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| <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://www.canonware.com/jemalloc/">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<parameter/></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<parameter/></function> function allocates |
| space for <parameter>number</parameter> objects, each |
| <parameter>size</parameter> bytes in length. The result is identical to |
| calling <function>malloc<parameter/></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<parameter/></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<parameter/></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<parameter/></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<parameter/></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<parameter/></function> function behaves identically to |
| <function>malloc<parameter/></function> for the specified size.</para> |
| |
| <para>The <function>free<parameter/></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<parameter/></function>, |
| <function>rallocx<parameter/></function>, |
| <function>xallocx<parameter/></function>, |
| <function>sallocx<parameter/></function>, |
| <function>dallocx<parameter/></function>, |
| <function>sdallocx<parameter/></function>, and |
| <function>nallocx<parameter/></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> |
| <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> |
| <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> |
| <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> |
| <term><constant>MALLOCX_ARENA(<parameter>a</parameter>) |
| </constant></term> |
| |
| <listitem><para>Use the arena specified by the index |
| <parameter>a</parameter> (and by necessity bypass the thread |
| cache). 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<parameter/></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>, or if request size |
| overflows due to size class and/or alignment constraints.</para> |
| |
| <para>The <function>rallocx<parameter/></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>, or if request size |
| overflows due to size class and/or alignment constraints.</para> |
| |
| <para>The <function>xallocx<parameter/></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<parameter/></function> function returns the |
| real size of the allocation at <parameter>ptr</parameter>.</para> |
| |
| <para>The <function>dallocx<parameter/></function> function causes the |
| memory referenced by <parameter>ptr</parameter> to be made available for |
| future allocations.</para> |
| |
| <para>The <function>sdallocx<parameter/></function> function is an |
| extension of <function>dallocx<parameter/></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<parameter/></function> or |
| <function>sallocx<parameter/></function>.</para> |
| |
| <para>The <function>nallocx<parameter/></function> function allocates no |
| memory, but it performs the same size computation as the |
| <function>mallocx<parameter/></function> function, and returns the real |
| size of the allocation that would result from the equivalent |
| <function>mallocx<parameter/></function> function call. Behavior is |
| undefined if <parameter>size</parameter> is <constant>0</constant>, or if |
| request size overflows due to size class and/or alignment |
| constraints.</para> |
| |
| <para>The <function>mallctl<parameter/></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<parameter/></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 “Management Information Base” (MIB) that can be passed |
| repeatedly to <function>mallctlbymib<parameter/></function>. Upon |
| successful return from <function>mallctlnametomib<parameter/></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<parameter/></function> function |
| writes human-readable 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<parameter/></function> if |
| <parameter>write_cb</parameter> is <constant>NULL</constant>. This |
| function can be called repeatedly. General information that never |
| changes during execution can be omitted by specifying "g" as a character |
| within the <parameter>opts</parameter> string. Note that |
| <function>malloc_message<parameter/></function> uses the |
| <function>mallctl*<parameter/></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, “m” and “a” can |
| be specified to omit merged arena and per arena statistics, respectively; |
| “b”, “l”, and “h” 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<parameter/></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<parameter/></function> function is not a |
| mechanism for in-place <function>realloc<parameter/></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<parameter/></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 pointed to by the global variable |
| <varname>malloc_conf</varname>, the “name” 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<parameter/></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. <varname>malloc_conf</varname> is |
| a compile-time setting, 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.</para> |
| |
| <para>User objects are broken into three categories according to size: |
| small, large, and huge. Small and large objects are managed entirely by |
| arenas; huge objects are additionally aggregated in a single data structure |
| that is shared by all threads. Huge objects are typically used by |
| applications infrequently enough that this single data structure is not a |
| scalability issue.</para> |
| |
| <para>Each chunk that is managed by an arena tracks its contents as runs of |
| contiguous pages (unused, backing a set of small objects, or backing one |
| large object). The combination of chunk alignment and chunk page maps |
| makes it possible to determine all metadata regarding small and large |
| allocations in constant time.</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 one size class less than |
| the full address space size.</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>Assuming 4 MiB chunks, 4 KiB pages, and a 16-byte quantum on a 64-bit |
| system, the size classes in each category are as shown in <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="8">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, 1024 KiB]</entry> |
| </row> |
| <row> |
| <entry>256 KiB</entry> |
| <entry>[1280 KiB, 1536 KiB, 1792 KiB, 2048 KiB]</entry> |
| </row> |
| <row> |
| <entry>512 KiB</entry> |
| <entry>[2560 KiB, 3072 KiB, 3584 KiB]</entry> |
| </row> |
| <row> |
| <entry morerows="5">Huge</entry> |
| <entry>512 KiB</entry> |
| <entry>[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> |
| </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*<parameter/></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*<parameter/></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.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.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: “disabled”, “primary”, and |
| “secondary”; otherwise only “disabled” is |
| supported. The default is “secondary” if |
| <citerefentry><refentrytitle>sbrk</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> is supported by the operating |
| system; “disabled” 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 4 MiB (2^22). |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.narenas"> |
| <term> |
| <mallctl>opt.narenas</mallctl> |
| (<type>size_t</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.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.</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<parameter/></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<parameter/></function> may |
| allocate memory during application initialization and then deadlock |
| internally when jemalloc in turn calls |
| <function>atexit<parameter/></function>, so this option is not |
| univerally usable (though the application can register its own |
| <function>atexit<parameter/></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>bool</type>) |
| <literal>r-</literal> |
| [<option>--enable-fill</option>] |
| </term> |
| <listitem><para>Junk filling enabled/disabled. If enabled, each byte |
| of uninitialized allocated memory will be initialized to |
| <literal>0xa5</literal>. All deallocated memory will be initialized to |
| <literal>0x5a</literal>. This is intended for debugging and will |
| impact performance negatively. This option is disabled by default |
| unless <option>--enable-debug</option> is specified during |
| configuration, in which case it is enabled 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<parameter/></function> and |
| <function>rallocx<parameter/></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 enabled/disabled. When there |
| are multiple threads, each thread uses a thread-specific cache for |
| objects up to a certain size. Thread-specific caching allows many |
| allocations to be satisfied without performing any thread |
| synchronization, at the cost of increased memory use. See the |
| <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. 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 included <command>pprof</command> Perl script, which originates |
| from the <ulink url="http://code.google.com/p/gperftools/">gperftools |
| package</ulink>.</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>rw</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>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. 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<parameter/></function> may allocate |
| memory during application initialization and then deadlock internally |
| when jemalloc in turn calls <function>atexit<parameter/></function>, so |
| this option is not univerally usable (though the application can |
| register its own <function>atexit<parameter/></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*<parameter/></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*<parameter/></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 |
| lenkend="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 tcache. This interface releases |
| all cached objects and internal data structures associated with the |
| calling thread's thread-specific cache. Ordinarily, this interface |
| need not be called, since automatic periodic incremental garbage |
| collection occurs, and the thread cache is automatically discarded when |
| a thread exits. However, garbage collection is triggered by allocation |
| activity, so it is possible for a thread that stops |
| allocating/deallocating to retain its cache indefinitely, in which case |
| the developer may find manual flushing useful.</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 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="arena.i.purge"> |
| <term> |
| <mallctl>arena.<i>.purge</mallctl> |
| (<type>void</type>) |
| <literal>--</literal> |
| </term> |
| <listitem><para>Purge 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.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.chunk.alloc"> |
| <term> |
| <mallctl>arena.<i>.chunk.alloc</mallctl> |
| (<type>chunk_alloc_t *</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Get or set the chunk allocation function for arena |
| <i>. If setting, the chunk deallocation function should |
| also be set via <link linkend="arena.i.chunk.dalloc"> |
| <mallctl>arena.<i>.chunk.dalloc</mallctl></link> to a companion |
| function that knows how to deallocate the chunks. |
| <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>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| 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 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. |
| Upon error the function returns <constant>NULL</constant> and leaves |
| <parameter>*zero</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. If |
| <parameter>chunk</parameter> is not <constant>NULL</constant>, the |
| returned pointer must be <parameter>chunk</parameter> or |
| <constant>NULL</constant> if it could not be allocated.</para> |
| |
| <para>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></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.chunk.dalloc"> |
| <term> |
| <mallctl>arena.<i>.chunk.dalloc</mallctl> |
| (<type>chunk_dalloc_t *</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Get or set the chunk deallocation function for arena |
| <i>. If setting, the chunk deallocation function must |
| be capable of deallocating all extant chunks associated with arena |
| <i>, usually by passing unknown chunks to the deallocation |
| function that was replaced. 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 allocation/deallocation 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. |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef void <function>(chunk_dalloc_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk</parameter></paramdef> |
| <paramdef>size_t <parameter>size</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| A chunk deallocation function conforms to the |
| <type>chunk_dalloc_t</type> type and deallocates a |
| <parameter>chunk</parameter> of given <parameter>size</parameter> on |
| behalf of arena <parameter>arena_ind</parameter>.</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.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.hchunks.i.size"> |
| <term> |
| <mallctl>arenas.hchunks.<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.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 |
| inverval-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> and pages |
| entirely devoted to allocator metadata.</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 chunks mapped on behalf of the |
| application. This is a multiple of the chunk size, and is at least as |
| large as <link |
| linkend="stats.active"><mallctl>stats.active</mallctl></link>. This |
| does not include inactive chunks.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.chunks.current"> |
| <term> |
| <mallctl>stats.chunks.current</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Total number of chunks actively mapped on behalf of the |
| application. This does not include inactive chunks. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.chunks.total"> |
| <term> |
| <mallctl>stats.chunks.total</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of chunks allocated.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.chunks.high"> |
| <term> |
| <mallctl>stats.chunks.high</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Maximum number of active chunks at any time thus far. |
| </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.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.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="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 “uninitialized” |
| 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<parameter/></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<parameter/></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 |
| “<computeroutput><jemalloc>: </computeroutput>”.</para> |
| </refsect1> |
| <refsect1 id="return_values"> |
| <title>RETURN VALUES</title> |
| <refsect2> |
| <title>Standard API</title> |
| <para>The <function>malloc<parameter/></function> and |
| <function>calloc<parameter/></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<parameter/></function> function |
| returns the value 0 if successful; otherwise it returns an error value. |
| The <function>posix_memalign<parameter/></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<parameter/></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<parameter/></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<parameter/></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<parameter/></function> |
| function always leaves the original buffer intact when an error occurs. |
| </para> |
| |
| <para>The <function>free<parameter/></function> function returns no |
| value.</para> |
| </refsect2> |
| <refsect2> |
| <title>Non-standard API</title> |
| <para>The <function>mallocx<parameter/></function> and |
| <function>rallocx<parameter/></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<parameter/></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<parameter/></function> function returns the |
| real size of the allocation pointed to by <parameter>ptr</parameter>. |
| </para> |
| |
| <para>The <function>nallocx<parameter/></function> returns the real size |
| that would result from a successful equivalent |
| <function>mallocx<parameter/></function> function call, or zero if |
| insufficient memory is available to perform the size computation. </para> |
| |
| <para>The <function>mallctl<parameter/></function>, |
| <function>mallctlnametomib<parameter/></function>, and |
| <function>mallctlbymib<parameter/></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*<parameter/></function> |
| read/write processing.</para></listitem> |
| </varlistentry> |
| </variablelist> |
| </para> |
| |
| <para>The <function>malloc_usable_size<parameter/></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<parameter/></function>, |
| <function>calloc<parameter/></function>, |
| <function>realloc<parameter/></function>, and |
| <function>free<parameter/></function> functions conform to ISO/IEC |
| 9899:1990 (“ISO C90”).</para> |
| |
| <para>The <function>posix_memalign<parameter/></function> function conforms |
| to IEEE Std 1003.1-2001 (“POSIX.1”).</para> |
| </refsect1> |
| </refentry> |