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130 lines
5.7 KiB
HTML
130 lines
5.7 KiB
HTML
4 years ago
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<title>mallinfo (The Red Hat newlib C Library)</title>
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<meta name="description" content="mallinfo (The Red Hat newlib C Library)">
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<meta name="keywords" content="mallinfo (The Red Hat newlib C Library)">
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<link href="Document-Index.html#Document-Index" rel="index" title="Document Index">
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<link href="Document-Index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Stdlib.html#Stdlib" rel="up" title="Stdlib">
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<link href="_005f_005fmalloc_005flock.html#g_t_005f_005fmalloc_005flock" rel="next" title="__malloc_lock">
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<body lang="en">
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<a name="mallinfo"></a>
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<div class="header">
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<p>
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Next: <a href="_005f_005fmalloc_005flock.html#g_t_005f_005fmalloc_005flock" accesskey="n" rel="next">__malloc_lock</a>, Previous: <a href="malloc.html#malloc" accesskey="p" rel="prev">malloc</a>, Up: <a href="Stdlib.html#Stdlib" accesskey="u" rel="up">Stdlib</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="mallinfo_002c-malloc_005fstats_002c-mallopt_002d_002d_002dmalloc-support"></a>
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<h3 class="section">2.25 <code>mallinfo</code>, <code>malloc_stats</code>, <code>mallopt</code>—malloc support</h3>
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<a name="index-mallinfo"></a>
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<a name="index-malloc_005fstats"></a>
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<a name="index-mallopt"></a>
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<a name="index-_005fmallinfo_005fr"></a>
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<a name="index-_005fmalloc_005fstats_005fr"></a>
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<a name="index-_005fmallopt_005fr"></a>
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<p><strong>Synopsis</strong>
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</p><div class="example">
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<pre class="example">#include <malloc.h>
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struct mallinfo mallinfo(void);
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void malloc_stats(void);
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int mallopt(int <var>parameter</var>, <var>value</var>);
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struct mallinfo _mallinfo_r(void *<var>reent</var>);
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void _malloc_stats_r(void *<var>reent</var>);
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int _mallopt_r(void *<var>reent</var>, int <var>parameter</var>, <var>value</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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<code>mallinfo</code> returns a structure describing the current state of
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memory allocation. The structure is defined in malloc.h. The
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following fields are defined: <code>arena</code> is the total amount of space
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in the heap; <code>ordblks</code> is the number of chunks which are not in use;
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<code>uordblks</code> is the total amount of space allocated by <code>malloc</code>;
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<code>fordblks</code> is the total amount of space not in use; <code>keepcost</code> is
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the size of the top most memory block.
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</p>
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<p><code>malloc_stats</code> print some statistics about memory allocation on
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standard error.
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</p>
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<p><code>mallopt</code> takes a parameter and a value. The parameters are defined
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in malloc.h, and may be one of the following: <code>M_TRIM_THRESHOLD</code>
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sets the maximum amount of unused space in the top most block before
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releasing it back to the system in <code>free</code> (the space is released by
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calling <code>_sbrk_r</code> with a negative argument); <code>M_TOP_PAD</code> is the
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amount of padding to allocate whenever <code>_sbrk_r</code> is called to
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allocate more space.
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</p>
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<p>The alternate functions <code>_mallinfo_r</code>, <code>_malloc_stats_r</code>, and
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<code>_mallopt_r</code> are reentrant versions. The extra argument <var>reent</var>
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is a pointer to a reentrancy structure.
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</p>
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<br>
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<p><strong>Returns</strong><br>
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<code>mallinfo</code> returns a mallinfo structure. The structure is defined
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in malloc.h.
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</p>
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<p><code>malloc_stats</code> does not return a result.
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</p>
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<p><code>mallopt</code> returns zero if the parameter could not be set, or
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non-zero if it could be set.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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<code>mallinfo</code> and <code>mallopt</code> are provided by SVR4, but <code>mallopt</code>
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takes different parameters on different systems. <code>malloc_stats</code> is
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not portable.
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</p>
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<br>
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<hr>
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<div class="header">
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<p>
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Next: <a href="_005f_005fmalloc_005flock.html#g_t_005f_005fmalloc_005flock" accesskey="n" rel="next">__malloc_lock</a>, Previous: <a href="malloc.html#malloc" accesskey="p" rel="prev">malloc</a>, Up: <a href="Stdlib.html#Stdlib" accesskey="u" rel="up">Stdlib</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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