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.\" Author: Jason Evans
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.\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
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.\" Manual: User Manual
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.\" Source: jemalloc 3.3.1-0-g9ef9d9e8c271cdf14f664b871a8f98c827714784
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.TH "JEMALLOC" "3" "03/06/2013" "jemalloc 3.3.1-0-g9ef9d9e8c271" "User Manual"
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.\" * MAIN CONTENT STARTS HERE *
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.\" -----------------------------------------------------------------
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jemalloc \- general purpose memory allocation functions
34
This manual describes jemalloc 3\&.3\&.1\-0\-g9ef9d9e8c271cdf14f664b871a8f98c827714784\&. More information can be found at the
35
\m[blue]\fBjemalloc website\fR\m[]\&\s-2\u[1]\d\s+2\&.
41
#include <jemalloc/jemalloc\&.h>
45
.HP \w'void\ *malloc('u
46
.BI "void *malloc(size_t\ " "size" ");"
47
.HP \w'void\ *calloc('u
48
.BI "void *calloc(size_t\ " "number" ", size_t\ " "size" ");"
49
.HP \w'int\ posix_memalign('u
50
.BI "int posix_memalign(void\ **" "ptr" ", size_t\ " "alignment" ", size_t\ " "size" ");"
51
.HP \w'void\ *aligned_alloc('u
52
.BI "void *aligned_alloc(size_t\ " "alignment" ", size_t\ " "size" ");"
53
.HP \w'void\ *realloc('u
54
.BI "void *realloc(void\ *" "ptr" ", size_t\ " "size" ");"
56
.BI "void free(void\ *" "ptr" ");"
57
.SS "Non\-standard API"
58
.HP \w'size_t\ malloc_usable_size('u
59
.BI "size_t malloc_usable_size(const\ void\ *" "ptr" ");"
60
.HP \w'void\ malloc_stats_print('u
61
.BI "void malloc_stats_print(void\ " "(*write_cb)" "\ (void\ *,\ const\ char\ *), void\ *" "cbopaque" ", const\ char\ *" "opts" ");"
62
.HP \w'int\ mallctl('u
63
.BI "int mallctl(const\ char\ *" "name" ", void\ *" "oldp" ", size_t\ *" "oldlenp" ", void\ *" "newp" ", size_t\ " "newlen" ");"
64
.HP \w'int\ mallctlnametomib('u
65
.BI "int mallctlnametomib(const\ char\ *" "name" ", size_t\ *" "mibp" ", size_t\ *" "miblenp" ");"
66
.HP \w'int\ mallctlbymib('u
67
.BI "int mallctlbymib(const\ size_t\ *" "mib" ", size_t\ " "miblen" ", void\ *" "oldp" ", size_t\ *" "oldlenp" ", void\ *" "newp" ", size_t\ " "newlen" ");"
68
.HP \w'void\ (*malloc_message)('u
69
.BI "void (*malloc_message)(void\ *" "cbopaque" ", const\ char\ *" "s" ");"
71
const char *\fImalloc_conf\fR;
72
.SS "Experimental API"
74
.BI "int allocm(void\ **" "ptr" ", size_t\ *" "rsize" ", size_t\ " "size" ", int\ " "flags" ");"
75
.HP \w'int\ rallocm('u
76
.BI "int rallocm(void\ **" "ptr" ", size_t\ *" "rsize" ", size_t\ " "size" ", size_t\ " "extra" ", int\ " "flags" ");"
77
.HP \w'int\ sallocm('u
78
.BI "int sallocm(const\ void\ *" "ptr" ", size_t\ *" "rsize" ", int\ " "flags" ");"
79
.HP \w'int\ dallocm('u
80
.BI "int dallocm(void\ *" "ptr" ", int\ " "flags" ");"
81
.HP \w'int\ nallocm('u
82
.BI "int nallocm(size_t\ *" "rsize" ", size_t\ " "size" ", int\ " "flags" ");"
90
bytes of uninitialized memory\&. The allocated space is suitably aligned (after possible pointer coercion) for storage of any type of object\&.
94
function allocates space for
98
bytes in length\&. The result is identical to calling
103
\fIsize\fR, with the exception that the allocated memory is explicitly initialized to zero bytes\&.
106
\fBposix_memalign\fR\fB\fR
109
bytes of memory such that the allocation\*(Aqs base address is an even multiple of
110
\fIalignment\fR, and returns the allocation in the value pointed to by
111
\fIptr\fR\&. The requested
113
must be a power of 2 at least as large as
114
sizeof(\fBvoid *\fR)\&.
117
\fBaligned_alloc\fR\fB\fR
120
bytes of memory such that the allocation\*(Aqs base address is an even multiple of
121
\fIalignment\fR\&. The requested
123
must be a power of 2\&. Behavior is undefined if
125
is not an integral multiple of
130
function changes the size of the previously allocated memory referenced by
134
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
136
is freed and a pointer to the newly allocated memory is returned\&. Note that
138
may move the memory allocation, resulting in a different return value than
144
function behaves identically to
146
for the specified size\&.
150
function causes the allocated memory referenced by
152
to be made available for future allocations\&. If
155
\fBNULL\fR, no action occurs\&.
156
.SS "Non\-standard API"
159
\fBmalloc_usable_size\fR\fB\fR
160
function returns the usable size of the allocation pointed to by
161
\fIptr\fR\&. The return value may be larger than the size that was requested during allocation\&. The
162
\fBmalloc_usable_size\fR\fB\fR
163
function is not a mechanism for in\-place
164
\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
165
\fBmalloc_usable_size\fR\fB\fR
166
should not be depended on, since such behavior is entirely implementation\-dependent\&.
169
\fBmalloc_stats_print\fR\fB\fR
170
function writes human\-readable summary statistics via the
172
callback function pointer and
176
\fBmalloc_message\fR\fB\fR
180
\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
183
\fBmalloc_message\fR\fB\fR
186
functions internally, so inconsistent statistics can be reported if multiple threads use these functions simultaneously\&. If
187
\fB\-\-enable\-stats\fR
188
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\&.
192
function provides a general interface for introspecting the memory allocator, as well as setting modifiable parameters and triggering actions\&. The period\-separated
194
argument specifies a location in a tree\-structured namespace; see the
196
section for documentation on the tree contents\&. To read a value, pass a pointer via
198
to adequate space to contain the value, and a pointer to its length via
199
\fIoldlenp\fR; otherwise pass
202
\fBNULL\fR\&. Similarly, to write a value, pass a pointer to the value via
203
\fInewp\fR, and its length via
204
\fInewlen\fR; otherwise pass
210
\fBmallctlnametomib\fR\fB\fR
211
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
212
\fBmallctlbymib\fR\fB\fR\&. Upon successful return from
213
\fBmallctlnametomib\fR\fB\fR,
219
is the lesser of the number of components in
221
and the input value of
222
\fI*miblenp\fR\&. Thus it is possible to pass a
224
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
225
"arenas\&.bin\&.2\&.size"), the corresponding MIB component will always be that integer\&. Therefore, it is legitimate to construct code like the following:
237
mallctl("arenas\&.nbins", &nbins, &len, NULL, 0);
240
mallnametomib("arenas\&.bin\&.0\&.size", mib, &miblen);
241
for (i = 0; i < nbins; i++) {
245
len = sizeof(bin_size);
246
mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0);
247
/* Do something with bin_size\&.\&.\&. */
253
.SS "Experimental API"
255
The experimental API is subject to change or removal without regard for backward compatibility\&. If
256
\fB\-\-disable\-experimental\fR
257
is specified during configuration, the experimental API is omitted\&.
263
\fBdallocm\fR\fB\fR, and
267
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:
269
\fBALLOCM_LG_ALIGN(\fR\fB\fIla\fR\fR\fB) \fR
271
Align the memory allocation to start at an address that is a multiple of
272
(1 << \fIla\fR)\&. This macro does not validate that
274
is within the valid range\&.
277
\fBALLOCM_ALIGN(\fR\fB\fIa\fR\fR\fB) \fR
279
Align the memory allocation to start at an address that is a multiple of
282
is a power of two\&. This macro does not validate that
289
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 option is absent, newly allocated memory is uninitialized\&.
294
For reallocation, fail rather than moving the object\&. This constraint can apply to both growth and shrinkage\&.
297
\fBALLOCM_ARENA(\fR\fB\fIa\fR\fR\fB) \fR
299
Use the arena specified by the index
300
\fIa\fR\&. This macro does not validate that
302
specifies an arena in the valid range\&.
307
function allocates at least
309
bytes of memory, sets
311
to the base address of the allocation, and sets
313
to the real size of the allocation if
316
\fBNULL\fR\&. Behavior is undefined if
323
function resizes the allocation at
329
to the base address of the allocation if it moved, and sets
331
to the real size of the allocation if
336
is non\-zero, an attempt is made to resize the allocation to be at least
337
\fIsize\fR + \fIextra\fR)
338
bytes, though inability to allocate the extra byte(s) will not by itself result in failure\&. Behavior is undefined if
342
(\fIsize\fR + \fIextra\fR > \fBSIZE_T_MAX\fR)\&.
348
to the real size of the allocation\&.
352
function causes the memory referenced by
354
to be made available for future allocations\&.
358
function allocates no memory, but it performs the same size computation as the
366
to the real size of the allocation that would result from the equivalent
368
function call\&. Behavior is undefined if
374
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\&.
376
The string pointed to by the global variable
377
\fImalloc_conf\fR, the \(lqname\(rq of the file referenced by the symbolic link named
378
/etc/malloc\&.conf, and the value of the environment variable
379
\fBMALLOC_CONF\fR, will be interpreted, in that order, from left to right as options\&.
381
An options string is a comma\-separated list of option:value pairs\&. There is one key corresponding to each
385
section for options documentation)\&. For example,
391
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\&.
392
.SH "IMPLEMENTATION NOTES"
394
Traditionally, allocators have used
396
to obtain memory, which is suboptimal for several reasons, including race conditions, increased fragmentation, and artificial limitations on maximum usable memory\&. If
397
\fB\-\-enable\-dss\fR
398
is specified during configuration, this allocator uses both
401
\fBsbrk\fR(2), in that order of preference; otherwise only
405
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\&.
407
In addition to multiple arenas, unless
408
\fB\-\-disable\-tcache\fR
409
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\&.
411
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\&.
413
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\&.
415
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\&.
417
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
418
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
420
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\&.
422
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\&.
424
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
428
.nr an-no-space-flag 1
431
.B Table\ \&1.\ \&Size classes
462
[16, 32, 48, \&.\&.\&., 128]
477
[640, 768, 896, 1024]
482
[1280, 1536, 1792, 2048]
494
[4 KiB, 8 KiB, 12 KiB, \&.\&.\&., 4072 KiB]
501
[4 MiB, 8 MiB, 12 MiB, \&.\&.\&.]
505
.SH "MALLCTL NAMESPACE"
507
The following names are defined in the namespace accessible via the
509
functions\&. Value types are specified in parentheses, their readable/writable statuses are encoded as
513
\-\-, and required build configuration flags follow, if any\&. A name element encoded as
517
indicates an integer component, where the integer varies from 0 to some upper value that must be determined via introspection\&. In the case of
518
"stats\&.arenas\&.<i>\&.*",
522
can be used to access the summation of statistics from all arenas\&. Take special note of the
524
mallctl, which controls refreshing of cached dynamic statistics\&.
526
"version" (\fBconst char *\fR) r\-
528
Return the jemalloc version string\&.
531
"epoch" (\fBuint64_t\fR) rw
533
If a value is passed in, refresh the data from which the
535
functions report values, and increment the epoch\&. Return the current epoch\&. This is useful for detecting whether another thread caused a refresh\&.
538
"config\&.debug" (\fBbool\fR) r\-
540
\fB\-\-enable\-debug\fR
541
was specified during build configuration\&.
544
"config\&.dss" (\fBbool\fR) r\-
546
\fB\-\-enable\-dss\fR
547
was specified during build configuration\&.
550
"config\&.fill" (\fBbool\fR) r\-
552
\fB\-\-enable\-fill\fR
553
was specified during build configuration\&.
556
"config\&.lazy_lock" (\fBbool\fR) r\-
558
\fB\-\-enable\-lazy\-lock\fR
559
was specified during build configuration\&.
562
"config\&.mremap" (\fBbool\fR) r\-
564
\fB\-\-enable\-mremap\fR
565
was specified during build configuration\&.
568
"config\&.munmap" (\fBbool\fR) r\-
570
\fB\-\-enable\-munmap\fR
571
was specified during build configuration\&.
574
"config\&.prof" (\fBbool\fR) r\-
576
\fB\-\-enable\-prof\fR
577
was specified during build configuration\&.
580
"config\&.prof_libgcc" (\fBbool\fR) r\-
582
\fB\-\-disable\-prof\-libgcc\fR
583
was not specified during build configuration\&.
586
"config\&.prof_libunwind" (\fBbool\fR) r\-
588
\fB\-\-enable\-prof\-libunwind\fR
589
was specified during build configuration\&.
592
"config\&.stats" (\fBbool\fR) r\-
594
\fB\-\-enable\-stats\fR
595
was specified during build configuration\&.
598
"config\&.tcache" (\fBbool\fR) r\-
600
\fB\-\-disable\-tcache\fR
601
was not specified during build configuration\&.
604
"config\&.tls" (\fBbool\fR) r\-
606
\fB\-\-disable\-tls\fR
607
was not specified during build configuration\&.
610
"config\&.utrace" (\fBbool\fR) r\-
612
\fB\-\-enable\-utrace\fR
613
was specified during build configuration\&.
616
"config\&.valgrind" (\fBbool\fR) r\-
618
\fB\-\-enable\-valgrind\fR
619
was specified during build configuration\&.
622
"config\&.xmalloc" (\fBbool\fR) r\-
624
\fB\-\-enable\-xmalloc\fR
625
was specified during build configuration\&.
628
"opt\&.abort" (\fBbool\fR) r\-
630
Abort\-on\-warning enabled/disabled\&. If true, most warnings are fatal\&. The process will call
632
in these cases\&. This option is disabled by default unless
633
\fB\-\-enable\-debug\fR
634
is specified during configuration, in which case it is enabled by default\&.
637
"opt\&.lg_chunk" (\fBsize_t\fR) r\-
639
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)\&.
642
"opt\&.dss" (\fBconst char *\fR) r\-
644
dss (\fBsbrk\fR(2)) allocation precedence as related to
646
allocation\&. The following settings are supported: \(lqdisabled\(rq, \(lqprimary\(rq, and \(lqsecondary\(rq (default)\&.
649
"opt\&.narenas" (\fBsize_t\fR) r\-
651
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\&.
654
"opt\&.lg_dirty_mult" (\fBssize_t\fR) r\-
656
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
658
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\&.
661
"opt\&.stats_print" (\fBbool\fR) r\-
663
Enable/disable statistics printing at exit\&. If enabled, the
664
\fBmalloc_stats_print\fR\fB\fR
665
function is called at program exit via an
668
\fB\-\-enable\-stats\fR
669
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\&.
672
"opt\&.junk" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
674
Junk filling enabled/disabled\&. If enabled, each byte of uninitialized allocated memory will be initialized to
675
0xa5\&. All deallocated memory will be initialized to
676
0x5a\&. This is intended for debugging and will impact performance negatively\&. This option is disabled by default unless
677
\fB\-\-enable\-debug\fR
678
is specified during configuration, in which case it is enabled by default unless running inside
679
\m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2\&.
682
"opt\&.quarantine" (\fBsize_t\fR) r\- [\fB\-\-enable\-fill\fR]
684
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
686
option is enabled\&. This feature is of particular use in combination with
687
\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\&.
690
"opt\&.redzone" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
692
Redzones enabled/disabled\&. If enabled, small allocations have redzones before and after them\&. Furthermore, if the
694
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
695
\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\&.
698
"opt\&.zero" (\fBbool\fR) r\- [\fB\-\-enable\-fill\fR]
700
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
704
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\&.
707
"opt\&.utrace" (\fBbool\fR) r\- [\fB\-\-enable\-utrace\fR]
709
Allocation tracing based on
711
enabled/disabled\&. This option is disabled by default\&.
714
"opt\&.valgrind" (\fBbool\fR) r\- [\fB\-\-enable\-valgrind\fR]
716
\m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2
717
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\&.
720
"opt\&.xmalloc" (\fBbool\fR) r\- [\fB\-\-enable\-xmalloc\fR]
722
Abort\-on\-out\-of\-memory enabled/disabled\&. If enabled, rather than returning failure for any allocation function, display a diagnostic message on
724
and cause the program to drop core (using
725
\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:
731
malloc_conf = "xmalloc:true";
737
This option is disabled by default\&.
740
"opt\&.tcache" (\fBbool\fR) r\- [\fB\-\-enable\-tcache\fR]
742
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
743
"opt\&.lg_tcache_max"
744
option for related tuning information\&. This option is enabled by default unless running inside
745
\m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2\&.
748
"opt\&.lg_tcache_max" (\fBsize_t\fR) r\- [\fB\-\-enable\-tcache\fR]
750
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)\&.
753
"opt\&.prof" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
755
Memory profiling enabled/disabled\&. If enabled, profile memory allocation activity\&. See the
757
option for on\-the\-fly activation/deactivation\&. See the
758
"opt\&.lg_prof_sample"
759
option for probabilistic sampling control\&. See the
761
option for control of cumulative sample reporting\&. See the
762
"opt\&.lg_prof_interval"
763
option for information on interval\-triggered profile dumping, the
765
option for information on high\-water\-triggered profile dumping, and the
767
option for final profile dumping\&. Profile output is compatible with the included
769
Perl script, which originates from the
770
\m[blue]\fBgperftools package\fR\m[]\&\s-2\u[3]\d\s+2\&.
773
"opt\&.prof_prefix" (\fBconst char *\fR) r\- [\fB\-\-enable\-prof\fR]
775
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
779
"opt\&.prof_active" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
781
Profiling activated/deactivated\&. This is a secondary control mechanism that makes it possible to start the application with profiling enabled (see the
783
option) but inactive, then toggle profiling at any time during program execution with the
785
mallctl\&. This option is enabled by default\&.
788
"opt\&.lg_prof_sample" (\fBssize_t\fR) r\- [\fB\-\-enable\-prof\fR]
790
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)\&.
793
"opt\&.prof_accum" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
795
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\&.
798
"opt\&.lg_prof_interval" (\fBssize_t\fR) r\- [\fB\-\-enable\-prof\fR]
800
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
801
<prefix>\&.<pid>\&.<seq>\&.i<iseq>\&.heap, where
805
option\&. By default, interval\-triggered profile dumping is disabled (encoded as \-1)\&.
808
"opt\&.prof_gdump" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
810
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
811
<prefix>\&.<pid>\&.<seq>\&.u<useq>\&.heap, where
815
option\&. This option is disabled by default\&.
818
"opt\&.prof_final" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
822
function to dump final memory usage to a file named according to the pattern
823
<prefix>\&.<pid>\&.<seq>\&.f\&.heap, where
827
option\&. This option is enabled by default\&.
830
"opt\&.prof_leak" (\fBbool\fR) r\- [\fB\-\-enable\-prof\fR]
832
Leak reporting enabled/disabled\&. If enabled, use an
834
function to report memory leaks detected by allocation sampling\&. See the
836
option for information on analyzing heap profile output\&. This option is disabled by default\&.
839
"thread\&.arena" (\fBunsigned\fR) rw
841
Get or set the arena associated with the calling thread\&. If the specified arena was not initialized beforehand (see the
842
"arenas\&.initialized"
843
mallctl), it will be automatically initialized as a side effect of calling this interface\&.
846
"thread\&.allocated" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
848
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\&.
851
"thread\&.allocatedp" (\fBuint64_t *\fR) r\- [\fB\-\-enable\-stats\fR]
853
Get a pointer to the the value that is returned by the
855
mallctl\&. This is useful for avoiding the overhead of repeated
860
"thread\&.deallocated" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
862
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\&.
865
"thread\&.deallocatedp" (\fBuint64_t *\fR) r\- [\fB\-\-enable\-stats\fR]
867
Get a pointer to the the value that is returned by the
868
"thread\&.deallocated"
869
mallctl\&. This is useful for avoiding the overhead of repeated
874
"thread\&.tcache\&.enabled" (\fBbool\fR) rw [\fB\-\-enable\-tcache\fR]
876
Enable/disable calling thread\*(Aqs tcache\&. The tcache is implicitly flushed as a side effect of becoming disabled (see
877
"thread\&.tcache\&.flush")\&.
880
"thread\&.tcache\&.flush" (\fBvoid\fR) \-\- [\fB\-\-enable\-tcache\fR]
882
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\&.
885
"arena\&.<i>\&.purge" (\fBunsigned\fR) \-\-
887
Purge unused dirty pages for arena <i>, or for all arenas if <i> equals
888
"arenas\&.narenas"\&.
891
"arena\&.<i>\&.dss" (\fBconst char *\fR) rw
893
Set the precedence of dss allocation as related to mmap allocation for arena <i>, or for all arenas if <i> equals
894
"arenas\&.narenas"\&. See
896
for supported settings\&.
899
"arenas\&.narenas" (\fBunsigned\fR) r\-
901
Current limit on number of arenas\&.
904
"arenas\&.initialized" (\fBbool *\fR) r\-
908
booleans\&. Each boolean indicates whether the corresponding arena is initialized\&.
911
"arenas\&.quantum" (\fBsize_t\fR) r\-
916
"arenas\&.page" (\fBsize_t\fR) r\-
921
"arenas\&.tcache_max" (\fBsize_t\fR) r\- [\fB\-\-enable\-tcache\fR]
923
Maximum thread\-cached size class\&.
926
"arenas\&.nbins" (\fBunsigned\fR) r\-
928
Number of bin size classes\&.
931
"arenas\&.nhbins" (\fBunsigned\fR) r\- [\fB\-\-enable\-tcache\fR]
933
Total number of thread cache bin size classes\&.
936
"arenas\&.bin\&.<i>\&.size" (\fBsize_t\fR) r\-
938
Maximum size supported by size class\&.
941
"arenas\&.bin\&.<i>\&.nregs" (\fBuint32_t\fR) r\-
943
Number of regions per page run\&.
946
"arenas\&.bin\&.<i>\&.run_size" (\fBsize_t\fR) r\-
948
Number of bytes per page run\&.
951
"arenas\&.nlruns" (\fBsize_t\fR) r\-
953
Total number of large size classes\&.
956
"arenas\&.lrun\&.<i>\&.size" (\fBsize_t\fR) r\-
958
Maximum size supported by this large size class\&.
961
"arenas\&.purge" (\fBunsigned\fR) \-w
963
Purge unused dirty pages for the specified arena, or for all arenas if none is specified\&.
966
"arenas\&.extend" (\fBunsigned\fR) r\-
968
Extend the array of arenas by appending a new arena, and returning the new arena index\&.
971
"prof\&.active" (\fBbool\fR) rw [\fB\-\-enable\-prof\fR]
973
Control whether sampling is currently active\&. See the
975
option for additional information\&.
978
"prof\&.dump" (\fBconst char *\fR) \-w [\fB\-\-enable\-prof\fR]
980
Dump a memory profile to the specified file, or if NULL is specified, to a file according to the pattern
981
<prefix>\&.<pid>\&.<seq>\&.m<mseq>\&.heap, where
988
"prof\&.interval" (\fBuint64_t\fR) r\- [\fB\-\-enable\-prof\fR]
990
Average number of bytes allocated between inverval\-based profile dumps\&. See the
991
"opt\&.lg_prof_interval"
992
option for additional information\&.
995
"stats\&.cactive" (\fBsize_t *\fR) r\- [\fB\-\-enable\-stats\fR]
997
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
999
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\&.
1002
"stats\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1004
Total number of bytes allocated by the application\&.
1007
"stats\&.active" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1009
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
1010
"stats\&.allocated"\&. This does not include
1011
"stats\&.arenas\&.<i>\&.pdirty"
1012
and pages entirely devoted to allocator metadata\&.
1015
"stats\&.mapped" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1017
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
1018
"stats\&.active"\&. This does not include inactive chunks\&.
1021
"stats\&.chunks\&.current" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1023
Total number of chunks actively mapped on behalf of the application\&. This does not include inactive chunks\&.
1026
"stats\&.chunks\&.total" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1028
Cumulative number of chunks allocated\&.
1031
"stats\&.chunks\&.high" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1033
Maximum number of active chunks at any time thus far\&.
1036
"stats\&.huge\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1038
Number of bytes currently allocated by huge objects\&.
1041
"stats\&.huge\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1043
Cumulative number of huge allocation requests\&.
1046
"stats\&.huge\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1048
Cumulative number of huge deallocation requests\&.
1051
"stats\&.arenas\&.<i>\&.dss" (\fBconst char *\fR) r\-
1053
dss (\fBsbrk\fR(2)) allocation precedence as related to
1060
"stats\&.arenas\&.<i>\&.nthreads" (\fBunsigned\fR) r\-
1062
Number of threads currently assigned to arena\&.
1065
"stats\&.arenas\&.<i>\&.pactive" (\fBsize_t\fR) r\-
1067
Number of pages in active runs\&.
1070
"stats\&.arenas\&.<i>\&.pdirty" (\fBsize_t\fR) r\-
1072
Number of pages within unused runs that are potentially dirty, and for which
1073
\fBmadvise\fR\fB\fI\&.\&.\&.\fR\fR\fB \fR\fB\fI\fBMADV_DONTNEED\fR\fR\fR
1074
or similar has not been called\&.
1077
"stats\&.arenas\&.<i>\&.mapped" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1079
Number of mapped bytes\&.
1082
"stats\&.arenas\&.<i>\&.npurge" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1084
Number of dirty page purge sweeps performed\&.
1087
"stats\&.arenas\&.<i>\&.nmadvise" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1090
\fBmadvise\fR\fB\fI\&.\&.\&.\fR\fR\fB \fR\fB\fI\fBMADV_DONTNEED\fR\fR\fR
1091
or similar calls made to purge dirty pages\&.
1094
"stats\&.arenas\&.<i>\&.npurged" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1096
Number of pages purged\&.
1099
"stats\&.arenas\&.<i>\&.small\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1101
Number of bytes currently allocated by small objects\&.
1104
"stats\&.arenas\&.<i>\&.small\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1106
Cumulative number of allocation requests served by small bins\&.
1109
"stats\&.arenas\&.<i>\&.small\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1111
Cumulative number of small objects returned to bins\&.
1114
"stats\&.arenas\&.<i>\&.small\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1116
Cumulative number of small allocation requests\&.
1119
"stats\&.arenas\&.<i>\&.large\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1121
Number of bytes currently allocated by large objects\&.
1124
"stats\&.arenas\&.<i>\&.large\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1126
Cumulative number of large allocation requests served directly by the arena\&.
1129
"stats\&.arenas\&.<i>\&.large\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1131
Cumulative number of large deallocation requests served directly by the arena\&.
1134
"stats\&.arenas\&.<i>\&.large\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1136
Cumulative number of large allocation requests\&.
1139
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.allocated" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1141
Current number of bytes allocated by bin\&.
1144
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1146
Cumulative number of allocations served by bin\&.
1149
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1151
Cumulative number of allocations returned to bin\&.
1154
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1156
Cumulative number of allocation requests\&.
1159
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.nfills" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR \fB\-\-enable\-tcache\fR]
1161
Cumulative number of tcache fills\&.
1164
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.nflushes" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR \fB\-\-enable\-tcache\fR]
1166
Cumulative number of tcache flushes\&.
1169
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.nruns" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1171
Cumulative number of runs created\&.
1174
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.nreruns" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1176
Cumulative number of times the current run from which to allocate changed\&.
1179
"stats\&.arenas\&.<i>\&.bins\&.<j>\&.curruns" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1181
Current number of runs\&.
1184
"stats\&.arenas\&.<i>\&.lruns\&.<j>\&.nmalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1186
Cumulative number of allocation requests for this size class served directly by the arena\&.
1189
"stats\&.arenas\&.<i>\&.lruns\&.<j>\&.ndalloc" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1191
Cumulative number of deallocation requests for this size class served directly by the arena\&.
1194
"stats\&.arenas\&.<i>\&.lruns\&.<j>\&.nrequests" (\fBuint64_t\fR) r\- [\fB\-\-enable\-stats\fR]
1196
Cumulative number of allocation requests for this size class\&.
1199
"stats\&.arenas\&.<i>\&.lruns\&.<j>\&.curruns" (\fBsize_t\fR) r\- [\fB\-\-enable\-stats\fR]
1201
Current number of runs for this size class\&.
1203
.SH "DEBUGGING MALLOC PROBLEMS"
1205
When debugging, it is a good idea to configure/build jemalloc with the
1206
\fB\-\-enable\-debug\fR
1208
\fB\-\-enable\-fill\fR
1209
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\&.
1211
Programs often accidentally depend on \(lquninitialized\(rq memory actually being filled with zero bytes\&. Junk filling (see the
1213
option) tends to expose such bugs in the form of obviously incorrect results and/or coredumps\&. Conversely, zero filling (see the
1215
option) eliminates the symptoms of such bugs\&. Between these two options, it is usually possible to quickly detect, diagnose, and eliminate such bugs\&.
1217
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
1218
\m[blue]\fBValgrind\fR\m[]\&\s-2\u[2]\d\s+2
1220
\fB\-\-enable\-valgrind\fR
1221
configuration option is enabled\&.
1222
.SH "DIAGNOSTIC MESSAGES"
1224
If any of the memory allocation/deallocation functions detect an error or warning condition, a message will be printed to file descriptor
1225
\fBSTDERR_FILENO\fR\&. Errors will result in the process dumping core\&. If the
1227
option is set, most warnings are treated as errors\&.
1230
\fImalloc_message\fR
1231
variable allows the programmer to override the function which emits the text strings forming the errors and warnings if for some reason the
1233
file descriptor is not suitable for this\&.
1234
\fBmalloc_message\fR\fB\fR
1237
pointer argument that is
1239
unless overridden by the arguments in a call to
1240
\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\&.
1242
All messages are prefixed by \(lq<jemalloc>:\(rq\&.
1250
functions return a pointer to the allocated memory if successful; otherwise a
1252
pointer is returned and
1258
\fBposix_memalign\fR\fB\fR
1259
function returns the value 0 if successful; otherwise it returns an error value\&. The
1260
\fBposix_memalign\fR\fB\fR
1261
function will fail if:
1267
parameter is not a power of 2 at least as large as
1268
sizeof(\fBvoid *\fR)\&.
1273
Memory allocation error\&.
1277
\fBaligned_alloc\fR\fB\fR
1278
function returns a pointer to the allocated memory if successful; otherwise a
1280
pointer is returned and
1283
\fBaligned_alloc\fR\fB\fR
1284
function will fail if:
1290
parameter is not a power of 2\&.
1295
Memory allocation error\&.
1300
function returns a pointer, possibly identical to
1301
\fIptr\fR, to the allocated memory if successful; otherwise a
1303
pointer is returned, and
1307
if the error was the result of an allocation failure\&. The
1309
function always leaves the original buffer intact when an error occurs\&.
1313
function returns no value\&.
1314
.SS "Non\-standard API"
1317
\fBmalloc_usable_size\fR\fB\fR
1318
function returns the usable size of the allocation pointed to by
1322
\fBmallctl\fR\fB\fR,
1323
\fBmallctlnametomib\fR\fB\fR, and
1324
\fBmallctlbymib\fR\fB\fR
1325
functions return 0 on success; otherwise they return an error value\&. The functions will fail if:
1333
is too large or too small\&. Alternatively,
1335
is too large or too small; in this case as much data as possible are read despite the error\&.
1341
is too short to hold the requested value\&.
1349
specifies an unknown/invalid value\&.
1354
Attempt to read or write void value, or attempt to write read\-only value\&.
1359
A memory allocation failure occurred\&.
1364
An interface with side effects failed in some way not directly related to
1365
\fBmallctl*\fR\fB\fR
1366
read/write processing\&.
1368
.SS "Experimental API"
1372
\fBrallocm\fR\fB\fR,
1373
\fBsallocm\fR\fB\fR,
1374
\fBdallocm\fR\fB\fR, and
1377
\fBALLOCM_SUCCESS\fR
1378
on success; otherwise they return an error value\&. The
1380
\fBrallocm\fR\fB\fR, and
1382
functions will fail if:
1386
Out of memory\&. Insufficient contiguous memory was available to service the allocation request\&. The
1388
function additionally sets
1391
\fBNULL\fR, whereas the
1399
function will also fail if:
1401
ALLOCM_ERR_NOT_MOVED
1403
\fBALLOCM_NO_MOVE\fR
1404
was specified, but the reallocation request could not be serviced without moving the object\&.
1408
The following environment variable affects the execution of the allocation functions:
1412
If the environment variable
1414
is set, the characters it contains will be interpreted as options\&.
1418
To dump core whenever a problem occurs:
1424
ln \-s \*(Aqabort:true\*(Aq /etc/malloc\&.conf
1430
To specify in the source a chunk size that is 16 MiB:
1436
malloc_conf = "lg_chunk:24";
1449
\fBgetpagesize\fR(3)
1455
\fBrealloc\fR\fB\fR, and
1457
functions conform to ISO/IEC 9899:1990 (\(lqISO C90\(rq)\&.
1460
\fBposix_memalign\fR\fB\fR
1461
function conforms to IEEE Std 1003\&.1\-2001 (\(lqPOSIX\&.1\(rq)\&.
1471
\%http://www.canonware.com/jemalloc/
1476
\%http://valgrind.org/
1481
\%http://code.google.com/p/gperftools/
added
removed
extra/jemalloc/doc/jemalloc.3
