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diff --git a/memory/jemalloc/src/doc/jemalloc.xml.in b/memory/jemalloc/src/doc/jemalloc.xml.in new file mode 100644 index 000000000..3d2e721d3 --- /dev/null +++ b/memory/jemalloc/src/doc/jemalloc.xml.in @@ -0,0 +1,2966 @@ +<?xml version='1.0' encoding='UTF-8'?> +<?xml-stylesheet type="text/xsl" + href="http://docbook.sourceforge.net/release/xsl/current/manpages/docbook.xsl"?> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" + "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [ +]> + +<refentry> + <refentryinfo> + <title>User Manual</title> + <productname>jemalloc</productname> + <releaseinfo role="version">@jemalloc_version@</releaseinfo> + <authorgroup> + <author> + <firstname>Jason</firstname> + <surname>Evans</surname> + <personblurb>Author</personblurb> + </author> + </authorgroup> + </refentryinfo> + <refmeta> + <refentrytitle>JEMALLOC</refentrytitle> + <manvolnum>3</manvolnum> + </refmeta> + <refnamediv> + <refdescriptor>jemalloc</refdescriptor> + <refname>jemalloc</refname> + <!-- Each refname causes a man page file to be created. Only if this were + the system malloc(3) implementation would these files be appropriate. + <refname>malloc</refname> + <refname>calloc</refname> + <refname>posix_memalign</refname> + <refname>aligned_alloc</refname> + <refname>realloc</refname> + <refname>free</refname> + <refname>mallocx</refname> + <refname>rallocx</refname> + <refname>xallocx</refname> + <refname>sallocx</refname> + <refname>dallocx</refname> + <refname>sdallocx</refname> + <refname>nallocx</refname> + <refname>mallctl</refname> + <refname>mallctlnametomib</refname> + <refname>mallctlbymib</refname> + <refname>malloc_stats_print</refname> + <refname>malloc_usable_size</refname> + --> + <refpurpose>general purpose memory allocation functions</refpurpose> + </refnamediv> + <refsect1 id="library"> + <title>LIBRARY</title> + <para>This manual describes jemalloc @jemalloc_version@. More information + can be found at the <ulink + url="http://jemalloc.net/">jemalloc website</ulink>.</para> + </refsect1> + <refsynopsisdiv> + <title>SYNOPSIS</title> + <funcsynopsis> + <funcsynopsisinfo>#include <<filename class="headerfile">jemalloc/jemalloc.h</filename>></funcsynopsisinfo> + <refsect2> + <title>Standard API</title> + <funcprototype> + <funcdef>void *<function>malloc</function></funcdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void *<function>calloc</function></funcdef> + <paramdef>size_t <parameter>number</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>int <function>posix_memalign</function></funcdef> + <paramdef>void **<parameter>ptr</parameter></paramdef> + <paramdef>size_t <parameter>alignment</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void *<function>aligned_alloc</function></funcdef> + <paramdef>size_t <parameter>alignment</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void *<function>realloc</function></funcdef> + <paramdef>void *<parameter>ptr</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void <function>free</function></funcdef> + <paramdef>void *<parameter>ptr</parameter></paramdef> + </funcprototype> + </refsect2> + <refsect2> + <title>Non-standard API</title> + <funcprototype> + <funcdef>void *<function>mallocx</function></funcdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void *<function>rallocx</function></funcdef> + <paramdef>void *<parameter>ptr</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>size_t <function>xallocx</function></funcdef> + <paramdef>void *<parameter>ptr</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>size_t <parameter>extra</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>size_t <function>sallocx</function></funcdef> + <paramdef>void *<parameter>ptr</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void <function>dallocx</function></funcdef> + <paramdef>void *<parameter>ptr</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void <function>sdallocx</function></funcdef> + <paramdef>void *<parameter>ptr</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>size_t <function>nallocx</function></funcdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>int <parameter>flags</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>int <function>mallctl</function></funcdef> + <paramdef>const char *<parameter>name</parameter></paramdef> + <paramdef>void *<parameter>oldp</parameter></paramdef> + <paramdef>size_t *<parameter>oldlenp</parameter></paramdef> + <paramdef>void *<parameter>newp</parameter></paramdef> + <paramdef>size_t <parameter>newlen</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>int <function>mallctlnametomib</function></funcdef> + <paramdef>const char *<parameter>name</parameter></paramdef> + <paramdef>size_t *<parameter>mibp</parameter></paramdef> + <paramdef>size_t *<parameter>miblenp</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>int <function>mallctlbymib</function></funcdef> + <paramdef>const size_t *<parameter>mib</parameter></paramdef> + <paramdef>size_t <parameter>miblen</parameter></paramdef> + <paramdef>void *<parameter>oldp</parameter></paramdef> + <paramdef>size_t *<parameter>oldlenp</parameter></paramdef> + <paramdef>void *<parameter>newp</parameter></paramdef> + <paramdef>size_t <parameter>newlen</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void <function>malloc_stats_print</function></funcdef> + <paramdef>void <parameter>(*write_cb)</parameter> + <funcparams>void *, const char *</funcparams> + </paramdef> + <paramdef>void *<parameter>cbopaque</parameter></paramdef> + <paramdef>const char *<parameter>opts</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>size_t <function>malloc_usable_size</function></funcdef> + <paramdef>const void *<parameter>ptr</parameter></paramdef> + </funcprototype> + <funcprototype> + <funcdef>void <function>(*malloc_message)</function></funcdef> + <paramdef>void *<parameter>cbopaque</parameter></paramdef> + <paramdef>const char *<parameter>s</parameter></paramdef> + </funcprototype> + <para><type>const char *</type><varname>malloc_conf</varname>;</para> + </refsect2> + </funcsynopsis> + </refsynopsisdiv> + <refsect1 id="description"> + <title>DESCRIPTION</title> + <refsect2> + <title>Standard API</title> + + <para>The <function>malloc()</function> function allocates + <parameter>size</parameter> bytes of uninitialized memory. The allocated + space is suitably aligned (after possible pointer coercion) for storage + of any type of object.</para> + + <para>The <function>calloc()</function> function allocates + space for <parameter>number</parameter> objects, each + <parameter>size</parameter> bytes in length. The result is identical to + calling <function>malloc()</function> with an argument of + <parameter>number</parameter> * <parameter>size</parameter>, with the + exception that the allocated memory is explicitly initialized to zero + bytes.</para> + + <para>The <function>posix_memalign()</function> function + allocates <parameter>size</parameter> bytes of memory such that the + allocation's base address is a multiple of + <parameter>alignment</parameter>, and returns the allocation in the value + pointed to by <parameter>ptr</parameter>. The requested + <parameter>alignment</parameter> must be a power of 2 at least as large as + <code language="C">sizeof(<type>void *</type>)</code>.</para> + + <para>The <function>aligned_alloc()</function> function + allocates <parameter>size</parameter> bytes of memory such that the + allocation's base address is a multiple of + <parameter>alignment</parameter>. The requested + <parameter>alignment</parameter> must be a power of 2. Behavior is + undefined if <parameter>size</parameter> is not an integral multiple of + <parameter>alignment</parameter>.</para> + + <para>The <function>realloc()</function> function changes the + size of the previously allocated memory referenced by + <parameter>ptr</parameter> to <parameter>size</parameter> 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 <parameter>ptr</parameter> is freed and a pointer to the newly + allocated memory is returned. Note that + <function>realloc()</function> may move the memory allocation, + resulting in a different return value than <parameter>ptr</parameter>. + If <parameter>ptr</parameter> is <constant>NULL</constant>, the + <function>realloc()</function> function behaves identically to + <function>malloc()</function> for the specified size.</para> + + <para>The <function>free()</function> function causes the + allocated memory referenced by <parameter>ptr</parameter> to be made + available for future allocations. If <parameter>ptr</parameter> is + <constant>NULL</constant>, no action occurs.</para> + </refsect2> + <refsect2> + <title>Non-standard API</title> + <para>The <function>mallocx()</function>, + <function>rallocx()</function>, + <function>xallocx()</function>, + <function>sallocx()</function>, + <function>dallocx()</function>, + <function>sdallocx()</function>, and + <function>nallocx()</function> functions all have a + <parameter>flags</parameter> argument that can be used to specify + options. The functions only check the options that are contextually + relevant. Use bitwise or (<code language="C">|</code>) operations to + specify one or more of the following: + <variablelist> + <varlistentry id="MALLOCX_LG_ALIGN"> + <term><constant>MALLOCX_LG_ALIGN(<parameter>la</parameter>) + </constant></term> + + <listitem><para>Align the memory allocation to start at an address + that is a multiple of <code language="C">(1 << + <parameter>la</parameter>)</code>. This macro does not validate + that <parameter>la</parameter> is within the valid + range.</para></listitem> + </varlistentry> + <varlistentry id="MALLOCX_ALIGN"> + <term><constant>MALLOCX_ALIGN(<parameter>a</parameter>) + </constant></term> + + <listitem><para>Align the memory allocation to start at an address + that is a multiple of <parameter>a</parameter>, where + <parameter>a</parameter> is a power of two. This macro does not + validate that <parameter>a</parameter> is a power of 2. + </para></listitem> + </varlistentry> + <varlistentry id="MALLOCX_ZERO"> + <term><constant>MALLOCX_ZERO</constant></term> + + <listitem><para>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.</para></listitem> + </varlistentry> + <varlistentry id="MALLOCX_TCACHE"> + <term><constant>MALLOCX_TCACHE(<parameter>tc</parameter>) + </constant></term> + + <listitem><para>Use the thread-specific cache (tcache) specified by + the identifier <parameter>tc</parameter>, which must have been + acquired via the <link + linkend="tcache.create"><mallctl>tcache.create</mallctl></link> + mallctl. This macro does not validate that + <parameter>tc</parameter> specifies a valid + identifier.</para></listitem> + </varlistentry> + <varlistentry id="MALLOC_TCACHE_NONE"> + <term><constant>MALLOCX_TCACHE_NONE</constant></term> + + <listitem><para>Do not use a thread-specific cache (tcache). Unless + <constant>MALLOCX_TCACHE(<parameter>tc</parameter>)</constant> or + <constant>MALLOCX_TCACHE_NONE</constant> is specified, an + automatically managed tcache will be used under many circumstances. + This macro cannot be used in the same <parameter>flags</parameter> + argument as + <constant>MALLOCX_TCACHE(<parameter>tc</parameter>)</constant>.</para></listitem> + </varlistentry> + <varlistentry id="MALLOCX_ARENA"> + <term><constant>MALLOCX_ARENA(<parameter>a</parameter>) + </constant></term> + + <listitem><para>Use the arena specified by the index + <parameter>a</parameter>. This macro has no effect for regions that + were allocated via an arena other than the one specified. This + macro does not validate that <parameter>a</parameter> specifies an + arena index in the valid range.</para></listitem> + </varlistentry> + </variablelist> + </para> + + <para>The <function>mallocx()</function> function allocates at + least <parameter>size</parameter> bytes of memory, and returns a pointer + to the base address of the allocation. Behavior is undefined if + <parameter>size</parameter> is <constant>0</constant>.</para> + + <para>The <function>rallocx()</function> function resizes the + allocation at <parameter>ptr</parameter> to be at least + <parameter>size</parameter> 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 + <parameter>size</parameter> is <constant>0</constant>.</para> + + <para>The <function>xallocx()</function> function resizes the + allocation at <parameter>ptr</parameter> in place to be at least + <parameter>size</parameter> bytes, and returns the real size of the + allocation. If <parameter>extra</parameter> is non-zero, an attempt is + made to resize the allocation to be at least <code + language="C">(<parameter>size</parameter> + + <parameter>extra</parameter>)</code> bytes, though inability to allocate + the extra byte(s) will not by itself result in failure to resize. + Behavior is undefined if <parameter>size</parameter> is + <constant>0</constant>, or if <code + language="C">(<parameter>size</parameter> + <parameter>extra</parameter> + > <constant>SIZE_T_MAX</constant>)</code>.</para> + + <para>The <function>sallocx()</function> function returns the + real size of the allocation at <parameter>ptr</parameter>.</para> + + <para>The <function>dallocx()</function> function causes the + memory referenced by <parameter>ptr</parameter> to be made available for + future allocations.</para> + + <para>The <function>sdallocx()</function> function is an + extension of <function>dallocx()</function> with a + <parameter>size</parameter> parameter to allow the caller to pass in the + allocation size as an optimization. The minimum valid input size is the + original requested size of the allocation, and the maximum valid input + size is the corresponding value returned by + <function>nallocx()</function> or + <function>sallocx()</function>.</para> + + <para>The <function>nallocx()</function> function allocates no + memory, but it performs the same size computation as the + <function>mallocx()</function> function, and returns the real + size of the allocation that would result from the equivalent + <function>mallocx()</function> function call, or + <constant>0</constant> if the inputs exceed the maximum supported size + class and/or alignment. Behavior is undefined if + <parameter>size</parameter> is <constant>0</constant>.</para> + + <para>The <function>mallctl()</function> function provides a + general interface for introspecting the memory allocator, as well as + setting modifiable parameters and triggering actions. The + period-separated <parameter>name</parameter> argument specifies a + location in a tree-structured namespace; see the <xref + linkend="mallctl_namespace" xrefstyle="template:%t"/> section for + documentation on the tree contents. To read a value, pass a pointer via + <parameter>oldp</parameter> to adequate space to contain the value, and a + pointer to its length via <parameter>oldlenp</parameter>; otherwise pass + <constant>NULL</constant> and <constant>NULL</constant>. Similarly, to + write a value, pass a pointer to the value via + <parameter>newp</parameter>, and its length via + <parameter>newlen</parameter>; otherwise pass <constant>NULL</constant> + and <constant>0</constant>.</para> + + <para>The <function>mallctlnametomib()</function> 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 <quote>Management Information Base</quote> (MIB) that can be passed + repeatedly to <function>mallctlbymib()</function>. Upon + successful return from <function>mallctlnametomib()</function>, + <parameter>mibp</parameter> contains an array of + <parameter>*miblenp</parameter> integers, where + <parameter>*miblenp</parameter> is the lesser of the number of components + in <parameter>name</parameter> and the input value of + <parameter>*miblenp</parameter>. Thus it is possible to pass a + <parameter>*miblenp</parameter> 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 + <link + linkend="arenas.bin.i.size"><mallctl>arenas.bin.2.size</mallctl></link>), + the corresponding MIB component will always be that integer. Therefore, + it is legitimate to construct code like the following: <programlisting + language="C"><![CDATA[ +unsigned nbins, i; +size_t mib[4]; +size_t len, miblen; + +len = sizeof(nbins); +mallctl("arenas.nbins", &nbins, &len, NULL, 0); + +miblen = 4; +mallctlnametomib("arenas.bin.0.size", mib, &miblen); +for (i = 0; i < nbins; i++) { + size_t bin_size; + + mib[2] = i; + len = sizeof(bin_size); + mallctlbymib(mib, miblen, &bin_size, &len, NULL, 0); + /* Do something with bin_size... */ +}]]></programlisting></para> + + <para>The <function>malloc_stats_print()</function> function writes + summary statistics via the <parameter>write_cb</parameter> callback + function pointer and <parameter>cbopaque</parameter> data passed to + <parameter>write_cb</parameter>, or <function>malloc_message()</function> + if <parameter>write_cb</parameter> is <constant>NULL</constant>. The + statistics are presented in human-readable form unless <quote>J</quote> is + specified as a character within the <parameter>opts</parameter> string, in + which case the statistics are presented in <ulink + url="http://www.json.org/">JSON format</ulink>. This function can be + called repeatedly. General information that never changes during + execution can be omitted by specifying <quote>g</quote> as a character + within the <parameter>opts</parameter> string. Note that + <function>malloc_message()</function> uses the + <function>mallctl*()</function> functions internally, so inconsistent + statistics can be reported if multiple threads use these functions + simultaneously. If <option>--enable-stats</option> is specified during + configuration, <quote>m</quote> and <quote>a</quote> can be specified to + omit merged arena and per arena statistics, respectively; + <quote>b</quote>, <quote>l</quote>, and <quote>h</quote> can be specified + to omit per size class statistics for bins, large objects, and huge + 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.</para> + + <para>The <function>malloc_usable_size()</function> function + returns the usable size of the allocation pointed to by + <parameter>ptr</parameter>. The return value may be larger than the size + that was requested during allocation. The + <function>malloc_usable_size()</function> function is not a + mechanism for in-place <function>realloc()</function>; rather + it is provided solely as a tool for introspection purposes. Any + discrepancy between the requested allocation size and the size reported + by <function>malloc_usable_size()</function> should not be + depended on, since such behavior is entirely implementation-dependent. + </para> + </refsect2> + </refsect1> + <refsect1 id="tuning"> + <title>TUNING</title> + <para>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.</para> + + <para>The string specified via <option>--with-malloc-conf</option>, the + string pointed to by the global variable <varname>malloc_conf</varname>, the + <quote>name</quote> of the file referenced by the symbolic link named + <filename class="symlink">/etc/malloc.conf</filename>, and the value of the + environment variable <envar>MALLOC_CONF</envar>, will be interpreted, in + that order, from left to right as options. Note that + <varname>malloc_conf</varname> may be read before + <function>main()</function> is entered, so the declaration of + <varname>malloc_conf</varname> should specify an initializer that contains + the final value to be read by jemalloc. <option>--with-malloc-conf</option> + and <varname>malloc_conf</varname> are compile-time mechanisms, whereas + <filename class="symlink">/etc/malloc.conf</filename> and + <envar>MALLOC_CONF</envar> can be safely set any time prior to program + invocation.</para> + + <para>An options string is a comma-separated list of option:value pairs. + There is one key corresponding to each <link + linkend="opt.abort"><mallctl>opt.*</mallctl></link> mallctl (see the <xref + linkend="mallctl_namespace" xrefstyle="template:%t"/> section for options + documentation). For example, <literal>abort:true,narenas:1</literal> sets + the <link linkend="opt.abort"><mallctl>opt.abort</mallctl></link> and <link + linkend="opt.narenas"><mallctl>opt.narenas</mallctl></link> 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.</para> + </refsect1> + <refsect1 id="implementation_notes"> + <title>IMPLEMENTATION NOTES</title> + <para>Traditionally, allocators have used + <citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> to obtain memory, which is + suboptimal for several reasons, including race conditions, increased + fragmentation, and artificial limitations on maximum usable memory. If + <citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> is supported by the operating + system, this allocator uses both + <citerefentry><refentrytitle>mmap</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> and + <citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>, in that order of preference; + otherwise only <citerefentry><refentrytitle>mmap</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> is used.</para> + + <para>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.</para> + + <para>In addition to multiple arenas, unless + <option>--disable-tcache</option> 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.</para> + + <para>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. User objects are + broken into three categories according to size: small, large, and huge. + Multiple small and large objects can reside within a single chunk, whereas + huge objects each have one or more chunks backing them. Each chunk that + contains small and/or large objects 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.</para> + + <para>Small objects are managed in groups by page runs. Each run maintains + a bitmap 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 <code + language="C">sizeof(<type>double</type>)</code>. All other object size + classes are multiples of the quantum, spaced such that there are four size + classes for each doubling in size, which limits internal fragmentation to + approximately 20% for all but the smallest size classes. Small size classes + are smaller than four times the page size, large size classes are smaller + than the chunk size (see the <link + linkend="opt.lg_chunk"><mallctl>opt.lg_chunk</mallctl></link> option), and + huge size classes extend from the chunk size up to the largest size class + that does not exceed <constant>PTRDIFF_MAX</constant>.</para> + + <para>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.</para> + + <para>The <function>realloc()</function>, + <function>rallocx()</function>, and + <function>xallocx()</function> functions may resize allocations + without moving them under limited circumstances. Unlike the + <function>*allocx()</function> API, the standard API does not + officially round up the usable size of an allocation to the nearest size + class, so technically it is necessary to call + <function>realloc()</function> to grow e.g. a 9-byte allocation to + 16 bytes, or shrink a 16-byte allocation to 9 bytes. Growth and shrinkage + trivially succeeds in place as long as the pre-size and post-size both round + up to the same size class. No other API guarantees are made regarding + in-place resizing, but the current implementation also tries to resize large + and huge allocations in place, as long as the pre-size and post-size are + both large or both huge. In such cases shrinkage always succeeds for large + size classes, but for huge size classes the chunk allocator must support + splitting (see <link + linkend="arena.i.chunk_hooks"><mallctl>arena.<i>.chunk_hooks</mallctl></link>). + Growth only succeeds if the trailing memory is currently available, and + additionally for huge size classes the chunk allocator must support + merging.</para> + + <para>Assuming 2 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 <xref + linkend="size_classes" xrefstyle="template:Table %n"/>.</para> + + <table xml:id="size_classes" frame="all"> + <title>Size classes</title> + <tgroup cols="3" colsep="1" rowsep="1"> + <colspec colname="c1" align="left"/> + <colspec colname="c2" align="right"/> + <colspec colname="c3" align="left"/> + <thead> + <row> + <entry>Category</entry> + <entry>Spacing</entry> + <entry>Size</entry> + </row> + </thead> + <tbody> + <row> + <entry morerows="8">Small</entry> + <entry>lg</entry> + <entry>[8]</entry> + </row> + <row> + <entry>16</entry> + <entry>[16, 32, 48, 64, 80, 96, 112, 128]</entry> + </row> + <row> + <entry>32</entry> + <entry>[160, 192, 224, 256]</entry> + </row> + <row> + <entry>64</entry> + <entry>[320, 384, 448, 512]</entry> + </row> + <row> + <entry>128</entry> + <entry>[640, 768, 896, 1024]</entry> + </row> + <row> + <entry>256</entry> + <entry>[1280, 1536, 1792, 2048]</entry> + </row> + <row> + <entry>512</entry> + <entry>[2560, 3072, 3584, 4096]</entry> + </row> + <row> + <entry>1 KiB</entry> + <entry>[5 KiB, 6 KiB, 7 KiB, 8 KiB]</entry> + </row> + <row> + <entry>2 KiB</entry> + <entry>[10 KiB, 12 KiB, 14 KiB]</entry> + </row> + <row> + <entry morerows="7">Large</entry> + <entry>2 KiB</entry> + <entry>[16 KiB]</entry> + </row> + <row> + <entry>4 KiB</entry> + <entry>[20 KiB, 24 KiB, 28 KiB, 32 KiB]</entry> + </row> + <row> + <entry>8 KiB</entry> + <entry>[40 KiB, 48 KiB, 54 KiB, 64 KiB]</entry> + </row> + <row> + <entry>16 KiB</entry> + <entry>[80 KiB, 96 KiB, 112 KiB, 128 KiB]</entry> + </row> + <row> + <entry>32 KiB</entry> + <entry>[160 KiB, 192 KiB, 224 KiB, 256 KiB]</entry> + </row> + <row> + <entry>64 KiB</entry> + <entry>[320 KiB, 384 KiB, 448 KiB, 512 KiB]</entry> + </row> + <row> + <entry>128 KiB</entry> + <entry>[640 KiB, 768 KiB, 896 KiB, 1 MiB]</entry> + </row> + <row> + <entry>256 KiB</entry> + <entry>[1280 KiB, 1536 KiB, 1792 KiB]</entry> + </row> + <row> + <entry morerows="8">Huge</entry> + <entry>256 KiB</entry> + <entry>[2 MiB]</entry> + </row> + <row> + <entry>512 KiB</entry> + <entry>[2560 KiB, 3 MiB, 3584 KiB, 4 MiB]</entry> + </row> + <row> + <entry>1 MiB</entry> + <entry>[5 MiB, 6 MiB, 7 MiB, 8 MiB]</entry> + </row> + <row> + <entry>2 MiB</entry> + <entry>[10 MiB, 12 MiB, 14 MiB, 16 MiB]</entry> + </row> + <row> + <entry>4 MiB</entry> + <entry>[20 MiB, 24 MiB, 28 MiB, 32 MiB]</entry> + </row> + <row> + <entry>8 MiB</entry> + <entry>[40 MiB, 48 MiB, 56 MiB, 64 MiB]</entry> + </row> + <row> + <entry>...</entry> + <entry>...</entry> + </row> + <row> + <entry>512 PiB</entry> + <entry>[2560 PiB, 3 EiB, 3584 PiB, 4 EiB]</entry> + </row> + <row> + <entry>1 EiB</entry> + <entry>[5 EiB, 6 EiB, 7 EiB]</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + <refsect1 id="mallctl_namespace"> + <title>MALLCTL NAMESPACE</title> + <para>The following names are defined in the namespace accessible via the + <function>mallctl*()</function> functions. Value types are + specified in parentheses, their readable/writable statuses are encoded as + <literal>rw</literal>, <literal>r-</literal>, <literal>-w</literal>, or + <literal>--</literal>, and required build configuration flags follow, if + any. A name element encoded as <literal><i></literal> or + <literal><j></literal> indicates an integer component, where the + integer varies from 0 to some upper value that must be determined via + introspection. In the case of <mallctl>stats.arenas.<i>.*</mallctl>, + <literal><i></literal> equal to <link + linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link> can be + used to access the summation of statistics from all arenas. Take special + note of the <link linkend="epoch"><mallctl>epoch</mallctl></link> mallctl, + which controls refreshing of cached dynamic statistics.</para> + + <variablelist> + <varlistentry id="version"> + <term> + <mallctl>version</mallctl> + (<type>const char *</type>) + <literal>r-</literal> + </term> + <listitem><para>Return the jemalloc version string.</para></listitem> + </varlistentry> + + <varlistentry id="epoch"> + <term> + <mallctl>epoch</mallctl> + (<type>uint64_t</type>) + <literal>rw</literal> + </term> + <listitem><para>If a value is passed in, refresh the data from which + the <function>mallctl*()</function> functions report values, + and increment the epoch. Return the current epoch. This is useful for + detecting whether another thread caused a refresh.</para></listitem> + </varlistentry> + + <varlistentry id="config.cache_oblivious"> + <term> + <mallctl>config.cache_oblivious</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-cache-oblivious</option> was specified + during build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.debug"> + <term> + <mallctl>config.debug</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-debug</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.fill"> + <term> + <mallctl>config.fill</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-fill</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.lazy_lock"> + <term> + <mallctl>config.lazy_lock</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-lazy-lock</option> was specified + during build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.malloc_conf"> + <term> + <mallctl>config.malloc_conf</mallctl> + (<type>const char *</type>) + <literal>r-</literal> + </term> + <listitem><para>Embedded configure-time-specified run-time options + string, empty unless <option>--with-malloc-conf</option> was specified + during build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.munmap"> + <term> + <mallctl>config.munmap</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-munmap</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.prof"> + <term> + <mallctl>config.prof</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-prof</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.prof_libgcc"> + <term> + <mallctl>config.prof_libgcc</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--disable-prof-libgcc</option> was not + specified during build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.prof_libunwind"> + <term> + <mallctl>config.prof_libunwind</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-prof-libunwind</option> was specified + during build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.stats"> + <term> + <mallctl>config.stats</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-stats</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.tcache"> + <term> + <mallctl>config.tcache</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--disable-tcache</option> was not specified + during build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.tls"> + <term> + <mallctl>config.tls</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--disable-tls</option> was not specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.utrace"> + <term> + <mallctl>config.utrace</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-utrace</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.valgrind"> + <term> + <mallctl>config.valgrind</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-valgrind</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="config.xmalloc"> + <term> + <mallctl>config.xmalloc</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para><option>--enable-xmalloc</option> was specified during + build configuration.</para></listitem> + </varlistentry> + + <varlistentry id="opt.abort"> + <term> + <mallctl>opt.abort</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para>Abort-on-warning enabled/disabled. If true, most + warnings are fatal. The process will call + <citerefentry><refentrytitle>abort</refentrytitle> + <manvolnum>3</manvolnum></citerefentry> in these cases. This option is + disabled by default unless <option>--enable-debug</option> is + specified during configuration, in which case it is enabled by default. + </para></listitem> + </varlistentry> + + <varlistentry id="opt.dss"> + <term> + <mallctl>opt.dss</mallctl> + (<type>const char *</type>) + <literal>r-</literal> + </term> + <listitem><para>dss (<citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>) allocation precedence as + related to <citerefentry><refentrytitle>mmap</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> allocation. The following + settings are supported if + <citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> is supported by the operating + system: <quote>disabled</quote>, <quote>primary</quote>, and + <quote>secondary</quote>; otherwise only <quote>disabled</quote> is + supported. The default is <quote>secondary</quote> if + <citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> is supported by the operating + system; <quote>disabled</quote> otherwise. + </para></listitem> + </varlistentry> + + <varlistentry id="opt.lg_chunk"> + <term> + <mallctl>opt.lg_chunk</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>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 2 MiB (2^21). + </para></listitem> + </varlistentry> + + <varlistentry id="opt.narenas"> + <term> + <mallctl>opt.narenas</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + </term> + <listitem><para>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.</para></listitem> + </varlistentry> + + <varlistentry id="opt.purge"> + <term> + <mallctl>opt.purge</mallctl> + (<type>const char *</type>) + <literal>r-</literal> + </term> + <listitem><para>Purge mode is “ratio” (default) or + “decay”. See <link + linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> + for details of the ratio mode. See <link + linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for + details of the decay mode.</para></listitem> + </varlistentry> + + <varlistentry id="opt.lg_dirty_mult"> + <term> + <mallctl>opt.lg_dirty_mult</mallctl> + (<type>ssize_t</type>) + <literal>r-</literal> + </term> + <listitem><para>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 <citerefentry><refentrytitle>madvise</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> 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. See <link + linkend="arenas.lg_dirty_mult"><mallctl>arenas.lg_dirty_mult</mallctl></link> + and <link + linkend="arena.i.lg_dirty_mult"><mallctl>arena.<i>.lg_dirty_mult</mallctl></link> + for related dynamic control options.</para></listitem> + </varlistentry> + + <varlistentry id="opt.decay_time"> + <term> + <mallctl>opt.decay_time</mallctl> + (<type>ssize_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Approximate time in seconds from the creation of a set + of unused dirty pages until an equivalent set of unused dirty pages is + purged and/or reused. The pages are incrementally purged according to a + sigmoidal decay curve that starts and ends with zero purge rate. A + decay time of 0 causes all unused dirty pages to be purged immediately + upon creation. A decay time of -1 disables purging. The default decay + time is 10 seconds. See <link + linkend="arenas.decay_time"><mallctl>arenas.decay_time</mallctl></link> + and <link + linkend="arena.i.decay_time"><mallctl>arena.<i>.decay_time</mallctl></link> + for related dynamic control options. + </para></listitem> + </varlistentry> + + <varlistentry id="opt.stats_print"> + <term> + <mallctl>opt.stats_print</mallctl> + (<type>bool</type>) + <literal>r-</literal> + </term> + <listitem><para>Enable/disable statistics printing at exit. If + enabled, the <function>malloc_stats_print()</function> + function is called at program exit via an + <citerefentry><refentrytitle>atexit</refentrytitle> + <manvolnum>3</manvolnum></citerefentry> function. If + <option>--enable-stats</option> 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. Furthermore, <function>atexit()</function> may + allocate memory during application initialization and then deadlock + internally when jemalloc in turn calls + <function>atexit()</function>, so this option is not + universally usable (though the application can register its own + <function>atexit()</function> function with equivalent + functionality). 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.</para></listitem> + </varlistentry> + + <varlistentry id="opt.junk"> + <term> + <mallctl>opt.junk</mallctl> + (<type>const char *</type>) + <literal>r-</literal> + [<option>--enable-fill</option>] + </term> + <listitem><para>Junk filling. If set to <quote>alloc</quote>, each byte + of uninitialized allocated memory will be initialized to + <literal>0xa5</literal>. If set to <quote>free</quote>, all deallocated + memory will be initialized to <literal>0x5a</literal>. If set to + <quote>true</quote>, both allocated and deallocated memory will be + initialized, and if set to <quote>false</quote>, junk filling be + disabled entirely. This is intended for debugging and will impact + performance negatively. This option is <quote>false</quote> by default + unless <option>--enable-debug</option> is specified during + configuration, in which case it is <quote>true</quote> by default unless + running inside <ulink + url="http://valgrind.org/">Valgrind</ulink>.</para></listitem> + </varlistentry> + + <varlistentry id="opt.quarantine"> + <term> + <mallctl>opt.quarantine</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-fill</option>] + </term> + <listitem><para>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 <link + linkend="opt.junk"><mallctl>opt.junk</mallctl></link> option is + enabled. This feature is of particular use in combination with <ulink + url="http://valgrind.org/">Valgrind</ulink>, 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.</para></listitem> + </varlistentry> + + <varlistentry id="opt.redzone"> + <term> + <mallctl>opt.redzone</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-fill</option>] + </term> + <listitem><para>Redzones enabled/disabled. If enabled, small + allocations have redzones before and after them. Furthermore, if the + <link linkend="opt.junk"><mallctl>opt.junk</mallctl></link> 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 <ulink url="http://valgrind.org/">Valgrind</ulink>, + 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.</para></listitem> + </varlistentry> + + <varlistentry id="opt.zero"> + <term> + <mallctl>opt.zero</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-fill</option>] + </term> + <listitem><para>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 + <function>realloc()</function> and + <function>rallocx()</function> 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. + </para></listitem> + </varlistentry> + + <varlistentry id="opt.utrace"> + <term> + <mallctl>opt.utrace</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-utrace</option>] + </term> + <listitem><para>Allocation tracing based on + <citerefentry><refentrytitle>utrace</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> enabled/disabled. This option + is disabled by default.</para></listitem> + </varlistentry> + + <varlistentry id="opt.xmalloc"> + <term> + <mallctl>opt.xmalloc</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-xmalloc</option>] + </term> + <listitem><para>Abort-on-out-of-memory enabled/disabled. If enabled, + rather than returning failure for any allocation function, display a + diagnostic message on <constant>STDERR_FILENO</constant> and cause the + program to drop core (using + <citerefentry><refentrytitle>abort</refentrytitle> + <manvolnum>3</manvolnum></citerefentry>). If an application is + designed to depend on this behavior, set the option at compile time by + including the following in the source code: + <programlisting language="C"><![CDATA[ +malloc_conf = "xmalloc:true";]]></programlisting> + This option is disabled by default.</para></listitem> + </varlistentry> + + <varlistentry id="opt.tcache"> + <term> + <mallctl>opt.tcache</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Thread-specific caching (tcache) enabled/disabled. When + there are multiple threads, each thread uses a tcache 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 <link + linkend="opt.lg_tcache_max"><mallctl>opt.lg_tcache_max</mallctl></link> + option for related tuning information. This option is enabled by + default unless running inside <ulink + url="http://valgrind.org/">Valgrind</ulink>, in which case it is + forcefully disabled.</para></listitem> + </varlistentry> + + <varlistentry id="opt.lg_tcache_max"> + <term> + <mallctl>opt.lg_tcache_max</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Maximum size class (log base 2) to cache in the + thread-specific cache (tcache). 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).</para></listitem> + </varlistentry> + + <varlistentry id="opt.prof"> + <term> + <mallctl>opt.prof</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Memory profiling enabled/disabled. If enabled, profile + memory allocation activity. See the <link + linkend="opt.prof_active"><mallctl>opt.prof_active</mallctl></link> + option for on-the-fly activation/deactivation. See the <link + linkend="opt.lg_prof_sample"><mallctl>opt.lg_prof_sample</mallctl></link> + option for probabilistic sampling control. See the <link + linkend="opt.prof_accum"><mallctl>opt.prof_accum</mallctl></link> + option for control of cumulative sample reporting. See the <link + linkend="opt.lg_prof_interval"><mallctl>opt.lg_prof_interval</mallctl></link> + option for information on interval-triggered profile dumping, the <link + linkend="opt.prof_gdump"><mallctl>opt.prof_gdump</mallctl></link> + option for information on high-water-triggered profile dumping, and the + <link linkend="opt.prof_final"><mallctl>opt.prof_final</mallctl></link> + option for final profile dumping. Profile output is compatible with + the <command>jeprof</command> command, which is based on the + <command>pprof</command> that is developed as part of the <ulink + url="http://code.google.com/p/gperftools/">gperftools + package</ulink>. See <link linkend="heap_profile_format">HEAP PROFILE + FORMAT</link> for heap profile format documentation.</para></listitem> + </varlistentry> + + <varlistentry id="opt.prof_prefix"> + <term> + <mallctl>opt.prof_prefix</mallctl> + (<type>const char *</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>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 + <filename>jeprof</filename>.</para></listitem> + </varlistentry> + + <varlistentry id="opt.prof_active"> + <term> + <mallctl>opt.prof_active</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Profiling activated/deactivated. This is a secondary + control mechanism that makes it possible to start the application with + profiling enabled (see the <link + linkend="opt.prof"><mallctl>opt.prof</mallctl></link> option) but + inactive, then toggle profiling at any time during program execution + with the <link + linkend="prof.active"><mallctl>prof.active</mallctl></link> mallctl. + This option is enabled by default.</para></listitem> + </varlistentry> + + <varlistentry id="opt.prof_thread_active_init"> + <term> + <mallctl>opt.prof_thread_active_init</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Initial setting for <link + linkend="thread.prof.active"><mallctl>thread.prof.active</mallctl></link> + in newly created threads. The initial setting for newly created threads + can also be changed during execution via the <link + linkend="prof.thread_active_init"><mallctl>prof.thread_active_init</mallctl></link> + mallctl. This option is enabled by default.</para></listitem> + </varlistentry> + + <varlistentry id="opt.lg_prof_sample"> + <term> + <mallctl>opt.lg_prof_sample</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>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).</para></listitem> + </varlistentry> + + <varlistentry id="opt.prof_accum"> + <term> + <mallctl>opt.prof_accum</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>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.</para></listitem> + </varlistentry> + + <varlistentry id="opt.lg_prof_interval"> + <term> + <mallctl>opt.lg_prof_interval</mallctl> + (<type>ssize_t</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>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 + <filename><prefix>.<pid>.<seq>.i<iseq>.heap</filename>, + where <literal><prefix></literal> is controlled by the + <link + linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> + option. By default, interval-triggered profile dumping is disabled + (encoded as -1). + </para></listitem> + </varlistentry> + + <varlistentry id="opt.prof_gdump"> + <term> + <mallctl>opt.prof_gdump</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Set the initial state of <link + linkend="prof.gdump"><mallctl>prof.gdump</mallctl></link>, which when + enabled triggers a memory profile dump every time the total virtual + memory exceeds the previous maximum. This option is disabled by + default.</para></listitem> + </varlistentry> + + <varlistentry id="opt.prof_final"> + <term> + <mallctl>opt.prof_final</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Use an + <citerefentry><refentrytitle>atexit</refentrytitle> + <manvolnum>3</manvolnum></citerefentry> function to dump final memory + usage to a file named according to the pattern + <filename><prefix>.<pid>.<seq>.f.heap</filename>, + where <literal><prefix></literal> is controlled by the <link + linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> + option. Note that <function>atexit()</function> may allocate + memory during application initialization and then deadlock internally + when jemalloc in turn calls <function>atexit()</function>, so + this option is not universally usable (though the application can + register its own <function>atexit()</function> function with + equivalent functionality). This option is disabled by + default.</para></listitem> + </varlistentry> + + <varlistentry id="opt.prof_leak"> + <term> + <mallctl>opt.prof_leak</mallctl> + (<type>bool</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Leak reporting enabled/disabled. If enabled, use an + <citerefentry><refentrytitle>atexit</refentrytitle> + <manvolnum>3</manvolnum></citerefentry> function to report memory leaks + detected by allocation sampling. See the + <link linkend="opt.prof"><mallctl>opt.prof</mallctl></link> option for + information on analyzing heap profile output. This option is disabled + by default.</para></listitem> + </varlistentry> + + <varlistentry id="thread.arena"> + <term> + <mallctl>thread.arena</mallctl> + (<type>unsigned</type>) + <literal>rw</literal> + </term> + <listitem><para>Get or set the arena associated with the calling + thread. If the specified arena was not initialized beforehand (see the + <link + linkend="arenas.initialized"><mallctl>arenas.initialized</mallctl></link> + mallctl), it will be automatically initialized as a side effect of + calling this interface.</para></listitem> + </varlistentry> + + <varlistentry id="thread.allocated"> + <term> + <mallctl>thread.allocated</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>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.</para></listitem> + </varlistentry> + + <varlistentry id="thread.allocatedp"> + <term> + <mallctl>thread.allocatedp</mallctl> + (<type>uint64_t *</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Get a pointer to the the value that is returned by the + <link + linkend="thread.allocated"><mallctl>thread.allocated</mallctl></link> + mallctl. This is useful for avoiding the overhead of repeated + <function>mallctl*()</function> calls.</para></listitem> + </varlistentry> + + <varlistentry id="thread.deallocated"> + <term> + <mallctl>thread.deallocated</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>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.</para></listitem> + </varlistentry> + + <varlistentry id="thread.deallocatedp"> + <term> + <mallctl>thread.deallocatedp</mallctl> + (<type>uint64_t *</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Get a pointer to the the value that is returned by the + <link + linkend="thread.deallocated"><mallctl>thread.deallocated</mallctl></link> + mallctl. This is useful for avoiding the overhead of repeated + <function>mallctl*()</function> calls.</para></listitem> + </varlistentry> + + <varlistentry id="thread.tcache.enabled"> + <term> + <mallctl>thread.tcache.enabled</mallctl> + (<type>bool</type>) + <literal>rw</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Enable/disable calling thread's tcache. The tcache is + implicitly flushed as a side effect of becoming + disabled (see <link + linkend="thread.tcache.flush"><mallctl>thread.tcache.flush</mallctl></link>). + </para></listitem> + </varlistentry> + + <varlistentry id="thread.tcache.flush"> + <term> + <mallctl>thread.tcache.flush</mallctl> + (<type>void</type>) + <literal>--</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Flush calling thread's thread-specific cache (tcache). + This interface releases all cached objects and internal data structures + associated with the calling thread's tcache. 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.</para></listitem> + </varlistentry> + + <varlistentry id="thread.prof.name"> + <term> + <mallctl>thread.prof.name</mallctl> + (<type>const char *</type>) + <literal>r-</literal> or + <literal>-w</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Get/set the descriptive name associated with the calling + thread in memory profile dumps. An internal copy of the name string is + created, so the input string need not be maintained after this interface + completes execution. The output string of this interface should be + copied for non-ephemeral uses, because multiple implementation details + can cause asynchronous string deallocation. Furthermore, each + invocation of this interface can only read or write; simultaneous + read/write is not supported due to string lifetime limitations. The + name string must be nil-terminated and comprised only of characters in + the sets recognized + by <citerefentry><refentrytitle>isgraph</refentrytitle> + <manvolnum>3</manvolnum></citerefentry> and + <citerefentry><refentrytitle>isblank</refentrytitle> + <manvolnum>3</manvolnum></citerefentry>.</para></listitem> + </varlistentry> + + <varlistentry id="thread.prof.active"> + <term> + <mallctl>thread.prof.active</mallctl> + (<type>bool</type>) + <literal>rw</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Control whether sampling is currently active for the + calling thread. This is an activation mechanism in addition to <link + linkend="prof.active"><mallctl>prof.active</mallctl></link>; both must + be active for the calling thread to sample. This flag is enabled by + default.</para></listitem> + </varlistentry> + + <varlistentry id="tcache.create"> + <term> + <mallctl>tcache.create</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Create an explicit thread-specific cache (tcache) and + return an identifier that can be passed to the <link + linkend="MALLOCX_TCACHE"><constant>MALLOCX_TCACHE(<parameter>tc</parameter>)</constant></link> + macro to explicitly use the specified cache rather than the + automatically managed one that is used by default. Each explicit cache + can be used by only one thread at a time; the application must assure + that this constraint holds. + </para></listitem> + </varlistentry> + + <varlistentry id="tcache.flush"> + <term> + <mallctl>tcache.flush</mallctl> + (<type>unsigned</type>) + <literal>-w</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Flush the specified thread-specific cache (tcache). The + same considerations apply to this interface as to <link + linkend="thread.tcache.flush"><mallctl>thread.tcache.flush</mallctl></link>, + except that the tcache will never be automatically discarded. + </para></listitem> + </varlistentry> + + <varlistentry id="tcache.destroy"> + <term> + <mallctl>tcache.destroy</mallctl> + (<type>unsigned</type>) + <literal>-w</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Flush the specified thread-specific cache (tcache) and + make the identifier available for use during a future tcache creation. + </para></listitem> + </varlistentry> + + <varlistentry id="arena.i.purge"> + <term> + <mallctl>arena.<i>.purge</mallctl> + (<type>void</type>) + <literal>--</literal> + </term> + <listitem><para>Purge all unused dirty pages for arena <i>, or for + all arenas if <i> equals <link + linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>. + </para></listitem> + </varlistentry> + + <varlistentry id="arena.i.decay"> + <term> + <mallctl>arena.<i>.decay</mallctl> + (<type>void</type>) + <literal>--</literal> + </term> + <listitem><para>Trigger decay-based purging of unused dirty pages for + arena <i>, or for all arenas if <i> equals <link + linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>. + The proportion of unused dirty pages to be purged depends on the current + time; see <link + linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for + details.</para></listitem> + </varlistentry> + + <varlistentry id="arena.i.reset"> + <term> + <mallctl>arena.<i>.reset</mallctl> + (<type>void</type>) + <literal>--</literal> + </term> + <listitem><para>Discard all of the arena's extant allocations. This + interface can only be used with arenas created via <link + linkend="arenas.extend"><mallctl>arenas.extend</mallctl></link>. None + of the arena's discarded/cached allocations may accessed afterward. As + part of this requirement, all thread caches which were used to + allocate/deallocate in conjunction with the arena must be flushed + beforehand. This interface cannot be used if running inside Valgrind, + nor if the <link linkend="opt.quarantine">quarantine</link> size is + non-zero.</para></listitem> + </varlistentry> + + <varlistentry id="arena.i.dss"> + <term> + <mallctl>arena.<i>.dss</mallctl> + (<type>const char *</type>) + <literal>rw</literal> + </term> + <listitem><para>Set the precedence of dss allocation as related to mmap + allocation for arena <i>, or for all arenas if <i> equals + <link + linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>. See + <link linkend="opt.dss"><mallctl>opt.dss</mallctl></link> for supported + settings.</para></listitem> + </varlistentry> + + <varlistentry id="arena.i.lg_dirty_mult"> + <term> + <mallctl>arena.<i>.lg_dirty_mult</mallctl> + (<type>ssize_t</type>) + <literal>rw</literal> + </term> + <listitem><para>Current per-arena minimum ratio (log base 2) of active + to dirty pages for arena <i>. Each time this interface is set and + the ratio is increased, pages are synchronously purged as necessary to + impose the new ratio. See <link + linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> + for additional information.</para></listitem> + </varlistentry> + + <varlistentry id="arena.i.decay_time"> + <term> + <mallctl>arena.<i>.decay_time</mallctl> + (<type>ssize_t</type>) + <literal>rw</literal> + </term> + <listitem><para>Current per-arena approximate time in seconds from the + creation of a set of unused dirty pages until an equivalent set of + unused dirty pages is purged and/or reused. Each time this interface is + set, all currently unused dirty pages are considered to have fully + decayed, which causes immediate purging of all unused dirty pages unless + the decay time is set to -1 (i.e. purging disabled). See <link + linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for + additional information.</para></listitem> + </varlistentry> + + <varlistentry id="arena.i.chunk_hooks"> + <term> + <mallctl>arena.<i>.chunk_hooks</mallctl> + (<type>chunk_hooks_t</type>) + <literal>rw</literal> + </term> + <listitem><para>Get or set the chunk management hook functions for arena + <i>. The functions must be capable of operating on all extant + chunks associated with arena <i>, usually by passing unknown + chunks to the replaced functions. In practice, it is feasible to + control allocation for arenas created via <link + linkend="arenas.extend"><mallctl>arenas.extend</mallctl></link> such + that all chunks originate from an application-supplied chunk allocator + (by setting custom chunk hook functions just after arena creation), but + the automatically created arenas may have already created chunks prior + to the application having an opportunity to take over chunk + allocation.</para> + + <programlisting language="C"><![CDATA[ +typedef struct { + chunk_alloc_t *alloc; + chunk_dalloc_t *dalloc; + chunk_commit_t *commit; + chunk_decommit_t *decommit; + chunk_purge_t *purge; + chunk_split_t *split; + chunk_merge_t *merge; +} chunk_hooks_t;]]></programlisting> + <para>The <type>chunk_hooks_t</type> structure comprises function + pointers which are described individually below. jemalloc uses these + functions to manage chunk lifetime, which starts off with allocation of + mapped committed memory, in the simplest case followed by deallocation. + However, there are performance and platform reasons to retain chunks for + later reuse. Cleanup attempts cascade from deallocation to decommit to + purging, which gives the chunk management functions opportunities to + reject the most permanent cleanup operations in favor of less permanent + (and often less costly) operations. The chunk splitting and merging + operations can also be opted out of, but this is mainly intended to + support platforms on which virtual memory mappings provided by the + operating system kernel do not automatically coalesce and split, e.g. + Windows.</para> + + <funcsynopsis><funcprototype> + <funcdef>typedef void *<function>(chunk_alloc_t)</function></funcdef> + <paramdef>void *<parameter>chunk</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>size_t <parameter>alignment</parameter></paramdef> + <paramdef>bool *<parameter>zero</parameter></paramdef> + <paramdef>bool *<parameter>commit</parameter></paramdef> + <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> + </funcprototype></funcsynopsis> + <literallayout></literallayout> + <para>A chunk allocation function conforms to the + <type>chunk_alloc_t</type> type and upon success returns a pointer to + <parameter>size</parameter> bytes of mapped memory on behalf of arena + <parameter>arena_ind</parameter> such that the chunk's base address is a + multiple of <parameter>alignment</parameter>, as well as setting + <parameter>*zero</parameter> to indicate whether the chunk is zeroed and + <parameter>*commit</parameter> to indicate whether the chunk is + committed. Upon error the function returns <constant>NULL</constant> + and leaves <parameter>*zero</parameter> and + <parameter>*commit</parameter> unmodified. The + <parameter>size</parameter> parameter is always a multiple of the chunk + size. The <parameter>alignment</parameter> parameter is always a power + of two at least as large as the chunk size. Zeroing is mandatory if + <parameter>*zero</parameter> is true upon function entry. Committing is + mandatory if <parameter>*commit</parameter> is true upon function entry. + If <parameter>chunk</parameter> is not <constant>NULL</constant>, the + returned pointer must be <parameter>chunk</parameter> on success or + <constant>NULL</constant> on error. Committed memory may be committed + in absolute terms as on a system that does not overcommit, or in + implicit terms as on a system that overcommits and satisfies physical + memory needs on demand via soft page faults. Note that replacing the + default chunk allocation function makes the arena's <link + linkend="arena.i.dss"><mallctl>arena.<i>.dss</mallctl></link> + setting irrelevant.</para> + + <funcsynopsis><funcprototype> + <funcdef>typedef bool <function>(chunk_dalloc_t)</function></funcdef> + <paramdef>void *<parameter>chunk</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>bool <parameter>committed</parameter></paramdef> + <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> + </funcprototype></funcsynopsis> + <literallayout></literallayout> + <para> + A chunk deallocation function conforms to the + <type>chunk_dalloc_t</type> type and deallocates a + <parameter>chunk</parameter> of given <parameter>size</parameter> with + <parameter>committed</parameter>/decommited memory as indicated, on + behalf of arena <parameter>arena_ind</parameter>, returning false upon + success. If the function returns true, this indicates opt-out from + deallocation; the virtual memory mapping associated with the chunk + remains mapped, in the same commit state, and available for future use, + in which case it will be automatically retained for later reuse.</para> + + <funcsynopsis><funcprototype> + <funcdef>typedef bool <function>(chunk_commit_t)</function></funcdef> + <paramdef>void *<parameter>chunk</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>size_t <parameter>offset</parameter></paramdef> + <paramdef>size_t <parameter>length</parameter></paramdef> + <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> + </funcprototype></funcsynopsis> + <literallayout></literallayout> + <para>A chunk commit function conforms to the + <type>chunk_commit_t</type> type and commits zeroed physical memory to + back pages within a <parameter>chunk</parameter> of given + <parameter>size</parameter> at <parameter>offset</parameter> bytes, + extending for <parameter>length</parameter> on behalf of arena + <parameter>arena_ind</parameter>, returning false upon success. + Committed memory may be committed in absolute terms as on a system that + does not overcommit, or in implicit terms as on a system that + overcommits and satisfies physical memory needs on demand via soft page + faults. If the function returns true, this indicates insufficient + physical memory to satisfy the request.</para> + + <funcsynopsis><funcprototype> + <funcdef>typedef bool <function>(chunk_decommit_t)</function></funcdef> + <paramdef>void *<parameter>chunk</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>size_t <parameter>offset</parameter></paramdef> + <paramdef>size_t <parameter>length</parameter></paramdef> + <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> + </funcprototype></funcsynopsis> + <literallayout></literallayout> + <para>A chunk decommit function conforms to the + <type>chunk_decommit_t</type> type and decommits any physical memory + that is backing pages within a <parameter>chunk</parameter> of given + <parameter>size</parameter> at <parameter>offset</parameter> bytes, + extending for <parameter>length</parameter> on behalf of arena + <parameter>arena_ind</parameter>, returning false upon success, in which + case the pages will be committed via the chunk commit function before + being reused. If the function returns true, this indicates opt-out from + decommit; the memory remains committed and available for future use, in + which case it will be automatically retained for later reuse.</para> + + <funcsynopsis><funcprototype> + <funcdef>typedef bool <function>(chunk_purge_t)</function></funcdef> + <paramdef>void *<parameter>chunk</parameter></paramdef> + <paramdef>size_t<parameter>size</parameter></paramdef> + <paramdef>size_t <parameter>offset</parameter></paramdef> + <paramdef>size_t <parameter>length</parameter></paramdef> + <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> + </funcprototype></funcsynopsis> + <literallayout></literallayout> + <para>A chunk purge function conforms to the <type>chunk_purge_t</type> + type and optionally discards physical pages within the virtual memory + mapping associated with <parameter>chunk</parameter> of given + <parameter>size</parameter> at <parameter>offset</parameter> bytes, + extending for <parameter>length</parameter> on behalf of arena + <parameter>arena_ind</parameter>, returning false if pages within the + purged virtual memory range will be zero-filled the next time they are + accessed.</para> + + <funcsynopsis><funcprototype> + <funcdef>typedef bool <function>(chunk_split_t)</function></funcdef> + <paramdef>void *<parameter>chunk</parameter></paramdef> + <paramdef>size_t <parameter>size</parameter></paramdef> + <paramdef>size_t <parameter>size_a</parameter></paramdef> + <paramdef>size_t <parameter>size_b</parameter></paramdef> + <paramdef>bool <parameter>committed</parameter></paramdef> + <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> + </funcprototype></funcsynopsis> + <literallayout></literallayout> + <para>A chunk split function conforms to the <type>chunk_split_t</type> + type and optionally splits <parameter>chunk</parameter> of given + <parameter>size</parameter> into two adjacent chunks, the first of + <parameter>size_a</parameter> bytes, and the second of + <parameter>size_b</parameter> bytes, operating on + <parameter>committed</parameter>/decommitted memory as indicated, on + behalf of arena <parameter>arena_ind</parameter>, returning false upon + success. If the function returns true, this indicates that the chunk + remains unsplit and therefore should continue to be operated on as a + whole.</para> + + <funcsynopsis><funcprototype> + <funcdef>typedef bool <function>(chunk_merge_t)</function></funcdef> + <paramdef>void *<parameter>chunk_a</parameter></paramdef> + <paramdef>size_t <parameter>size_a</parameter></paramdef> + <paramdef>void *<parameter>chunk_b</parameter></paramdef> + <paramdef>size_t <parameter>size_b</parameter></paramdef> + <paramdef>bool <parameter>committed</parameter></paramdef> + <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> + </funcprototype></funcsynopsis> + <literallayout></literallayout> + <para>A chunk merge function conforms to the <type>chunk_merge_t</type> + type and optionally merges adjacent chunks, + <parameter>chunk_a</parameter> of given <parameter>size_a</parameter> + and <parameter>chunk_b</parameter> of given + <parameter>size_b</parameter> into one contiguous chunk, operating on + <parameter>committed</parameter>/decommitted memory as indicated, on + behalf of arena <parameter>arena_ind</parameter>, returning false upon + success. If the function returns true, this indicates that the chunks + remain distinct mappings and therefore should continue to be operated on + independently.</para> + </listitem> + </varlistentry> + + <varlistentry id="arenas.narenas"> + <term> + <mallctl>arenas.narenas</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + </term> + <listitem><para>Current limit on number of arenas.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.initialized"> + <term> + <mallctl>arenas.initialized</mallctl> + (<type>bool *</type>) + <literal>r-</literal> + </term> + <listitem><para>An array of <link + linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link> + booleans. Each boolean indicates whether the corresponding arena is + initialized.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.lg_dirty_mult"> + <term> + <mallctl>arenas.lg_dirty_mult</mallctl> + (<type>ssize_t</type>) + <literal>rw</literal> + </term> + <listitem><para>Current default per-arena minimum ratio (log base 2) of + active to dirty pages, used to initialize <link + linkend="arena.i.lg_dirty_mult"><mallctl>arena.<i>.lg_dirty_mult</mallctl></link> + during arena creation. See <link + linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> + for additional information.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.decay_time"> + <term> + <mallctl>arenas.decay_time</mallctl> + (<type>ssize_t</type>) + <literal>rw</literal> + </term> + <listitem><para>Current default per-arena approximate time in seconds + from the creation of a set of unused dirty pages until an equivalent set + of unused dirty pages is purged and/or reused, used to initialize <link + linkend="arena.i.decay_time"><mallctl>arena.<i>.decay_time</mallctl></link> + during arena creation. See <link + linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for + additional information.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.quantum"> + <term> + <mallctl>arenas.quantum</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Quantum size.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.page"> + <term> + <mallctl>arenas.page</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Page size.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.tcache_max"> + <term> + <mallctl>arenas.tcache_max</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Maximum thread-cached size class.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.nbins"> + <term> + <mallctl>arenas.nbins</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + </term> + <listitem><para>Number of bin size classes.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.nhbins"> + <term> + <mallctl>arenas.nhbins</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + [<option>--enable-tcache</option>] + </term> + <listitem><para>Total number of thread cache bin size + classes.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.bin.i.size"> + <term> + <mallctl>arenas.bin.<i>.size</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Maximum size supported by size class.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.bin.i.nregs"> + <term> + <mallctl>arenas.bin.<i>.nregs</mallctl> + (<type>uint32_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Number of regions per page run.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.bin.i.run_size"> + <term> + <mallctl>arenas.bin.<i>.run_size</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Number of bytes per page run.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.nlruns"> + <term> + <mallctl>arenas.nlruns</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + </term> + <listitem><para>Total number of large size classes.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.lrun.i.size"> + <term> + <mallctl>arenas.lrun.<i>.size</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Maximum size supported by this large size + class.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.nhchunks"> + <term> + <mallctl>arenas.nhchunks</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + </term> + <listitem><para>Total number of huge size classes.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.hchunk.i.size"> + <term> + <mallctl>arenas.hchunk.<i>.size</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Maximum size supported by this huge size + class.</para></listitem> + </varlistentry> + + <varlistentry id="arenas.extend"> + <term> + <mallctl>arenas.extend</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + </term> + <listitem><para>Extend the array of arenas by appending a new arena, + and returning the new arena index.</para></listitem> + </varlistentry> + + <varlistentry id="prof.thread_active_init"> + <term> + <mallctl>prof.thread_active_init</mallctl> + (<type>bool</type>) + <literal>rw</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Control the initial setting for <link + linkend="thread.prof.active"><mallctl>thread.prof.active</mallctl></link> + in newly created threads. See the <link + linkend="opt.prof_thread_active_init"><mallctl>opt.prof_thread_active_init</mallctl></link> + option for additional information.</para></listitem> + </varlistentry> + + <varlistentry id="prof.active"> + <term> + <mallctl>prof.active</mallctl> + (<type>bool</type>) + <literal>rw</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Control whether sampling is currently active. See the + <link + linkend="opt.prof_active"><mallctl>opt.prof_active</mallctl></link> + option for additional information, as well as the interrelated <link + linkend="thread.prof.active"><mallctl>thread.prof.active</mallctl></link> + mallctl.</para></listitem> + </varlistentry> + + <varlistentry id="prof.dump"> + <term> + <mallctl>prof.dump</mallctl> + (<type>const char *</type>) + <literal>-w</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Dump a memory profile to the specified file, or if NULL + is specified, to a file according to the pattern + <filename><prefix>.<pid>.<seq>.m<mseq>.heap</filename>, + where <literal><prefix></literal> is controlled by the + <link + linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> + option.</para></listitem> + </varlistentry> + + <varlistentry id="prof.gdump"> + <term> + <mallctl>prof.gdump</mallctl> + (<type>bool</type>) + <literal>rw</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>When enabled, 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 + <filename><prefix>.<pid>.<seq>.u<useq>.heap</filename>, + where <literal><prefix></literal> is controlled by the <link + linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> + option.</para></listitem> + </varlistentry> + + <varlistentry id="prof.reset"> + <term> + <mallctl>prof.reset</mallctl> + (<type>size_t</type>) + <literal>-w</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Reset all memory profile statistics, and optionally + update the sample rate (see <link + linkend="opt.lg_prof_sample"><mallctl>opt.lg_prof_sample</mallctl></link> + and <link + linkend="prof.lg_sample"><mallctl>prof.lg_sample</mallctl></link>). + </para></listitem> + </varlistentry> + + <varlistentry id="prof.lg_sample"> + <term> + <mallctl>prof.lg_sample</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Get the current sample rate (see <link + linkend="opt.lg_prof_sample"><mallctl>opt.lg_prof_sample</mallctl></link>). + </para></listitem> + </varlistentry> + + <varlistentry id="prof.interval"> + <term> + <mallctl>prof.interval</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-prof</option>] + </term> + <listitem><para>Average number of bytes allocated between + interval-based profile dumps. See the + <link + linkend="opt.lg_prof_interval"><mallctl>opt.lg_prof_interval</mallctl></link> + option for additional information.</para></listitem> + </varlistentry> + + <varlistentry id="stats.cactive"> + <term> + <mallctl>stats.cactive</mallctl> + (<type>size_t *</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>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 when computing its + contribution to the counter. Note that the <link + linkend="epoch"><mallctl>epoch</mallctl></link> 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. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.allocated"> + <term> + <mallctl>stats.allocated</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Total number of bytes allocated by the + application.</para></listitem> + </varlistentry> + + <varlistentry id="stats.active"> + <term> + <mallctl>stats.active</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>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 <link + linkend="stats.allocated"><mallctl>stats.allocated</mallctl></link>. + This does not include <link linkend="stats.arenas.i.pdirty"> + <mallctl>stats.arenas.<i>.pdirty</mallctl></link>, nor pages + entirely devoted to allocator metadata.</para></listitem> + </varlistentry> + + <varlistentry id="stats.metadata"> + <term> + <mallctl>stats.metadata</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Total number of bytes dedicated to metadata, which + comprise base allocations used for bootstrap-sensitive internal + allocator data structures, arena chunk headers (see <link + linkend="stats.arenas.i.metadata.mapped"><mallctl>stats.arenas.<i>.metadata.mapped</mallctl></link>), + and internal allocations (see <link + linkend="stats.arenas.i.metadata.allocated"><mallctl>stats.arenas.<i>.metadata.allocated</mallctl></link>).</para></listitem> + </varlistentry> + + <varlistentry id="stats.resident"> + <term> + <mallctl>stats.resident</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Maximum number of bytes in physically resident data + pages mapped by the allocator, comprising all pages dedicated to + allocator metadata, pages backing active allocations, and unused dirty + pages. This is a maximum rather than precise because pages may not + actually be physically resident if they correspond to demand-zeroed + virtual memory that has not yet been touched. This is a multiple of the + page size, and is larger than <link + linkend="stats.active"><mallctl>stats.active</mallctl></link>.</para></listitem> + </varlistentry> + + <varlistentry id="stats.mapped"> + <term> + <mallctl>stats.mapped</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Total number of bytes in active chunks mapped by the + allocator. This is a multiple of the chunk size, and is larger than + <link linkend="stats.active"><mallctl>stats.active</mallctl></link>. + This does not include inactive chunks, even those that contain unused + dirty pages, which means that there is no strict ordering between this + and <link + linkend="stats.resident"><mallctl>stats.resident</mallctl></link>.</para></listitem> + </varlistentry> + + <varlistentry id="stats.retained"> + <term> + <mallctl>stats.retained</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Total number of bytes in virtual memory mappings that + were retained rather than being returned to the operating system via + e.g. <citerefentry><refentrytitle>munmap</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>. Retained virtual memory is + typically untouched, decommitted, or purged, so it has no strongly + associated physical memory (see <link + linkend="arena.i.chunk_hooks">chunk hooks</link> for details). Retained + memory is excluded from mapped memory statistics, e.g. <link + linkend="stats.mapped"><mallctl>stats.mapped</mallctl></link>. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.dss"> + <term> + <mallctl>stats.arenas.<i>.dss</mallctl> + (<type>const char *</type>) + <literal>r-</literal> + </term> + <listitem><para>dss (<citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>) allocation precedence as + related to <citerefentry><refentrytitle>mmap</refentrytitle> + <manvolnum>2</manvolnum></citerefentry> allocation. See <link + linkend="opt.dss"><mallctl>opt.dss</mallctl></link> for details. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.lg_dirty_mult"> + <term> + <mallctl>stats.arenas.<i>.lg_dirty_mult</mallctl> + (<type>ssize_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Minimum ratio (log base 2) of active to dirty pages. + See <link + linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> + for details.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.decay_time"> + <term> + <mallctl>stats.arenas.<i>.decay_time</mallctl> + (<type>ssize_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Approximate time in seconds from the creation of a set + of unused dirty pages until an equivalent set of unused dirty pages is + purged and/or reused. See <link + linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> + for details.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.nthreads"> + <term> + <mallctl>stats.arenas.<i>.nthreads</mallctl> + (<type>unsigned</type>) + <literal>r-</literal> + </term> + <listitem><para>Number of threads currently assigned to + arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.pactive"> + <term> + <mallctl>stats.arenas.<i>.pactive</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Number of pages in active runs.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.pdirty"> + <term> + <mallctl>stats.arenas.<i>.pdirty</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + </term> + <listitem><para>Number of pages within unused runs that are potentially + dirty, and for which <function>madvise<parameter>...</parameter> + <parameter><constant>MADV_DONTNEED</constant></parameter></function> or + similar has not been called.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.mapped"> + <term> + <mallctl>stats.arenas.<i>.mapped</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of mapped bytes.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.retained"> + <term> + <mallctl>stats.arenas.<i>.retained</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of retained bytes. See <link + linkend="stats.retained"><mallctl>stats.retained</mallctl></link> for + details.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.metadata.mapped"> + <term> + <mallctl>stats.arenas.<i>.metadata.mapped</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of mapped bytes in arena chunk headers, which + track the states of the non-metadata pages.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.metadata.allocated"> + <term> + <mallctl>stats.arenas.<i>.metadata.allocated</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of bytes dedicated to internal allocations. + Internal allocations differ from application-originated allocations in + that they are for internal use, and that they are omitted from heap + profiles. This statistic is reported separately from <link + linkend="stats.metadata"><mallctl>stats.metadata</mallctl></link> and + <link + linkend="stats.arenas.i.metadata.mapped"><mallctl>stats.arenas.<i>.metadata.mapped</mallctl></link> + because it overlaps with e.g. the <link + linkend="stats.allocated"><mallctl>stats.allocated</mallctl></link> and + <link linkend="stats.active"><mallctl>stats.active</mallctl></link> + statistics, whereas the other metadata statistics do + not.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.npurge"> + <term> + <mallctl>stats.arenas.<i>.npurge</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of dirty page purge sweeps performed. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.nmadvise"> + <term> + <mallctl>stats.arenas.<i>.nmadvise</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of <function>madvise<parameter>...</parameter> + <parameter><constant>MADV_DONTNEED</constant></parameter></function> or + similar calls made to purge dirty pages.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.purged"> + <term> + <mallctl>stats.arenas.<i>.purged</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of pages purged.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.small.allocated"> + <term> + <mallctl>stats.arenas.<i>.small.allocated</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of bytes currently allocated by small objects. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.small.nmalloc"> + <term> + <mallctl>stats.arenas.<i>.small.nmalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocation requests served by + small bins.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.small.ndalloc"> + <term> + <mallctl>stats.arenas.<i>.small.ndalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of small objects returned to bins. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.small.nrequests"> + <term> + <mallctl>stats.arenas.<i>.small.nrequests</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of small allocation requests. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.large.allocated"> + <term> + <mallctl>stats.arenas.<i>.large.allocated</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of bytes currently allocated by large objects. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.large.nmalloc"> + <term> + <mallctl>stats.arenas.<i>.large.nmalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of large allocation requests served + directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.large.ndalloc"> + <term> + <mallctl>stats.arenas.<i>.large.ndalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of large deallocation requests served + directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.large.nrequests"> + <term> + <mallctl>stats.arenas.<i>.large.nrequests</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of large allocation requests. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.huge.allocated"> + <term> + <mallctl>stats.arenas.<i>.huge.allocated</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Number of bytes currently allocated by huge objects. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.huge.nmalloc"> + <term> + <mallctl>stats.arenas.<i>.huge.nmalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of huge allocation requests served + directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.huge.ndalloc"> + <term> + <mallctl>stats.arenas.<i>.huge.ndalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of huge deallocation requests served + directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.huge.nrequests"> + <term> + <mallctl>stats.arenas.<i>.huge.nrequests</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of huge allocation requests. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.nmalloc"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.nmalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocations served by bin. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.ndalloc"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.ndalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocations returned to bin. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.nrequests"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.nrequests</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocation + requests.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.curregs"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.curregs</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Current number of regions for this size + class.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.nfills"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.nfills</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option> <option>--enable-tcache</option>] + </term> + <listitem><para>Cumulative number of tcache fills.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.nflushes"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.nflushes</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option> <option>--enable-tcache</option>] + </term> + <listitem><para>Cumulative number of tcache flushes.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.nruns"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.nruns</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of runs created.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.nreruns"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.nreruns</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of times the current run from which + to allocate changed.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.bins.j.curruns"> + <term> + <mallctl>stats.arenas.<i>.bins.<j>.curruns</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Current number of runs.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.lruns.j.nmalloc"> + <term> + <mallctl>stats.arenas.<i>.lruns.<j>.nmalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocation requests for this size + class served directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.lruns.j.ndalloc"> + <term> + <mallctl>stats.arenas.<i>.lruns.<j>.ndalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of deallocation requests for this + size class served directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.lruns.j.nrequests"> + <term> + <mallctl>stats.arenas.<i>.lruns.<j>.nrequests</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocation requests for this size + class.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.lruns.j.curruns"> + <term> + <mallctl>stats.arenas.<i>.lruns.<j>.curruns</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Current number of runs for this size class. + </para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.hchunks.j.nmalloc"> + <term> + <mallctl>stats.arenas.<i>.hchunks.<j>.nmalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocation requests for this size + class served directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.hchunks.j.ndalloc"> + <term> + <mallctl>stats.arenas.<i>.hchunks.<j>.ndalloc</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of deallocation requests for this + size class served directly by the arena.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.hchunks.j.nrequests"> + <term> + <mallctl>stats.arenas.<i>.hchunks.<j>.nrequests</mallctl> + (<type>uint64_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Cumulative number of allocation requests for this size + class.</para></listitem> + </varlistentry> + + <varlistentry id="stats.arenas.i.hchunks.j.curhchunks"> + <term> + <mallctl>stats.arenas.<i>.hchunks.<j>.curhchunks</mallctl> + (<type>size_t</type>) + <literal>r-</literal> + [<option>--enable-stats</option>] + </term> + <listitem><para>Current number of huge allocations for this size class. + </para></listitem> + </varlistentry> + </variablelist> + </refsect1> + <refsect1 id="heap_profile_format"> + <title>HEAP PROFILE FORMAT</title> + <para>Although the heap profiling functionality was originally designed to + be compatible with the + <command>pprof</command> command that is developed as part of the <ulink + url="http://code.google.com/p/gperftools/">gperftools + package</ulink>, the addition of per thread heap profiling functionality + required a different heap profile format. The <command>jeprof</command> + command is derived from <command>pprof</command>, with enhancements to + support the heap profile format described here.</para> + + <para>In the following hypothetical heap profile, <constant>[...]</constant> + indicates elision for the sake of compactness. <programlisting><![CDATA[ +heap_v2/524288 + t*: 28106: 56637512 [0: 0] + [...] + t3: 352: 16777344 [0: 0] + [...] + t99: 17754: 29341640 [0: 0] + [...] +@ 0x5f86da8 0x5f5a1dc [...] 0x29e4d4e 0xa200316 0xabb2988 [...] + t*: 13: 6688 [0: 0] + t3: 12: 6496 [0: ] + t99: 1: 192 [0: 0] +[...] + +MAPPED_LIBRARIES: +[...]]]></programlisting> The following matches the above heap profile, but most +tokens are replaced with <constant><description></constant> to indicate +descriptions of the corresponding fields. <programlisting><![CDATA[ +<heap_profile_format_version>/<mean_sample_interval> + <aggregate>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] + [...] + <thread_3_aggregate>: <curobjs>: <curbytes>[<cumobjs>: <cumbytes>] + [...] + <thread_99_aggregate>: <curobjs>: <curbytes>[<cumobjs>: <cumbytes>] + [...] +@ <top_frame> <frame> [...] <frame> <frame> <frame> [...] + <backtrace_aggregate>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] + <backtrace_thread_3>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] + <backtrace_thread_99>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] +[...] + +MAPPED_LIBRARIES: +</proc/<pid>/maps>]]></programlisting></para> + </refsect1> + + <refsect1 id="debugging_malloc_problems"> + <title>DEBUGGING MALLOC PROBLEMS</title> + <para>When debugging, it is a good idea to configure/build jemalloc with + the <option>--enable-debug</option> and <option>--enable-fill</option> + 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.</para> + + <para>Programs often accidentally depend on <quote>uninitialized</quote> + memory actually being filled with zero bytes. Junk filling + (see the <link linkend="opt.junk"><mallctl>opt.junk</mallctl></link> + option) tends to expose such bugs in the form of obviously incorrect + results and/or coredumps. Conversely, zero + filling (see the <link + linkend="opt.zero"><mallctl>opt.zero</mallctl></link> option) eliminates + the symptoms of such bugs. Between these two options, it is usually + possible to quickly detect, diagnose, and eliminate such bugs.</para> + + <para>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 <ulink url="http://valgrind.org/">Valgrind</ulink> tool if the + <option>--enable-valgrind</option> configuration option is enabled.</para> + </refsect1> + <refsect1 id="diagnostic_messages"> + <title>DIAGNOSTIC MESSAGES</title> + <para>If any of the memory allocation/deallocation functions detect an + error or warning condition, a message will be printed to file descriptor + <constant>STDERR_FILENO</constant>. Errors will result in the process + dumping core. If the <link + linkend="opt.abort"><mallctl>opt.abort</mallctl></link> option is set, most + warnings are treated as errors.</para> + + <para>The <varname>malloc_message</varname> variable allows the programmer + to override the function which emits the text strings forming the errors + and warnings if for some reason the <constant>STDERR_FILENO</constant> file + descriptor is not suitable for this. + <function>malloc_message()</function> takes the + <parameter>cbopaque</parameter> pointer argument that is + <constant>NULL</constant> unless overridden by the arguments in a call to + <function>malloc_stats_print()</function>, 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.</para> + + <para>All messages are prefixed by + <quote><computeroutput><jemalloc>: </computeroutput></quote>.</para> + </refsect1> + <refsect1 id="return_values"> + <title>RETURN VALUES</title> + <refsect2> + <title>Standard API</title> + <para>The <function>malloc()</function> and + <function>calloc()</function> functions return a pointer to the + allocated memory if successful; otherwise a <constant>NULL</constant> + pointer is returned and <varname>errno</varname> is set to + <errorname>ENOMEM</errorname>.</para> + + <para>The <function>posix_memalign()</function> function + returns the value 0 if successful; otherwise it returns an error value. + The <function>posix_memalign()</function> function will fail + if: + <variablelist> + <varlistentry> + <term><errorname>EINVAL</errorname></term> + + <listitem><para>The <parameter>alignment</parameter> parameter is + not a power of 2 at least as large as + <code language="C">sizeof(<type>void *</type>)</code>. + </para></listitem> + </varlistentry> + <varlistentry> + <term><errorname>ENOMEM</errorname></term> + + <listitem><para>Memory allocation error.</para></listitem> + </varlistentry> + </variablelist> + </para> + + <para>The <function>aligned_alloc()</function> function returns + a pointer to the allocated memory if successful; otherwise a + <constant>NULL</constant> pointer is returned and + <varname>errno</varname> is set. The + <function>aligned_alloc()</function> function will fail if: + <variablelist> + <varlistentry> + <term><errorname>EINVAL</errorname></term> + + <listitem><para>The <parameter>alignment</parameter> parameter is + not a power of 2. + </para></listitem> + </varlistentry> + <varlistentry> + <term><errorname>ENOMEM</errorname></term> + + <listitem><para>Memory allocation error.</para></listitem> + </varlistentry> + </variablelist> + </para> + + <para>The <function>realloc()</function> function returns a + pointer, possibly identical to <parameter>ptr</parameter>, to the + allocated memory if successful; otherwise a <constant>NULL</constant> + pointer is returned, and <varname>errno</varname> is set to + <errorname>ENOMEM</errorname> if the error was the result of an + allocation failure. The <function>realloc()</function> + function always leaves the original buffer intact when an error occurs. + </para> + + <para>The <function>free()</function> function returns no + value.</para> + </refsect2> + <refsect2> + <title>Non-standard API</title> + <para>The <function>mallocx()</function> and + <function>rallocx()</function> functions return a pointer to + the allocated memory if successful; otherwise a <constant>NULL</constant> + pointer is returned to indicate insufficient contiguous memory was + available to service the allocation request. </para> + + <para>The <function>xallocx()</function> function returns the + real size of the resulting resized allocation pointed to by + <parameter>ptr</parameter>, which is a value less than + <parameter>size</parameter> if the allocation could not be adequately + grown in place. </para> + + <para>The <function>sallocx()</function> function returns the + real size of the allocation pointed to by <parameter>ptr</parameter>. + </para> + + <para>The <function>nallocx()</function> returns the real size + that would result from a successful equivalent + <function>mallocx()</function> function call, or zero if + insufficient memory is available to perform the size computation. </para> + + <para>The <function>mallctl()</function>, + <function>mallctlnametomib()</function>, and + <function>mallctlbymib()</function> functions return 0 on + success; otherwise they return an error value. The functions will fail + if: + <variablelist> + <varlistentry> + <term><errorname>EINVAL</errorname></term> + + <listitem><para><parameter>newp</parameter> is not + <constant>NULL</constant>, and <parameter>newlen</parameter> is too + large or too small. Alternatively, <parameter>*oldlenp</parameter> + is too large or too small; in this case as much data as possible + are read despite the error.</para></listitem> + </varlistentry> + <varlistentry> + <term><errorname>ENOENT</errorname></term> + + <listitem><para><parameter>name</parameter> or + <parameter>mib</parameter> specifies an unknown/invalid + value.</para></listitem> + </varlistentry> + <varlistentry> + <term><errorname>EPERM</errorname></term> + + <listitem><para>Attempt to read or write void value, or attempt to + write read-only value.</para></listitem> + </varlistentry> + <varlistentry> + <term><errorname>EAGAIN</errorname></term> + + <listitem><para>A memory allocation failure + occurred.</para></listitem> + </varlistentry> + <varlistentry> + <term><errorname>EFAULT</errorname></term> + + <listitem><para>An interface with side effects failed in some way + not directly related to <function>mallctl*()</function> + read/write processing.</para></listitem> + </varlistentry> + </variablelist> + </para> + + <para>The <function>malloc_usable_size()</function> function + returns the usable size of the allocation pointed to by + <parameter>ptr</parameter>. </para> + </refsect2> + </refsect1> + <refsect1 id="environment"> + <title>ENVIRONMENT</title> + <para>The following environment variable affects the execution of the + allocation functions: + <variablelist> + <varlistentry> + <term><envar>MALLOC_CONF</envar></term> + + <listitem><para>If the environment variable + <envar>MALLOC_CONF</envar> is set, the characters it contains + will be interpreted as options.</para></listitem> + </varlistentry> + </variablelist> + </para> + </refsect1> + <refsect1 id="examples"> + <title>EXAMPLES</title> + <para>To dump core whenever a problem occurs: + <screen>ln -s 'abort:true' /etc/malloc.conf</screen> + </para> + <para>To specify in the source a chunk size that is 16 MiB: + <programlisting language="C"><![CDATA[ +malloc_conf = "lg_chunk:24";]]></programlisting></para> + </refsect1> + <refsect1 id="see_also"> + <title>SEE ALSO</title> + <para><citerefentry><refentrytitle>madvise</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>, + <citerefentry><refentrytitle>mmap</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>, + <citerefentry><refentrytitle>sbrk</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>, + <citerefentry><refentrytitle>utrace</refentrytitle> + <manvolnum>2</manvolnum></citerefentry>, + <citerefentry><refentrytitle>alloca</refentrytitle> + <manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>atexit</refentrytitle> + <manvolnum>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>getpagesize</refentrytitle> + <manvolnum>3</manvolnum></citerefentry></para> + </refsect1> + <refsect1 id="standards"> + <title>STANDARDS</title> + <para>The <function>malloc()</function>, + <function>calloc()</function>, + <function>realloc()</function>, and + <function>free()</function> functions conform to ISO/IEC + 9899:1990 (<quote>ISO C90</quote>).</para> + + <para>The <function>posix_memalign()</function> function conforms + to IEEE Std 1003.1-2001 (<quote>POSIX.1</quote>).</para> + </refsect1> +</refentry> |