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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 id="MALLOCX_LG_ALIGN"> |
| <term><constant>MALLOCX_LG_ALIGN(<parameter>la</parameter>) |
| </constant></term> |
| |
| <listitem><para>Align the memory allocation to start at an address |
| that is a multiple of <code language="C">(1 << |
| <parameter>la</parameter>)</code>. This macro does not validate |
| that <parameter>la</parameter> is within the valid |
| range.</para></listitem> |
| </varlistentry> |
| <varlistentry id="MALLOCX_ALIGN"> |
| <term><constant>MALLOCX_ALIGN(<parameter>a</parameter>) |
| </constant></term> |
| |
| <listitem><para>Align the memory allocation to start at an address |
| that is a multiple of <parameter>a</parameter>, where |
| <parameter>a</parameter> is a power of two. This macro does not |
| validate that <parameter>a</parameter> is a power of 2. |
| </para></listitem> |
| </varlistentry> |
| <varlistentry id="MALLOCX_ZERO"> |
| <term><constant>MALLOCX_ZERO</constant></term> |
| |
| <listitem><para>Initialize newly allocated memory to contain zero |
| bytes. In the growing reallocation case, the real size prior to |
| reallocation defines the boundary between untouched bytes and those |
| that are initialized to contain zero bytes. If this macro is |
| absent, newly allocated memory is uninitialized.</para></listitem> |
| </varlistentry> |
| <varlistentry id="MALLOCX_TCACHE"> |
| <term><constant>MALLOCX_TCACHE(<parameter>tc</parameter>) |
| </constant></term> |
| |
| <listitem><para>Use the thread-specific cache (tcache) specified by |
| the identifier <parameter>tc</parameter>, which must have been |
| acquired via the <link |
| linkend="tcache.create"><mallctl>tcache.create</mallctl></link> |
| mallctl. This macro does not validate that |
| <parameter>tc</parameter> specifies a valid |
| identifier.</para></listitem> |
| </varlistentry> |
| <varlistentry id="MALLOC_TCACHE_NONE"> |
| <term><constant>MALLOCX_TCACHE_NONE</constant></term> |
| |
| <listitem><para>Do not use a thread-specific cache (tcache). Unless |
| <constant>MALLOCX_TCACHE(<parameter>tc</parameter>)</constant> or |
| <constant>MALLOCX_TCACHE_NONE</constant> is specified, an |
| automatically managed tcache will be used under many circumstances. |
| This macro cannot be used in the same <parameter>flags</parameter> |
| argument as |
| <constant>MALLOCX_TCACHE(<parameter>tc</parameter>)</constant>.</para></listitem> |
| </varlistentry> |
| <varlistentry id="MALLOCX_ARENA"> |
| <term><constant>MALLOCX_ARENA(<parameter>a</parameter>) |
| </constant></term> |
| |
| <listitem><para>Use the arena specified by the index |
| <parameter>a</parameter>. This macro has no effect for regions that |
| were allocated via an arena other than the one specified. This |
| macro does not validate that <parameter>a</parameter> specifies an |
| arena index in the valid range.</para></listitem> |
| </varlistentry> |
| </variablelist> |
| </para> |
| |
| <para>The <function>mallocx<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>.</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>.</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, or |
| <constant>0</constant> if the inputs exceed the maximum supported size |
| class and/or alignment. Behavior is undefined if |
| <parameter>size</parameter> is <constant>0</constant>.</para> |
| |
| <para>The <function>mallctl<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 specified via <option>--with-malloc-conf</option>, 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. <option>--with-malloc-conf</option> |
| and <varname>malloc_conf</varname> are compile-time mechanisms, whereas |
| <filename class="symlink">/etc/malloc.conf</filename> and |
| <envar>MALLOC_CONF</envar> can be safely set any time prior to program |
| invocation.</para> |
| |
| <para>An options string is a comma-separated list of option:value pairs. |
| There is one key corresponding to each <link |
| linkend="opt.abort"><mallctl>opt.*</mallctl></link> mallctl (see the <xref |
| linkend="mallctl_namespace" xrefstyle="template:%t"/> section for options |
| documentation). For example, <literal>abort:true,narenas:1</literal> sets |
| the <link linkend="opt.abort"><mallctl>opt.abort</mallctl></link> and <link |
| linkend="opt.narenas"><mallctl>opt.narenas</mallctl></link> options. Some |
| options have boolean values (true/false), others have integer values (base |
| 8, 10, or 16, depending on prefix), and yet others have raw string |
| values.</para> |
| </refsect1> |
| <refsect1 id="implementation_notes"> |
| <title>IMPLEMENTATION NOTES</title> |
| <para>Traditionally, allocators have used |
| <citerefentry><refentrytitle>sbrk</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> to obtain memory, which is |
| suboptimal for several reasons, including race conditions, increased |
| fragmentation, and artificial limitations on maximum usable memory. If |
| <citerefentry><refentrytitle>sbrk</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> is supported by the operating |
| system, this allocator uses both |
| <citerefentry><refentrytitle>mmap</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> and |
| <citerefentry><refentrytitle>sbrk</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry>, in that order of preference; |
| otherwise only <citerefentry><refentrytitle>mmap</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> is used.</para> |
| |
| <para>This allocator uses multiple arenas in order to reduce lock |
| contention for threaded programs on multi-processor systems. This works |
| well with regard to threading scalability, but incurs some costs. There is |
| a small fixed per-arena overhead, and additionally, arenas manage memory |
| completely independently of each other, which means a small fixed increase |
| in overall memory fragmentation. These overheads are not generally an |
| issue, given the number of arenas normally used. Note that using |
| substantially more arenas than the default is not likely to improve |
| performance, mainly due to reduced cache performance. However, it may make |
| sense to reduce the number of arenas if an application does not make much |
| use of the allocation functions.</para> |
| |
| <para>In addition to multiple arenas, unless |
| <option>--disable-tcache</option> is specified during configuration, this |
| allocator supports thread-specific caching for small and large objects, in |
| order to make it possible to completely avoid synchronization for most |
| allocation requests. Such caching allows very fast allocation in the |
| common case, but it increases memory usage and fragmentation, since a |
| bounded number of objects can remain allocated in each thread cache.</para> |
| |
| <para>Memory is conceptually broken into equal-sized chunks, where the chunk |
| size is a power of two that is greater than the page size. Chunks are |
| always aligned to multiples of the chunk size. This alignment makes it |
| possible to find metadata for user objects very quickly. User objects are |
| broken into three categories according to size: small, large, and huge. |
| Multiple small and large objects can reside within a single chunk, whereas |
| huge objects each have one or more chunks backing them. Each chunk that |
| contains small and/or large objects tracks its contents as runs of |
| contiguous pages (unused, backing a set of small objects, or backing one |
| large object). The combination of chunk alignment and chunk page maps makes |
| it possible to determine all metadata regarding small and large allocations |
| in constant time.</para> |
| |
| <para>Small objects are managed in groups by page runs. Each run maintains |
| a bitmap to track which regions are in use. Allocation requests that are no |
| more than half the quantum (8 or 16, depending on architecture) are rounded |
| up to the nearest power of two that is at least <code |
| language="C">sizeof(<type>double</type>)</code>. All other object size |
| classes are multiples of the quantum, spaced such that there are four size |
| classes for each doubling in size, which limits internal fragmentation to |
| approximately 20% for all but the smallest size classes. Small size classes |
| are smaller than four times the page size, large size classes are smaller |
| than the chunk size (see the <link |
| linkend="opt.lg_chunk"><mallctl>opt.lg_chunk</mallctl></link> option), and |
| huge size classes extend from the chunk size up to the largest size class |
| that does not exceed <constant>PTRDIFF_MAX</constant>.</para> |
| |
| <para>Allocations are packed tightly together, which can be an issue for |
| multi-threaded applications. If you need to assure that allocations do not |
| suffer from cacheline sharing, round your allocation requests up to the |
| nearest multiple of the cacheline size, or specify cacheline alignment when |
| allocating.</para> |
| |
| <para>The <function>realloc<parameter/></function>, |
| <function>rallocx<parameter/></function>, and |
| <function>xallocx<parameter/></function> functions may resize allocations |
| without moving them under limited circumstances. Unlike the |
| <function>*allocx<parameter/></function> API, the standard API does not |
| officially round up the usable size of an allocation to the nearest size |
| class, so technically it is necessary to call |
| <function>realloc<parameter/></function> to grow e.g. a 9-byte allocation to |
| 16 bytes, or shrink a 16-byte allocation to 9 bytes. Growth and shrinkage |
| trivially succeeds in place as long as the pre-size and post-size both round |
| up to the same size class. No other API guarantees are made regarding |
| in-place resizing, but the current implementation also tries to resize large |
| and huge allocations in place, as long as the pre-size and post-size are |
| both large or both huge. In such cases shrinkage always succeeds for large |
| size classes, but for huge size classes the chunk allocator must support |
| splitting (see <link |
| linkend="arena.i.chunk_hooks"><mallctl>arena.<i>.chunk_hooks</mallctl></link>). |
| Growth only succeeds if the trailing memory is currently available, and |
| additionally for huge size classes the chunk allocator must support |
| merging.</para> |
| |
| <para>Assuming 2 MiB chunks, 4 KiB pages, and a 16-byte quantum on a |
| 64-bit system, the size classes in each category are as shown in <xref |
| linkend="size_classes" xrefstyle="template:Table %n"/>.</para> |
| |
| <table xml:id="size_classes" frame="all"> |
| <title>Size classes</title> |
| <tgroup cols="3" colsep="1" rowsep="1"> |
| <colspec colname="c1" align="left"/> |
| <colspec colname="c2" align="right"/> |
| <colspec colname="c3" align="left"/> |
| <thead> |
| <row> |
| <entry>Category</entry> |
| <entry>Spacing</entry> |
| <entry>Size</entry> |
| </row> |
| </thead> |
| <tbody> |
| <row> |
| <entry morerows="8">Small</entry> |
| <entry>lg</entry> |
| <entry>[8]</entry> |
| </row> |
| <row> |
| <entry>16</entry> |
| <entry>[16, 32, 48, 64, 80, 96, 112, 128]</entry> |
| </row> |
| <row> |
| <entry>32</entry> |
| <entry>[160, 192, 224, 256]</entry> |
| </row> |
| <row> |
| <entry>64</entry> |
| <entry>[320, 384, 448, 512]</entry> |
| </row> |
| <row> |
| <entry>128</entry> |
| <entry>[640, 768, 896, 1024]</entry> |
| </row> |
| <row> |
| <entry>256</entry> |
| <entry>[1280, 1536, 1792, 2048]</entry> |
| </row> |
| <row> |
| <entry>512</entry> |
| <entry>[2560, 3072, 3584, 4096]</entry> |
| </row> |
| <row> |
| <entry>1 KiB</entry> |
| <entry>[5 KiB, 6 KiB, 7 KiB, 8 KiB]</entry> |
| </row> |
| <row> |
| <entry>2 KiB</entry> |
| <entry>[10 KiB, 12 KiB, 14 KiB]</entry> |
| </row> |
| <row> |
| <entry morerows="7">Large</entry> |
| <entry>2 KiB</entry> |
| <entry>[16 KiB]</entry> |
| </row> |
| <row> |
| <entry>4 KiB</entry> |
| <entry>[20 KiB, 24 KiB, 28 KiB, 32 KiB]</entry> |
| </row> |
| <row> |
| <entry>8 KiB</entry> |
| <entry>[40 KiB, 48 KiB, 54 KiB, 64 KiB]</entry> |
| </row> |
| <row> |
| <entry>16 KiB</entry> |
| <entry>[80 KiB, 96 KiB, 112 KiB, 128 KiB]</entry> |
| </row> |
| <row> |
| <entry>32 KiB</entry> |
| <entry>[160 KiB, 192 KiB, 224 KiB, 256 KiB]</entry> |
| </row> |
| <row> |
| <entry>64 KiB</entry> |
| <entry>[320 KiB, 384 KiB, 448 KiB, 512 KiB]</entry> |
| </row> |
| <row> |
| <entry>128 KiB</entry> |
| <entry>[640 KiB, 768 KiB, 896 KiB, 1 MiB]</entry> |
| </row> |
| <row> |
| <entry>256 KiB</entry> |
| <entry>[1280 KiB, 1536 KiB, 1792 KiB]</entry> |
| </row> |
| <row> |
| <entry morerows="8">Huge</entry> |
| <entry>256 KiB</entry> |
| <entry>[2 MiB]</entry> |
| </row> |
| <row> |
| <entry>512 KiB</entry> |
| <entry>[2560 KiB, 3 MiB, 3584 KiB, 4 MiB]</entry> |
| </row> |
| <row> |
| <entry>1 MiB</entry> |
| <entry>[5 MiB, 6 MiB, 7 MiB, 8 MiB]</entry> |
| </row> |
| <row> |
| <entry>2 MiB</entry> |
| <entry>[10 MiB, 12 MiB, 14 MiB, 16 MiB]</entry> |
| </row> |
| <row> |
| <entry>4 MiB</entry> |
| <entry>[20 MiB, 24 MiB, 28 MiB, 32 MiB]</entry> |
| </row> |
| <row> |
| <entry>8 MiB</entry> |
| <entry>[40 MiB, 48 MiB, 56 MiB, 64 MiB]</entry> |
| </row> |
| <row> |
| <entry>...</entry> |
| <entry>...</entry> |
| </row> |
| <row> |
| <entry>512 PiB</entry> |
| <entry>[2560 PiB, 3 EiB, 3584 PiB, 4 EiB]</entry> |
| </row> |
| <row> |
| <entry>1 EiB</entry> |
| <entry>[5 EiB, 6 EiB, 7 EiB]</entry> |
| </row> |
| </tbody> |
| </tgroup> |
| </table> |
| </refsect1> |
| <refsect1 id="mallctl_namespace"> |
| <title>MALLCTL NAMESPACE</title> |
| <para>The following names are defined in the namespace accessible via the |
| <function>mallctl*<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.cache_oblivious"> |
| <term> |
| <mallctl>config.cache_oblivious</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-cache-oblivious</option> was specified |
| during build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.debug"> |
| <term> |
| <mallctl>config.debug</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-debug</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.fill"> |
| <term> |
| <mallctl>config.fill</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-fill</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.lazy_lock"> |
| <term> |
| <mallctl>config.lazy_lock</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-lazy-lock</option> was specified |
| during build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.malloc_conf"> |
| <term> |
| <mallctl>config.malloc_conf</mallctl> |
| (<type>const char *</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Embedded configure-time-specified run-time options |
| string, empty unless <option>--with-malloc-conf</option> was specified |
| during build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.munmap"> |
| <term> |
| <mallctl>config.munmap</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-munmap</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.prof"> |
| <term> |
| <mallctl>config.prof</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-prof</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.prof_libgcc"> |
| <term> |
| <mallctl>config.prof_libgcc</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--disable-prof-libgcc</option> was not |
| specified during build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.prof_libunwind"> |
| <term> |
| <mallctl>config.prof_libunwind</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-prof-libunwind</option> was specified |
| during build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.stats"> |
| <term> |
| <mallctl>config.stats</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-stats</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.tcache"> |
| <term> |
| <mallctl>config.tcache</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--disable-tcache</option> was not specified |
| during build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.tls"> |
| <term> |
| <mallctl>config.tls</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--disable-tls</option> was not specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.utrace"> |
| <term> |
| <mallctl>config.utrace</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-utrace</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.valgrind"> |
| <term> |
| <mallctl>config.valgrind</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-valgrind</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="config.xmalloc"> |
| <term> |
| <mallctl>config.xmalloc</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para><option>--enable-xmalloc</option> was specified during |
| build configuration.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.abort"> |
| <term> |
| <mallctl>opt.abort</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Abort-on-warning enabled/disabled. If true, most |
| warnings are fatal. The process will call |
| <citerefentry><refentrytitle>abort</refentrytitle> |
| <manvolnum>3</manvolnum></citerefentry> in these cases. This option is |
| disabled by default unless <option>--enable-debug</option> is |
| specified during configuration, in which case it is enabled by default. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.dss"> |
| <term> |
| <mallctl>opt.dss</mallctl> |
| (<type>const char *</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>dss (<citerefentry><refentrytitle>sbrk</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry>) allocation precedence as |
| related to <citerefentry><refentrytitle>mmap</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> allocation. The following |
| settings are supported if |
| <citerefentry><refentrytitle>sbrk</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> is supported by the operating |
| system: “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 2 MiB (2^21). |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.narenas"> |
| <term> |
| <mallctl>opt.narenas</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Maximum number of arenas to use for automatic |
| multiplexing of threads and arenas. The default is four times the |
| number of CPUs, or one if there is a single CPU.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.purge"> |
| <term> |
| <mallctl>opt.purge</mallctl> |
| (<type>const char *</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Purge mode is “ratio” (default) or |
| “decay”. See <link |
| linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> |
| for details of the ratio mode. See <link |
| linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for |
| details of the decay mode.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.lg_dirty_mult"> |
| <term> |
| <mallctl>opt.lg_dirty_mult</mallctl> |
| (<type>ssize_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Per-arena minimum ratio (log base 2) of active to dirty |
| pages. Some dirty unused pages may be allowed to accumulate, within |
| the limit set by the ratio (or one chunk worth of dirty pages, |
| whichever is greater), before informing the kernel about some of those |
| pages via <citerefentry><refentrytitle>madvise</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> or a similar system call. This |
| provides the kernel with sufficient information to recycle dirty pages |
| if physical memory becomes scarce and the pages remain unused. The |
| default minimum ratio is 8:1 (2^3:1); an option value of -1 will |
| disable dirty page purging. See <link |
| linkend="arenas.lg_dirty_mult"><mallctl>arenas.lg_dirty_mult</mallctl></link> |
| and <link |
| linkend="arena.i.lg_dirty_mult"><mallctl>arena.<i>.lg_dirty_mult</mallctl></link> |
| for related dynamic control options.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.decay_time"> |
| <term> |
| <mallctl>opt.decay_time</mallctl> |
| (<type>ssize_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Approximate time in seconds from the creation of a set |
| of unused dirty pages until an equivalent set of unused dirty pages is |
| purged and/or reused. The pages are incrementally purged according to a |
| sigmoidal decay curve that starts and ends with zero purge rate. A |
| decay time of 0 causes all unused dirty pages to be purged immediately |
| upon creation. A decay time of -1 disables purging. The default decay |
| time is 10 seconds. See <link |
| linkend="arenas.decay_time"><mallctl>arenas.decay_time</mallctl></link> |
| and <link |
| linkend="arena.i.decay_time"><mallctl>arena.<i>.decay_time</mallctl></link> |
| for related dynamic control options. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.stats_print"> |
| <term> |
| <mallctl>opt.stats_print</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Enable/disable statistics printing at exit. If |
| enabled, the <function>malloc_stats_print<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 |
| universally 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>const char *</type>) |
| <literal>r-</literal> |
| [<option>--enable-fill</option>] |
| </term> |
| <listitem><para>Junk filling. If set to "alloc", each byte of |
| uninitialized allocated memory will be initialized to |
| <literal>0xa5</literal>. If set to "free", all deallocated memory will |
| be initialized to <literal>0x5a</literal>. If set to "true", both |
| allocated and deallocated memory will be initialized, and if set to |
| "false", junk filling be disabled entirely. This is intended for |
| debugging and will impact performance negatively. This option is |
| "false" by default unless <option>--enable-debug</option> is specified |
| during configuration, in which case it is "true" 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 (tcache) enabled/disabled. When |
| there are multiple threads, each thread uses a tcache for objects up to |
| a certain size. Thread-specific caching allows many allocations to be |
| satisfied without performing any thread synchronization, at the cost of |
| increased memory use. See the <link |
| linkend="opt.lg_tcache_max"><mallctl>opt.lg_tcache_max</mallctl></link> |
| option for related tuning information. This option is enabled by |
| default unless running inside <ulink |
| url="http://valgrind.org/">Valgrind</ulink>, in which case it is |
| forcefully disabled.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.lg_tcache_max"> |
| <term> |
| <mallctl>opt.lg_tcache_max</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Maximum size class (log base 2) to cache in the |
| thread-specific cache (tcache). At a minimum, all small size classes |
| are cached, and at a maximum all large size classes are cached. The |
| default maximum is 32 KiB (2^15).</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.prof"> |
| <term> |
| <mallctl>opt.prof</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Memory profiling enabled/disabled. If enabled, profile |
| memory allocation activity. See the <link |
| linkend="opt.prof_active"><mallctl>opt.prof_active</mallctl></link> |
| option for on-the-fly activation/deactivation. See the <link |
| linkend="opt.lg_prof_sample"><mallctl>opt.lg_prof_sample</mallctl></link> |
| option for probabilistic sampling control. See the <link |
| linkend="opt.prof_accum"><mallctl>opt.prof_accum</mallctl></link> |
| option for control of cumulative sample reporting. See the <link |
| linkend="opt.lg_prof_interval"><mallctl>opt.lg_prof_interval</mallctl></link> |
| option for information on interval-triggered profile dumping, the <link |
| linkend="opt.prof_gdump"><mallctl>opt.prof_gdump</mallctl></link> |
| option for information on high-water-triggered profile dumping, and the |
| <link linkend="opt.prof_final"><mallctl>opt.prof_final</mallctl></link> |
| option for final profile dumping. Profile output is compatible with |
| the <command>jeprof</command> command, which is based on the |
| <command>pprof</command> that is developed as part of the <ulink |
| url="http://code.google.com/p/gperftools/">gperftools |
| package</ulink>. See <link linkend="heap_profile_format">HEAP PROFILE |
| FORMAT</link> for heap profile format documentation.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.prof_prefix"> |
| <term> |
| <mallctl>opt.prof_prefix</mallctl> |
| (<type>const char *</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Filename prefix for profile dumps. If the prefix is |
| set to the empty string, no automatic dumps will occur; this is |
| primarily useful for disabling the automatic final heap dump (which |
| also disables leak reporting, if enabled). The default prefix is |
| <filename>jeprof</filename>.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.prof_active"> |
| <term> |
| <mallctl>opt.prof_active</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Profiling activated/deactivated. This is a secondary |
| control mechanism that makes it possible to start the application with |
| profiling enabled (see the <link |
| linkend="opt.prof"><mallctl>opt.prof</mallctl></link> option) but |
| inactive, then toggle profiling at any time during program execution |
| with the <link |
| linkend="prof.active"><mallctl>prof.active</mallctl></link> mallctl. |
| This option is enabled by default.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.prof_thread_active_init"> |
| <term> |
| <mallctl>opt.prof_thread_active_init</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Initial setting for <link |
| linkend="thread.prof.active"><mallctl>thread.prof.active</mallctl></link> |
| in newly created threads. The initial setting for newly created threads |
| can also be changed during execution via the <link |
| linkend="prof.thread_active_init"><mallctl>prof.thread_active_init</mallctl></link> |
| mallctl. This option is enabled by default.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.lg_prof_sample"> |
| <term> |
| <mallctl>opt.lg_prof_sample</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Average interval (log base 2) between allocation |
| samples, as measured in bytes of allocation activity. Increasing the |
| sampling interval decreases profile fidelity, but also decreases the |
| computational overhead. The default sample interval is 512 KiB (2^19 |
| B).</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.prof_accum"> |
| <term> |
| <mallctl>opt.prof_accum</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Reporting of cumulative object/byte counts in profile |
| dumps enabled/disabled. If this option is enabled, every unique |
| backtrace must be stored for the duration of execution. Depending on |
| the application, this can impose a large memory overhead, and the |
| cumulative counts are not always of interest. This option is disabled |
| by default.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.lg_prof_interval"> |
| <term> |
| <mallctl>opt.lg_prof_interval</mallctl> |
| (<type>ssize_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Average interval (log base 2) between memory profile |
| dumps, as measured in bytes of allocation activity. The actual |
| interval between dumps may be sporadic because decentralized allocation |
| counters are used to avoid synchronization bottlenecks. Profiles are |
| dumped to files named according to the pattern |
| <filename><prefix>.<pid>.<seq>.i<iseq>.heap</filename>, |
| where <literal><prefix></literal> is controlled by the |
| <link |
| linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> |
| option. By default, interval-triggered profile dumping is disabled |
| (encoded as -1). |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.prof_gdump"> |
| <term> |
| <mallctl>opt.prof_gdump</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Set the initial state of <link |
| linkend="prof.gdump"><mallctl>prof.gdump</mallctl></link>, which when |
| enabled triggers a memory profile dump every time the total virtual |
| memory exceeds the previous maximum. This option is disabled by |
| default.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="opt.prof_final"> |
| <term> |
| <mallctl>opt.prof_final</mallctl> |
| (<type>bool</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Use an |
| <citerefentry><refentrytitle>atexit</refentrytitle> |
| <manvolnum>3</manvolnum></citerefentry> function to dump final memory |
| usage to a file named according to the pattern |
| <filename><prefix>.<pid>.<seq>.f.heap</filename>, |
| where <literal><prefix></literal> is controlled by the <link |
| linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> |
| option. Note that <function>atexit<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 universally 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 |
| linkend="thread.tcache.flush"><mallctl>thread.tcache.flush</mallctl></link>). |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="thread.tcache.flush"> |
| <term> |
| <mallctl>thread.tcache.flush</mallctl> |
| (<type>void</type>) |
| <literal>--</literal> |
| [<option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Flush calling thread's thread-specific cache (tcache). |
| This interface releases all cached objects and internal data structures |
| associated with the calling thread's tcache. Ordinarily, this interface |
| need not be called, since automatic periodic incremental garbage |
| collection occurs, and the thread cache is automatically discarded when |
| a thread exits. However, garbage collection is triggered by allocation |
| activity, so it is possible for a thread that stops |
| allocating/deallocating to retain its cache indefinitely, in which case |
| the developer may find manual flushing useful.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="thread.prof.name"> |
| <term> |
| <mallctl>thread.prof.name</mallctl> |
| (<type>const char *</type>) |
| <literal>r-</literal> or |
| <literal>-w</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Get/set the descriptive name associated with the calling |
| thread in memory profile dumps. An internal copy of the name string is |
| created, so the input string need not be maintained after this interface |
| completes execution. The output string of this interface should be |
| copied for non-ephemeral uses, because multiple implementation details |
| can cause asynchronous string deallocation. Furthermore, each |
| invocation of this interface can only read or write; simultaneous |
| read/write is not supported due to string lifetime limitations. The |
| name string must be nil-terminated and comprised only of characters in |
| the sets recognized |
| by <citerefentry><refentrytitle>isgraph</refentrytitle> |
| <manvolnum>3</manvolnum></citerefentry> and |
| <citerefentry><refentrytitle>isblank</refentrytitle> |
| <manvolnum>3</manvolnum></citerefentry>.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="thread.prof.active"> |
| <term> |
| <mallctl>thread.prof.active</mallctl> |
| (<type>bool</type>) |
| <literal>rw</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Control whether sampling is currently active for the |
| calling thread. This is an activation mechanism in addition to <link |
| linkend="prof.active"><mallctl>prof.active</mallctl></link>; both must |
| be active for the calling thread to sample. This flag is enabled by |
| default.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="tcache.create"> |
| <term> |
| <mallctl>tcache.create</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| [<option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Create an explicit thread-specific cache (tcache) and |
| return an identifier that can be passed to the <link |
| linkend="MALLOCX_TCACHE"><constant>MALLOCX_TCACHE(<parameter>tc</parameter>)</constant></link> |
| macro to explicitly use the specified cache rather than the |
| automatically managed one that is used by default. Each explicit cache |
| can be used by only one thread at a time; the application must assure |
| that this constraint holds. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="tcache.flush"> |
| <term> |
| <mallctl>tcache.flush</mallctl> |
| (<type>unsigned</type>) |
| <literal>-w</literal> |
| [<option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Flush the specified thread-specific cache (tcache). The |
| same considerations apply to this interface as to <link |
| linkend="thread.tcache.flush"><mallctl>thread.tcache.flush</mallctl></link>, |
| except that the tcache will never be automatically discarded. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="tcache.destroy"> |
| <term> |
| <mallctl>tcache.destroy</mallctl> |
| (<type>unsigned</type>) |
| <literal>-w</literal> |
| [<option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Flush the specified thread-specific cache (tcache) and |
| make the identifier available for use during a future tcache creation. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.purge"> |
| <term> |
| <mallctl>arena.<i>.purge</mallctl> |
| (<type>void</type>) |
| <literal>--</literal> |
| </term> |
| <listitem><para>Purge all unused dirty pages for arena <i>, or for |
| all arenas if <i> equals <link |
| linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.decay"> |
| <term> |
| <mallctl>arena.<i>.decay</mallctl> |
| (<type>void</type>) |
| <literal>--</literal> |
| </term> |
| <listitem><para>Trigger decay-based purging of unused dirty pages for |
| arena <i>, or for all arenas if <i> equals <link |
| linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>. |
| The proportion of unused dirty pages to be purged depends on the current |
| time; see <link |
| linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for |
| details.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.reset"> |
| <term> |
| <mallctl>arena.<i>.reset</mallctl> |
| (<type>void</type>) |
| <literal>--</literal> |
| </term> |
| <listitem><para>Discard all of the arena's extant allocations. This |
| interface can only be used with arenas created via <link |
| linkend="arenas.extend"><mallctl>arenas.extend</mallctl></link>. None |
| of the arena's discarded/cached allocations may accessed afterward. As |
| part of this requirement, all thread caches which were used to |
| allocate/deallocate in conjunction with the arena must be flushed |
| beforehand. This interface cannot be used if running inside Valgrind, |
| nor if the <link linkend="opt.quarantine">quarantine</link> size is |
| non-zero.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.dss"> |
| <term> |
| <mallctl>arena.<i>.dss</mallctl> |
| (<type>const char *</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Set the precedence of dss allocation as related to mmap |
| allocation for arena <i>, or for all arenas if <i> equals |
| <link |
| linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link>. See |
| <link linkend="opt.dss"><mallctl>opt.dss</mallctl></link> for supported |
| settings.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.lg_dirty_mult"> |
| <term> |
| <mallctl>arena.<i>.lg_dirty_mult</mallctl> |
| (<type>ssize_t</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Current per-arena minimum ratio (log base 2) of active |
| to dirty pages for arena <i>. Each time this interface is set and |
| the ratio is increased, pages are synchronously purged as necessary to |
| impose the new ratio. See <link |
| linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> |
| for additional information.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.decay_time"> |
| <term> |
| <mallctl>arena.<i>.decay_time</mallctl> |
| (<type>ssize_t</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Current per-arena approximate time in seconds from the |
| creation of a set of unused dirty pages until an equivalent set of |
| unused dirty pages is purged and/or reused. Each time this interface is |
| set, all currently unused dirty pages are considered to have fully |
| decayed, which causes immediate purging of all unused dirty pages unless |
| the decay time is set to -1 (i.e. purging disabled). See <link |
| linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for |
| additional information.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arena.i.chunk_hooks"> |
| <term> |
| <mallctl>arena.<i>.chunk_hooks</mallctl> |
| (<type>chunk_hooks_t</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Get or set the chunk management hook functions for arena |
| <i>. The functions must be capable of operating on all extant |
| chunks associated with arena <i>, usually by passing unknown |
| chunks to the replaced functions. In practice, it is feasible to |
| control allocation for arenas created via <link |
| linkend="arenas.extend"><mallctl>arenas.extend</mallctl></link> such |
| that all chunks originate from an application-supplied chunk allocator |
| (by setting custom chunk hook functions just after arena creation), but |
| the automatically created arenas may have already created chunks prior |
| to the application having an opportunity to take over chunk |
| allocation.</para> |
| |
| <programlisting language="C"><![CDATA[ |
| typedef struct { |
| chunk_alloc_t *alloc; |
| chunk_dalloc_t *dalloc; |
| chunk_commit_t *commit; |
| chunk_decommit_t *decommit; |
| chunk_purge_t *purge; |
| chunk_split_t *split; |
| chunk_merge_t *merge; |
| } chunk_hooks_t;]]></programlisting> |
| <para>The <type>chunk_hooks_t</type> structure comprises function |
| pointers which are described individually below. jemalloc uses these |
| functions to manage chunk lifetime, which starts off with allocation of |
| mapped committed memory, in the simplest case followed by deallocation. |
| However, there are performance and platform reasons to retain chunks for |
| later reuse. Cleanup attempts cascade from deallocation to decommit to |
| purging, which gives the chunk management functions opportunities to |
| reject the most permanent cleanup operations in favor of less permanent |
| (and often less costly) operations. The chunk splitting and merging |
| operations can also be opted out of, but this is mainly intended to |
| support platforms on which virtual memory mappings provided by the |
| operating system kernel do not automatically coalesce and split, e.g. |
| Windows.</para> |
| |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef void *<function>(chunk_alloc_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk</parameter></paramdef> |
| <paramdef>size_t <parameter>size</parameter></paramdef> |
| <paramdef>size_t <parameter>alignment</parameter></paramdef> |
| <paramdef>bool *<parameter>zero</parameter></paramdef> |
| <paramdef>bool *<parameter>commit</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| <literallayout></literallayout> |
| <para>A chunk allocation function conforms to the |
| <type>chunk_alloc_t</type> type and upon success returns a pointer to |
| <parameter>size</parameter> bytes of mapped memory on behalf of arena |
| <parameter>arena_ind</parameter> such that the chunk's base address is a |
| multiple of <parameter>alignment</parameter>, as well as setting |
| <parameter>*zero</parameter> to indicate whether the chunk is zeroed and |
| <parameter>*commit</parameter> to indicate whether the chunk is |
| committed. Upon error the function returns <constant>NULL</constant> |
| and leaves <parameter>*zero</parameter> and |
| <parameter>*commit</parameter> unmodified. The |
| <parameter>size</parameter> parameter is always a multiple of the chunk |
| size. The <parameter>alignment</parameter> parameter is always a power |
| of two at least as large as the chunk size. Zeroing is mandatory if |
| <parameter>*zero</parameter> is true upon function entry. Committing is |
| mandatory if <parameter>*commit</parameter> is true upon function entry. |
| If <parameter>chunk</parameter> is not <constant>NULL</constant>, the |
| returned pointer must be <parameter>chunk</parameter> on success or |
| <constant>NULL</constant> on error. Committed memory may be committed |
| in absolute terms as on a system that does not overcommit, or in |
| implicit terms as on a system that overcommits and satisfies physical |
| memory needs on demand via soft page faults. Note that replacing the |
| default chunk allocation function makes the arena's <link |
| linkend="arena.i.dss"><mallctl>arena.<i>.dss</mallctl></link> |
| setting irrelevant.</para> |
| |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef bool <function>(chunk_dalloc_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk</parameter></paramdef> |
| <paramdef>size_t <parameter>size</parameter></paramdef> |
| <paramdef>bool <parameter>committed</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| <literallayout></literallayout> |
| <para> |
| A chunk deallocation function conforms to the |
| <type>chunk_dalloc_t</type> type and deallocates a |
| <parameter>chunk</parameter> of given <parameter>size</parameter> with |
| <parameter>committed</parameter>/decommited memory as indicated, on |
| behalf of arena <parameter>arena_ind</parameter>, returning false upon |
| success. If the function returns true, this indicates opt-out from |
| deallocation; the virtual memory mapping associated with the chunk |
| remains mapped, in the same commit state, and available for future use, |
| in which case it will be automatically retained for later reuse.</para> |
| |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef bool <function>(chunk_commit_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk</parameter></paramdef> |
| <paramdef>size_t <parameter>size</parameter></paramdef> |
| <paramdef>size_t <parameter>offset</parameter></paramdef> |
| <paramdef>size_t <parameter>length</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| <literallayout></literallayout> |
| <para>A chunk commit function conforms to the |
| <type>chunk_commit_t</type> type and commits zeroed physical memory to |
| back pages within a <parameter>chunk</parameter> of given |
| <parameter>size</parameter> at <parameter>offset</parameter> bytes, |
| extending for <parameter>length</parameter> on behalf of arena |
| <parameter>arena_ind</parameter>, returning false upon success. |
| Committed memory may be committed in absolute terms as on a system that |
| does not overcommit, or in implicit terms as on a system that |
| overcommits and satisfies physical memory needs on demand via soft page |
| faults. If the function returns true, this indicates insufficient |
| physical memory to satisfy the request.</para> |
| |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef bool <function>(chunk_decommit_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk</parameter></paramdef> |
| <paramdef>size_t <parameter>size</parameter></paramdef> |
| <paramdef>size_t <parameter>offset</parameter></paramdef> |
| <paramdef>size_t <parameter>length</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| <literallayout></literallayout> |
| <para>A chunk decommit function conforms to the |
| <type>chunk_decommit_t</type> type and decommits any physical memory |
| that is backing pages within a <parameter>chunk</parameter> of given |
| <parameter>size</parameter> at <parameter>offset</parameter> bytes, |
| extending for <parameter>length</parameter> on behalf of arena |
| <parameter>arena_ind</parameter>, returning false upon success, in which |
| case the pages will be committed via the chunk commit function before |
| being reused. If the function returns true, this indicates opt-out from |
| decommit; the memory remains committed and available for future use, in |
| which case it will be automatically retained for later reuse.</para> |
| |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef bool <function>(chunk_purge_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk</parameter></paramdef> |
| <paramdef>size_t<parameter>size</parameter></paramdef> |
| <paramdef>size_t <parameter>offset</parameter></paramdef> |
| <paramdef>size_t <parameter>length</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| <literallayout></literallayout> |
| <para>A chunk purge function conforms to the <type>chunk_purge_t</type> |
| type and optionally discards physical pages within the virtual memory |
| mapping associated with <parameter>chunk</parameter> of given |
| <parameter>size</parameter> at <parameter>offset</parameter> bytes, |
| extending for <parameter>length</parameter> on behalf of arena |
| <parameter>arena_ind</parameter>, returning false if pages within the |
| purged virtual memory range will be zero-filled the next time they are |
| accessed.</para> |
| |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef bool <function>(chunk_split_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk</parameter></paramdef> |
| <paramdef>size_t <parameter>size</parameter></paramdef> |
| <paramdef>size_t <parameter>size_a</parameter></paramdef> |
| <paramdef>size_t <parameter>size_b</parameter></paramdef> |
| <paramdef>bool <parameter>committed</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| <literallayout></literallayout> |
| <para>A chunk split function conforms to the <type>chunk_split_t</type> |
| type and optionally splits <parameter>chunk</parameter> of given |
| <parameter>size</parameter> into two adjacent chunks, the first of |
| <parameter>size_a</parameter> bytes, and the second of |
| <parameter>size_b</parameter> bytes, operating on |
| <parameter>committed</parameter>/decommitted memory as indicated, on |
| behalf of arena <parameter>arena_ind</parameter>, returning false upon |
| success. If the function returns true, this indicates that the chunk |
| remains unsplit and therefore should continue to be operated on as a |
| whole.</para> |
| |
| <funcsynopsis><funcprototype> |
| <funcdef>typedef bool <function>(chunk_merge_t)</function></funcdef> |
| <paramdef>void *<parameter>chunk_a</parameter></paramdef> |
| <paramdef>size_t <parameter>size_a</parameter></paramdef> |
| <paramdef>void *<parameter>chunk_b</parameter></paramdef> |
| <paramdef>size_t <parameter>size_b</parameter></paramdef> |
| <paramdef>bool <parameter>committed</parameter></paramdef> |
| <paramdef>unsigned <parameter>arena_ind</parameter></paramdef> |
| </funcprototype></funcsynopsis> |
| <literallayout></literallayout> |
| <para>A chunk merge function conforms to the <type>chunk_merge_t</type> |
| type and optionally merges adjacent chunks, |
| <parameter>chunk_a</parameter> of given <parameter>size_a</parameter> |
| and <parameter>chunk_b</parameter> of given |
| <parameter>size_b</parameter> into one contiguous chunk, operating on |
| <parameter>committed</parameter>/decommitted memory as indicated, on |
| behalf of arena <parameter>arena_ind</parameter>, returning false upon |
| success. If the function returns true, this indicates that the chunks |
| remain distinct mappings and therefore should continue to be operated on |
| independently.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.narenas"> |
| <term> |
| <mallctl>arenas.narenas</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Current limit on number of arenas.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.initialized"> |
| <term> |
| <mallctl>arenas.initialized</mallctl> |
| (<type>bool *</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>An array of <link |
| linkend="arenas.narenas"><mallctl>arenas.narenas</mallctl></link> |
| booleans. Each boolean indicates whether the corresponding arena is |
| initialized.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.lg_dirty_mult"> |
| <term> |
| <mallctl>arenas.lg_dirty_mult</mallctl> |
| (<type>ssize_t</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Current default per-arena minimum ratio (log base 2) of |
| active to dirty pages, used to initialize <link |
| linkend="arena.i.lg_dirty_mult"><mallctl>arena.<i>.lg_dirty_mult</mallctl></link> |
| during arena creation. See <link |
| linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> |
| for additional information.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.decay_time"> |
| <term> |
| <mallctl>arenas.decay_time</mallctl> |
| (<type>ssize_t</type>) |
| <literal>rw</literal> |
| </term> |
| <listitem><para>Current default per-arena approximate time in seconds |
| from the creation of a set of unused dirty pages until an equivalent set |
| of unused dirty pages is purged and/or reused, used to initialize <link |
| linkend="arena.i.decay_time"><mallctl>arena.<i>.decay_time</mallctl></link> |
| during arena creation. See <link |
| linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> for |
| additional information.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.quantum"> |
| <term> |
| <mallctl>arenas.quantum</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Quantum size.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.page"> |
| <term> |
| <mallctl>arenas.page</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Page size.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.tcache_max"> |
| <term> |
| <mallctl>arenas.tcache_max</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Maximum thread-cached size class.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.nbins"> |
| <term> |
| <mallctl>arenas.nbins</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Number of bin size classes.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.nhbins"> |
| <term> |
| <mallctl>arenas.nhbins</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| [<option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Total number of thread cache bin size |
| classes.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.bin.i.size"> |
| <term> |
| <mallctl>arenas.bin.<i>.size</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Maximum size supported by size class.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.bin.i.nregs"> |
| <term> |
| <mallctl>arenas.bin.<i>.nregs</mallctl> |
| (<type>uint32_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Number of regions per page run.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.bin.i.run_size"> |
| <term> |
| <mallctl>arenas.bin.<i>.run_size</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Number of bytes per page run.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.nlruns"> |
| <term> |
| <mallctl>arenas.nlruns</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Total number of large size classes.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.lrun.i.size"> |
| <term> |
| <mallctl>arenas.lrun.<i>.size</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Maximum size supported by this large size |
| class.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.nhchunks"> |
| <term> |
| <mallctl>arenas.nhchunks</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Total number of huge size classes.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.hchunk.i.size"> |
| <term> |
| <mallctl>arenas.hchunk.<i>.size</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Maximum size supported by this huge size |
| class.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="arenas.extend"> |
| <term> |
| <mallctl>arenas.extend</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Extend the array of arenas by appending a new arena, |
| and returning the new arena index.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="prof.thread_active_init"> |
| <term> |
| <mallctl>prof.thread_active_init</mallctl> |
| (<type>bool</type>) |
| <literal>rw</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Control the initial setting for <link |
| linkend="thread.prof.active"><mallctl>thread.prof.active</mallctl></link> |
| in newly created threads. See the <link |
| linkend="opt.prof_thread_active_init"><mallctl>opt.prof_thread_active_init</mallctl></link> |
| option for additional information.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="prof.active"> |
| <term> |
| <mallctl>prof.active</mallctl> |
| (<type>bool</type>) |
| <literal>rw</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Control whether sampling is currently active. See the |
| <link |
| linkend="opt.prof_active"><mallctl>opt.prof_active</mallctl></link> |
| option for additional information, as well as the interrelated <link |
| linkend="thread.prof.active"><mallctl>thread.prof.active</mallctl></link> |
| mallctl.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="prof.dump"> |
| <term> |
| <mallctl>prof.dump</mallctl> |
| (<type>const char *</type>) |
| <literal>-w</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Dump a memory profile to the specified file, or if NULL |
| is specified, to a file according to the pattern |
| <filename><prefix>.<pid>.<seq>.m<mseq>.heap</filename>, |
| where <literal><prefix></literal> is controlled by the |
| <link |
| linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> |
| option.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="prof.gdump"> |
| <term> |
| <mallctl>prof.gdump</mallctl> |
| (<type>bool</type>) |
| <literal>rw</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>When enabled, trigger a memory profile dump every time |
| the total virtual memory exceeds the previous maximum. Profiles are |
| dumped to files named according to the pattern |
| <filename><prefix>.<pid>.<seq>.u<useq>.heap</filename>, |
| where <literal><prefix></literal> is controlled by the <link |
| linkend="opt.prof_prefix"><mallctl>opt.prof_prefix</mallctl></link> |
| option.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="prof.reset"> |
| <term> |
| <mallctl>prof.reset</mallctl> |
| (<type>size_t</type>) |
| <literal>-w</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Reset all memory profile statistics, and optionally |
| update the sample rate (see <link |
| linkend="opt.lg_prof_sample"><mallctl>opt.lg_prof_sample</mallctl></link> |
| and <link |
| linkend="prof.lg_sample"><mallctl>prof.lg_sample</mallctl></link>). |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="prof.lg_sample"> |
| <term> |
| <mallctl>prof.lg_sample</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Get the current sample rate (see <link |
| linkend="opt.lg_prof_sample"><mallctl>opt.lg_prof_sample</mallctl></link>). |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="prof.interval"> |
| <term> |
| <mallctl>prof.interval</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-prof</option>] |
| </term> |
| <listitem><para>Average number of bytes allocated between |
| interval-based profile dumps. See the |
| <link |
| linkend="opt.lg_prof_interval"><mallctl>opt.lg_prof_interval</mallctl></link> |
| option for additional information.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.cactive"> |
| <term> |
| <mallctl>stats.cactive</mallctl> |
| (<type>size_t *</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Pointer to a counter that contains an approximate count |
| of the current number of bytes in active pages. The estimate may be |
| high, but never low, because each arena rounds up when computing its |
| contribution to the counter. Note that the <link |
| linkend="epoch"><mallctl>epoch</mallctl></link> mallctl has no bearing |
| on this counter. Furthermore, counter consistency is maintained via |
| atomic operations, so it is necessary to use an atomic operation in |
| order to guarantee a consistent read when dereferencing the pointer. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.allocated"> |
| <term> |
| <mallctl>stats.allocated</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Total number of bytes allocated by the |
| application.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.active"> |
| <term> |
| <mallctl>stats.active</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Total number of bytes in active pages allocated by the |
| application. This is a multiple of the page size, and greater than or |
| equal to <link |
| linkend="stats.allocated"><mallctl>stats.allocated</mallctl></link>. |
| This does not include <link linkend="stats.arenas.i.pdirty"> |
| <mallctl>stats.arenas.<i>.pdirty</mallctl></link>, nor pages |
| entirely devoted to allocator metadata.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.metadata"> |
| <term> |
| <mallctl>stats.metadata</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Total number of bytes dedicated to metadata, which |
| comprise base allocations used for bootstrap-sensitive internal |
| allocator data structures, arena chunk headers (see <link |
| linkend="stats.arenas.i.metadata.mapped"><mallctl>stats.arenas.<i>.metadata.mapped</mallctl></link>), |
| and internal allocations (see <link |
| linkend="stats.arenas.i.metadata.allocated"><mallctl>stats.arenas.<i>.metadata.allocated</mallctl></link>).</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.resident"> |
| <term> |
| <mallctl>stats.resident</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Maximum number of bytes in physically resident data |
| pages mapped by the allocator, comprising all pages dedicated to |
| allocator metadata, pages backing active allocations, and unused dirty |
| pages. This is a maximum rather than precise because pages may not |
| actually be physically resident if they correspond to demand-zeroed |
| virtual memory that has not yet been touched. This is a multiple of the |
| page size, and is larger than <link |
| linkend="stats.active"><mallctl>stats.active</mallctl></link>.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.mapped"> |
| <term> |
| <mallctl>stats.mapped</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Total number of bytes in active chunks mapped by the |
| allocator. This is a multiple of the chunk size, and is larger than |
| <link linkend="stats.active"><mallctl>stats.active</mallctl></link>. |
| This does not include inactive chunks, even those that contain unused |
| dirty pages, which means that there is no strict ordering between this |
| and <link |
| linkend="stats.resident"><mallctl>stats.resident</mallctl></link>.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.retained"> |
| <term> |
| <mallctl>stats.retained</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Total number of bytes in virtual memory mappings that |
| were retained rather than being returned to the operating system via |
| e.g. <citerefentry><refentrytitle>munmap</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry>. Retained virtual memory is |
| typically untouched, decommitted, or purged, so it has no strongly |
| associated physical memory (see <link |
| linkend="arena.i.chunk_hooks">chunk hooks</link> for details). Retained |
| memory is excluded from mapped memory statistics, e.g. <link |
| linkend="stats.mapped"><mallctl>stats.mapped</mallctl></link>. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.dss"> |
| <term> |
| <mallctl>stats.arenas.<i>.dss</mallctl> |
| (<type>const char *</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>dss (<citerefentry><refentrytitle>sbrk</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry>) allocation precedence as |
| related to <citerefentry><refentrytitle>mmap</refentrytitle> |
| <manvolnum>2</manvolnum></citerefentry> allocation. See <link |
| linkend="opt.dss"><mallctl>opt.dss</mallctl></link> for details. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.lg_dirty_mult"> |
| <term> |
| <mallctl>stats.arenas.<i>.lg_dirty_mult</mallctl> |
| (<type>ssize_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Minimum ratio (log base 2) of active to dirty pages. |
| See <link |
| linkend="opt.lg_dirty_mult"><mallctl>opt.lg_dirty_mult</mallctl></link> |
| for details.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.decay_time"> |
| <term> |
| <mallctl>stats.arenas.<i>.decay_time</mallctl> |
| (<type>ssize_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Approximate time in seconds from the creation of a set |
| of unused dirty pages until an equivalent set of unused dirty pages is |
| purged and/or reused. See <link |
| linkend="opt.decay_time"><mallctl>opt.decay_time</mallctl></link> |
| for details.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.nthreads"> |
| <term> |
| <mallctl>stats.arenas.<i>.nthreads</mallctl> |
| (<type>unsigned</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Number of threads currently assigned to |
| arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.pactive"> |
| <term> |
| <mallctl>stats.arenas.<i>.pactive</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Number of pages in active runs.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.pdirty"> |
| <term> |
| <mallctl>stats.arenas.<i>.pdirty</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| </term> |
| <listitem><para>Number of pages within unused runs that are potentially |
| dirty, and for which <function>madvise<parameter>...</parameter> |
| <parameter><constant>MADV_DONTNEED</constant></parameter></function> or |
| similar has not been called.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.mapped"> |
| <term> |
| <mallctl>stats.arenas.<i>.mapped</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of mapped bytes.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.retained"> |
| <term> |
| <mallctl>stats.arenas.<i>.retained</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of retained bytes. See <link |
| linkend="stats.retained"><mallctl>stats.retained</mallctl></link> for |
| details.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.metadata.mapped"> |
| <term> |
| <mallctl>stats.arenas.<i>.metadata.mapped</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of mapped bytes in arena chunk headers, which |
| track the states of the non-metadata pages.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.metadata.allocated"> |
| <term> |
| <mallctl>stats.arenas.<i>.metadata.allocated</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of bytes dedicated to internal allocations. |
| Internal allocations differ from application-originated allocations in |
| that they are for internal use, and that they are omitted from heap |
| profiles. This statistic is reported separately from <link |
| linkend="stats.metadata"><mallctl>stats.metadata</mallctl></link> and |
| <link |
| linkend="stats.arenas.i.metadata.mapped"><mallctl>stats.arenas.<i>.metadata.mapped</mallctl></link> |
| because it overlaps with e.g. the <link |
| linkend="stats.allocated"><mallctl>stats.allocated</mallctl></link> and |
| <link linkend="stats.active"><mallctl>stats.active</mallctl></link> |
| statistics, whereas the other metadata statistics do |
| not.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.npurge"> |
| <term> |
| <mallctl>stats.arenas.<i>.npurge</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of dirty page purge sweeps performed. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.nmadvise"> |
| <term> |
| <mallctl>stats.arenas.<i>.nmadvise</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of <function>madvise<parameter>...</parameter> |
| <parameter><constant>MADV_DONTNEED</constant></parameter></function> or |
| similar calls made to purge dirty pages.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.purged"> |
| <term> |
| <mallctl>stats.arenas.<i>.purged</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of pages purged.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.small.allocated"> |
| <term> |
| <mallctl>stats.arenas.<i>.small.allocated</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of bytes currently allocated by small objects. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.small.nmalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.small.nmalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocation requests served by |
| small bins.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.small.ndalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.small.ndalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of small objects returned to bins. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.small.nrequests"> |
| <term> |
| <mallctl>stats.arenas.<i>.small.nrequests</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of small allocation requests. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.large.allocated"> |
| <term> |
| <mallctl>stats.arenas.<i>.large.allocated</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of bytes currently allocated by large objects. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.large.nmalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.large.nmalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of large allocation requests served |
| directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.large.ndalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.large.ndalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of large deallocation requests served |
| directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.large.nrequests"> |
| <term> |
| <mallctl>stats.arenas.<i>.large.nrequests</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of large allocation requests. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.huge.allocated"> |
| <term> |
| <mallctl>stats.arenas.<i>.huge.allocated</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Number of bytes currently allocated by huge objects. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.huge.nmalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.huge.nmalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of huge allocation requests served |
| directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.huge.ndalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.huge.ndalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of huge deallocation requests served |
| directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.huge.nrequests"> |
| <term> |
| <mallctl>stats.arenas.<i>.huge.nrequests</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of huge allocation requests. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.nmalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.nmalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocations served by bin. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.ndalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.ndalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocations returned to bin. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.nrequests"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.nrequests</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocation |
| requests.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.curregs"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.curregs</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Current number of regions for this size |
| class.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.nfills"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.nfills</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option> <option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Cumulative number of tcache fills.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.nflushes"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.nflushes</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option> <option>--enable-tcache</option>] |
| </term> |
| <listitem><para>Cumulative number of tcache flushes.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.nruns"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.nruns</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of runs created.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.nreruns"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.nreruns</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of times the current run from which |
| to allocate changed.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.bins.j.curruns"> |
| <term> |
| <mallctl>stats.arenas.<i>.bins.<j>.curruns</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Current number of runs.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.lruns.j.nmalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.lruns.<j>.nmalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocation requests for this size |
| class served directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.lruns.j.ndalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.lruns.<j>.ndalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of deallocation requests for this |
| size class served directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.lruns.j.nrequests"> |
| <term> |
| <mallctl>stats.arenas.<i>.lruns.<j>.nrequests</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocation requests for this size |
| class.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.lruns.j.curruns"> |
| <term> |
| <mallctl>stats.arenas.<i>.lruns.<j>.curruns</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Current number of runs for this size class. |
| </para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.hchunks.j.nmalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.hchunks.<j>.nmalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocation requests for this size |
| class served directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.hchunks.j.ndalloc"> |
| <term> |
| <mallctl>stats.arenas.<i>.hchunks.<j>.ndalloc</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of deallocation requests for this |
| size class served directly by the arena.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.hchunks.j.nrequests"> |
| <term> |
| <mallctl>stats.arenas.<i>.hchunks.<j>.nrequests</mallctl> |
| (<type>uint64_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Cumulative number of allocation requests for this size |
| class.</para></listitem> |
| </varlistentry> |
| |
| <varlistentry id="stats.arenas.i.hchunks.j.curhchunks"> |
| <term> |
| <mallctl>stats.arenas.<i>.hchunks.<j>.curhchunks</mallctl> |
| (<type>size_t</type>) |
| <literal>r-</literal> |
| [<option>--enable-stats</option>] |
| </term> |
| <listitem><para>Current number of huge allocations for this size class. |
| </para></listitem> |
| </varlistentry> |
| </variablelist> |
| </refsect1> |
| <refsect1 id="heap_profile_format"> |
| <title>HEAP PROFILE FORMAT</title> |
| <para>Although the heap profiling functionality was originally designed to |
| be compatible with the |
| <command>pprof</command> command that is developed as part of the <ulink |
| url="http://code.google.com/p/gperftools/">gperftools |
| package</ulink>, the addition of per thread heap profiling functionality |
| required a different heap profile format. The <command>jeprof</command> |
| command is derived from <command>pprof</command>, with enhancements to |
| support the heap profile format described here.</para> |
| |
| <para>In the following hypothetical heap profile, <constant>[...]</constant> |
| indicates elision for the sake of compactness. <programlisting><![CDATA[ |
| heap_v2/524288 |
| t*: 28106: 56637512 [0: 0] |
| [...] |
| t3: 352: 16777344 [0: 0] |
| [...] |
| t99: 17754: 29341640 [0: 0] |
| [...] |
| @ 0x5f86da8 0x5f5a1dc [...] 0x29e4d4e 0xa200316 0xabb2988 [...] |
| t*: 13: 6688 [0: 0] |
| t3: 12: 6496 [0: ] |
| t99: 1: 192 [0: 0] |
| [...] |
| |
| MAPPED_LIBRARIES: |
| [...]]]></programlisting> The following matches the above heap profile, but most |
| tokens are replaced with <constant><description></constant> to indicate |
| descriptions of the corresponding fields. <programlisting><![CDATA[ |
| <heap_profile_format_version>/<mean_sample_interval> |
| <aggregate>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] |
| [...] |
| <thread_3_aggregate>: <curobjs>: <curbytes>[<cumobjs>: <cumbytes>] |
| [...] |
| <thread_99_aggregate>: <curobjs>: <curbytes>[<cumobjs>: <cumbytes>] |
| [...] |
| @ <top_frame> <frame> [...] <frame> <frame> <frame> [...] |
| <backtrace_aggregate>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] |
| <backtrace_thread_3>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] |
| <backtrace_thread_99>: <curobjs>: <curbytes> [<cumobjs>: <cumbytes>] |
| [...] |
| |
| MAPPED_LIBRARIES: |
| </proc/<pid>/maps>]]></programlisting></para> |
| </refsect1> |
| |
| <refsect1 id="debugging_malloc_problems"> |
| <title>DEBUGGING MALLOC PROBLEMS</title> |
| <para>When debugging, it is a good idea to configure/build jemalloc with |
| the <option>--enable-debug</option> and <option>--enable-fill</option> |
| options, and recompile the program with suitable options and symbols for |
| debugger support. When so configured, jemalloc incorporates a wide variety |
| of run-time assertions that catch application errors such as double-free, |
| write-after-free, etc.</para> |
| |
| <para>Programs often accidentally depend on “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> |