&. See the
887 "opt\&.lg_tcache_max"
888 option for related tuning information\&. This option is enabled by default unless running inside
889 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2\&.
892 "opt\&.lg_tcache_max" (\fBsize_t\fR) r\- [\fB\-\-enable\-tcache\fR]
894 Maximum size class (log base 2) to cache in the thread\-specific cache\&. At a minimum, all small size classes are cached, and at a maximum all large size classes are cached\&. The default maximum is 32 KiB (2^15)\&.
897 "opt\&.prof" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
899 Memory profiling enabled/disabled\&. If enabled, profile memory allocation activity\&. See the
901 option for on\-the\-fly activation/deactivation\&. See the
902 "opt\&.lg_prof_sample"
903 option for probabilistic sampling control\&. See the
905 option for control of cumulative sample reporting\&. See the
906 "opt\&.lg_prof_interval"
907 option for information on interval\-triggered profile dumping, the
909 option for information on high\-water\-triggered profile dumping, and the
911 option for final profile dumping\&. Profile output is compatible with the included
913 Perl script, which originates from the
914 \m[blue]\fBgperftools package\fR\m[]\&\s-2\u[3]\d\s+2\&.
917 "opt\&.prof_prefix" (\fBconst char *\fR) r\- [\fB\-\-enable\-prof\fR]
919 Filename prefix for profile dumps\&. If the prefix is set to the empty string, no automatic dumps will occur; this is primarily useful for disabling the automatic final heap dump (which also disables leak reporting, if enabled)\&. The default prefix is
923 "opt\&.prof_active" (\fBbool\fR) rw [\fB\-\-enable\-prof\fR]
925 Profiling activated/deactivated\&. This is a secondary control mechanism that makes it possible to start the application with profiling enabled (see the
927 option) but inactive, then toggle profiling at any time during program execution with the
929 mallctl\&. This option is enabled by default\&.
932 "opt\&.lg_prof_sample" (\fBssize_t\fR) r\- [\fB\-\-enable\-prof\fR]
934 Average interval (log base 2) between allocation samples, as measured in bytes of allocation activity\&. Increasing the sampling interval decreases profile fidelity, but also decreases the computational overhead\&. The default sample interval is 512 KiB (2^19 B)\&.
937 "opt\&.prof_accum" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
939 Reporting of cumulative object/byte counts in profile dumps enabled/disabled\&. If this option is enabled, every unique backtrace must be stored for the duration of execution\&. Depending on the application, this can impose a large memory overhead, and the cumulative counts are not always of interest\&. This option is disabled by default\&.
942 "opt\&.lg_prof_interval" (\fBssize_t\fR) r\- [\fB\-\-enable\-prof\fR]
944 Average interval (log base 2) between memory profile dumps, as measured in bytes of allocation activity\&. The actual interval between dumps may be sporadic because decentralized allocation counters are used to avoid synchronization bottlenecks\&. Profiles are dumped to files named according to the pattern
945 <prefix>\&.<pid>\&.<seq>\&.i<iseq>\&.heap, where
949 option\&. By default, interval\-triggered profile dumping is disabled (encoded as \-1)\&.
952 "opt\&.prof_gdump" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
954 Trigger a memory profile dump every time the total virtual memory exceeds the previous maximum\&. Profiles are dumped to files named according to the pattern
955 <prefix>\&.<pid>\&.<seq>\&.u<useq>\&.heap, where
959 option\&. This option is disabled by default\&.
962 "opt\&.prof_final" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
966 function to dump final memory usage to a file named according to the pattern
967 <prefix>\&.<pid>\&.<seq>\&.f\&.heap, where
971 option\&. This option is enabled by default\&.
974 "opt\&.prof_leak" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
976 Leak reporting enabled/disabled\&. If enabled, use an
978 function to report memory leaks detected by allocation sampling\&. See the
980 option for information on analyzing heap profile output\&. This option is disabled by default\&.
983 "thread\&.arena" (\fBunsigned\fR) rw
985 Get or set the arena associated with the calling thread\&. If the specified arena was not initialized beforehand (see the
986 "arenas\&.initialized"
987 mallctl), it will be automatically initialized as a side effect of calling this interface\&.
990 "thread\&.allocated" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
992 Get the total number of bytes ever allocated by the calling thread\&. This counter has the potential to wrap around; it is up to the application to appropriately interpret the counter in such cases\&.
995 "thread\&.allocatedp" (\fBuint64_t *\fR) r\- [\fB\-\-enable\-stats\fR]
997 Get a pointer to the the value that is returned by the
999 mallctl\&. This is useful for avoiding the overhead of repeated
1000 \fBmallctl*\fR\fB\fR
1004 "thread\&.deallocated" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1006 Get the total number of bytes ever deallocated by the calling thread\&. This counter has the potential to wrap around; it is up to the application to appropriately interpret the counter in such cases\&.
1009 "thread\&.deallocatedp" (\fBuint64_t *\fR) r\- [\fB\-\-enable\-stats\fR]
1011 Get a pointer to the the value that is returned by the
1012 "thread\&.deallocated"
1013 mallctl\&. This is useful for avoiding the overhead of repeated
1014 \fBmallctl*\fR\fB\fR
1018 "thread\&.tcache\&.enabled" (\fBbool\fR) rw [\fB\-\-enable\-tcache\fR]
1020 Enable/disable calling thread\*(Aqs tcache\&. The tcache is implicitly flushed as a side effect of becoming disabled (see
1021 "thread\&.tcache\&.flush")\&.
1024 "thread\&.tcache\&.flush" (\fBvoid\fR) \-\- [\fB\-\-enable\-tcache\fR]
1026 Flush calling thread\*(Aqs tcache\&. This interface releases all cached objects and internal data structures associated with the calling thread\*(Aqs thread\-specific cache\&. Ordinarily, this interface need not be called, since automatic periodic incremental garbage collection occurs, and the thread cache is automatically discarded when a thread exits\&. However, garbage collection is triggered by allocation activity, so it is possible for a thread that stops allocating/deallocating to retain its cache indefinitely, in which case the developer may find manual flushing useful\&.
1029 "arena\&.<i>\&.purge" (\fBunsigned\fR) \-\-
1031 Purge unused dirty pages for arena <i>, or for all arenas if <i> equals
1032 "arenas\&.narenas"\&.
1035 "arena\&.<i>\&.dss" (\fBconst char *\fR) rw
1037 Set the precedence of dss allocation as related to mmap allocation for arena <i>, or for all arenas if <i> equals
1038 "arenas\&.narenas"\&. See
1040 for supported settings\&.
1043 "arenas\&.narenas" (\fBunsigned\fR) r\-
1045 Current limit on number of arenas\&.
1048 "arenas\&.initialized" (\fBbool *\fR) r\-
1052 booleans\&. Each boolean indicates whether the corresponding arena is initialized\&.
1055 "arenas\&.quantum" (\fBsize_t\fR) r\-
1060 "arenas\&.page" (\fBsize_t\fR) r\-
1065 "arenas\&.tcache_max" (\fBsize_t\fR) r\- [\fB\-\-enable\-tcache\fR]
1067 Maximum thread\-cached size class\&.
1070 "arenas\&.nbins" (\fBunsigned\fR) r\-
1072 Number of bin size classes\&.
1075 "arenas\&.nhbins" (\fBunsigned\fR) r\- [\fB\-\-enable\-tcache\fR]
1077 Total number of thread cache bin size classes\&.
1080 "arenas\&.bin\&.<i>\&.size" (\fBsize_t\fR) r\-
1082 Maximum size supported by size class\&.
1085 "arenas\&.bin\&.<i>\&.nregs" (\fBuint32_t\fR) r\-
1087 Number of regions per page run\&.
1090 "arenas\&.bin\&.<i>\&.run_size" (\fBsize_t\fR) r\-
1092 Number of bytes per page run\&.
1095 "arenas\&.nlruns" (\fBsize_t\fR) r\-
1097 Total number of large size classes\&.
1100 "arenas\&.lrun\&.<i>\&.size" (\fBsize_t\fR) r\-
1102 Maximum size supported by this large size class\&.
1105 "arenas\&.purge" (\fBunsigned\fR) \-w
1107 Purge unused dirty pages for the specified arena, or for all arenas if none is specified\&.
1110 "arenas\&.extend" (\fBunsigned\fR) r\-
1112 Extend the array of arenas by appending a new arena, and returning the new arena index\&.
1115 "prof\&.active" (\fBbool\fR) rw [\fB\-\-enable\-prof\fR]
1117 Control whether sampling is currently active\&. See the
1119 option for additional information\&.
1122 "prof\&.dump" (\fBconst char *\fR) \-w [\fB\-\-enable\-prof\fR]
1124 Dump a memory profile to the specified file, or if NULL is specified, to a file according to the pattern
1125 <prefix>\&.<pid>\&.<seq>\&.m<mseq>\&.heap, where
1127 is controlled by the
1132 "prof\&.interval" (\fBuint64_t\fR) r\- [\fB\-\-enable\-prof\fR]
1134 Average number of bytes allocated between inverval\-based profile dumps\&. See the
1135 "opt\&.lg_prof_interval"
1136 option for additional information\&.
1139 "stats\&.cactive" (\fBsize_t *\fR) r\- [\fB\-\-enable\-stats\fR]
1141 Pointer to a counter that contains an approximate count of the current number of bytes in active pages\&. The estimate may be high, but never low, because each arena rounds up to the nearest multiple of the chunk size when computing its contribution to the counter\&. Note that the
1143 mallctl has no bearing on this counter\&. Furthermore, counter consistency is maintained via atomic operations, so it is necessary to use an atomic operation in order to guarantee a consistent read when dereferencing the pointer\&.
1146 "stats\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1148 Total number of bytes allocated by the application\&.
1151 "stats\&.active" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1153 Total number of bytes in active pages allocated by the application\&. This is a multiple of the page size, and greater than or equal to
1154 "stats\&.allocated"\&. This does not include
1155 "stats\&.arenas\&.<i>\&.pdirty"
1156 and pages entirely devoted to allocator metadata\&.
1159 "stats\&.mapped" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1161 Total number of bytes in chunks mapped on behalf of the application\&. This is a multiple of the chunk size, and is at least as large as
1162 "stats\&.active"\&. This does not include inactive chunks\&.
1165 "stats\&.chunks\&.current" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1167 Total number of chunks actively mapped on behalf of the application\&. This does not include inactive chunks\&.
1170 "stats\&.chunks\&.total" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1172 Cumulative number of chunks allocated\&.
1175 "stats\&.chunks\&.high" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1177 Maximum number of active chunks at any time thus far\&.
1180 "stats\&.huge\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1182 Number of bytes currently allocated by huge objects\&.
1185 "stats\&.huge\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1187 Cumulative number of huge allocation requests\&.
1190 "stats\&.huge\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1192 Cumulative number of huge deallocation requests\&.
1195 "stats\&.arenas\&.<i>\&.dss" (\fBconst char *\fR) r\-
1197 dss (\fBsbrk\fR(2)) allocation precedence as related to
1204 "stats\&.arenas\&.<i>\&.nthreads" (\fBunsigned\fR) r\-
1206 Number of threads currently assigned to arena\&.
1209 "stats\&.arenas\&.<i>\&.pactive" (\fBsize_t\fR) r\-
1211 Number of pages in active runs\&.
1214 "stats\&.arenas\&.<i>\&.pdirty" (\fBsize_t\fR) r\-
1216 Number of pages within unused runs that are potentially dirty, and for which
1217 \fBmadvise\fR\fB\fI\&.\&.\&.\fR\fR\fB \fR\fB\fI\fBMADV_DONTNEED\fR\fR\fR
1218 or similar has not been called\&.
1221 "stats\&.arenas\&.<i>\&.mapped" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1223 Number of mapped bytes\&.
1226 "stats\&.arenas\&.<i>\&.npurge" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1228 Number of dirty page purge sweeps performed\&.
1231 "stats\&.arenas\&.<i>\&.nmadvise" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1234 \fBmadvise\fR\fB\fI\&.\&.\&.\fR\fR\fB \fR\fB\fI\fBMADV_DONTNEED\fR\fR\fR
1235 or similar calls made to purge dirty pages\&.
1238 "stats\&.arenas\&.<i>\&.purged" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1240 Number of pages purged\&.
1243 "stats\&.arenas\&.<i>\&.small\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1245 Number of bytes currently allocated by small objects\&.
1248 "stats\&.arenas\&.<i>\&.small\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1250 Cumulative number of allocation requests served by small bins\&.
1253 "stats\&.arenas\&.<i>\&.small\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1255 Cumulative number of small objects returned to bins\&.
1258 "stats\&.arenas\&.<i>\&.small\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1260 Cumulative number of small allocation requests\&.
1263 "stats\&.arenas\&.<i>\&.large\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1265 Number of bytes currently allocated by large objects\&.
1268 "stats\&.arenas\&.<i>\&.large\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1270 Cumulative number of large allocation requests served directly by the arena\&.
1273 "stats\&.arenas\&.<i>\&.large\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1275 Cumulative number of large deallocation requests served directly by the arena\&.
1278 "stats\&.arenas\&.<i>\&.large\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1280 Cumulative number of large allocation requests\&.
1283 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1285 Current number of bytes allocated by bin\&.
1288 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1290 Cumulative number of allocations served by bin\&.
1293 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1295 Cumulative number of allocations returned to bin\&.
1298 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1300 Cumulative number of allocation requests\&.
1303 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nfills" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR \fB\-\-enable\-tcache\fR]
1305 Cumulative number of tcache fills\&.
1308 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nflushes" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR \fB\-\-enable\-tcache\fR]
1310 Cumulative number of tcache flushes\&.
1313 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nruns" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1315 Cumulative number of runs created\&.
1318 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.nreruns" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1320 Cumulative number of times the current run from which to allocate changed\&.
1323 "stats\&.arenas\&.<i>\&.bins\&.<j>\&.curruns" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1325 Current number of runs\&.
1328 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1330 Cumulative number of allocation requests for this size class served directly by the arena\&.
1333 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1335 Cumulative number of deallocation requests for this size class served directly by the arena\&.
1338 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1340 Cumulative number of allocation requests for this size class\&.
1343 "stats\&.arenas\&.<i>\&.lruns\&.<j>\&.curruns" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1345 Current number of runs for this size class\&.
1347 .SH "DEBUGGING MALLOC PROBLEMS"
1349 When debugging, it is a good idea to configure/build jemalloc with the
1350 \fB\-\-enable\-debug\fR
1352 \fB\-\-enable\-fill\fR
1353 options, and recompile the program with suitable options and symbols for debugger support\&. When so configured, jemalloc incorporates a wide variety of run\-time assertions that catch application errors such as double\-free, write\-after\-free, etc\&.
1355 Programs often accidentally depend on \(lquninitialized\(rq memory actually being filled with zero bytes\&. Junk filling (see the
1357 option) tends to expose such bugs in the form of obviously incorrect results and/or coredumps\&. Conversely, zero filling (see the
1359 option) eliminates the symptoms of such bugs\&. Between these two options, it is usually possible to quickly detect, diagnose, and eliminate such bugs\&.
1361 This implementation does not provide much detail about the problems it detects, because the performance impact for storing such information would be prohibitive\&. However, jemalloc does integrate with the most excellent
1362 \m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2
1364 \fB\-\-enable\-valgrind\fR
1365 configuration option is enabled\&.
1366 .SH "DIAGNOSTIC MESSAGES"
1368 If any of the memory allocation/deallocation functions detect an error or warning condition, a message will be printed to file descriptor
1369 \fBSTDERR_FILENO\fR\&. Errors will result in the process dumping core\&. If the
1371 option is set, most warnings are treated as errors\&.
1374 \fImalloc_message\fR
1375 variable allows the programmer to override the function which emits the text strings forming the errors and warnings if for some reason the
1377 file descriptor is not suitable for this\&.
1378 \fBmalloc_message\fR\fB\fR
1381 pointer argument that is
1383 unless overridden by the arguments in a call to
1384 \fBmalloc_stats_print\fR\fB\fR, followed by a string pointer\&. Please note that doing anything which tries to allocate memory in this function is likely to result in a crash or deadlock\&.
1386 All messages are prefixed by \(lq<jemalloc>:\(rq\&.
1394 functions return a pointer to the allocated memory if successful; otherwise a
1396 pointer is returned and
1402 \fBposix_memalign\fR\fB\fR
1403 function returns the value 0 if successful; otherwise it returns an error value\&. The
1404 \fBposix_memalign\fR\fB\fR
1405 function will fail if:
1411 parameter is not a power of 2 at least as large as
1412 sizeof(\fBvoid *\fR)\&.
1417 Memory allocation error\&.
1421 \fBaligned_alloc\fR\fB\fR
1422 function returns a pointer to the allocated memory if successful; otherwise a
1424 pointer is returned and
1427 \fBaligned_alloc\fR\fB\fR
1428 function will fail if:
1434 parameter is not a power of 2\&.
1439 Memory allocation error\&.
1444 function returns a pointer, possibly identical to
1445 \fIptr\fR, to the allocated memory if successful; otherwise a
1447 pointer is returned, and
1451 if the error was the result of an allocation failure\&. The
1453 function always leaves the original buffer intact when an error occurs\&.
1457 function returns no value\&.
1458 .SS "Non\-standard API"
1464 functions return a pointer to the allocated memory if successful; otherwise a
1466 pointer is returned to indicate insufficient contiguous memory was available to service the allocation request\&.
1470 function returns the real size of the resulting resized allocation pointed to by
1471 \fIptr\fR, which is a value less than
1473 if the allocation could not be adequately grown in place\&.
1477 function returns the real size of the allocation pointed to by
1482 returns the real size that would result from a successful equivalent
1484 function call, or zero if insufficient memory is available to perform the size computation\&.
1487 \fBmallctl\fR\fB\fR,
1488 \fBmallctlnametomib\fR\fB\fR, and
1489 \fBmallctlbymib\fR\fB\fR
1490 functions return 0 on success; otherwise they return an error value\&. The functions will fail if:
1498 is too large or too small\&. Alternatively,
1500 is too large or too small; in this case as much data as possible are read despite the error\&.
1508 specifies an unknown/invalid value\&.
1513 Attempt to read or write void value, or attempt to write read\-only value\&.
1518 A memory allocation failure occurred\&.
1523 An interface with side effects failed in some way not directly related to
1524 \fBmallctl*\fR\fB\fR
1525 read/write processing\&.
1529 \fBmalloc_usable_size\fR\fB\fR
1530 function returns the usable size of the allocation pointed to by
1532 .SS "Experimental API"
1536 \fBrallocm\fR\fB\fR,
1537 \fBsallocm\fR\fB\fR,
1538 \fBdallocm\fR\fB\fR, and
1541 \fBALLOCM_SUCCESS\fR
1542 on success; otherwise they return an error value\&. The
1544 \fBrallocm\fR\fB\fR, and
1546 functions will fail if:
1550 Out of memory\&. Insufficient contiguous memory was available to service the allocation request\&. The
1552 function additionally sets
1555 \fBNULL\fR, whereas the
1563 function will also fail if:
1565 ALLOCM_ERR_NOT_MOVED
1567 \fBALLOCM_NO_MOVE\fR
1568 was specified, but the reallocation request could not be serviced without moving the object\&.
1572 The following environment variable affects the execution of the allocation functions:
1576 If the environment variable
1578 is set, the characters it contains will be interpreted as options\&.
1582 To dump core whenever a problem occurs:
1588 ln \-s \*(Aqabort:true\*(Aq /etc/malloc\&.conf
1594 To specify in the source a chunk size that is 16 MiB:
1600 malloc_conf = "lg_chunk:24";
1613 \fBgetpagesize\fR(3)
1619 \fBrealloc\fR\fB\fR, and
1621 functions conform to ISO/IEC 9899:1990 (\(lqISO C90\(rq)\&.
1624 \fBposix_memalign\fR\fB\fR
1625 function conforms to IEEE Std 1003\&.1\-2001 (\(lqPOSIX\&.1\(rq)\&.
1629 \fBmalloc_usable_size\fR\fB\fR
1631 \fBposix_memalign\fR\fB\fR
1632 functions first appeared in FreeBSD 7\&.0\&.
1635 \fBaligned_alloc\fR\fB\fR,
1636 \fBmalloc_stats_print\fR\fB\fR,
1637 \fBmallctl*\fR\fB\fR, and
1639 functions first appeared in FreeBSD 10\&.0\&.
1643 functions first appeared in FreeBSD 11\&.0\&.
1653 \%http://www.canonware.com/jemalloc/
1658 \%http://valgrind.org/
1663 \%http://code.google.com/p/gperftools/