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<h3 class="section">10.20 Caching Data of Remote Targets</h3>

<p><a name="index-caching-data-of-remote-targets-653"></a>
<span class="sc">gdb</span> caches data exchanged between the debugger and a
remote target (see <a href="Remote-Debugging.html#Remote-Debugging">Remote Debugging</a>).  Such caching generally improves
performance, because it reduces the overhead of the remote protocol by
bundling memory reads and writes into large chunks.  Unfortunately, simply
caching everything would lead to incorrect results, since <span class="sc">gdb</span>
does not necessarily know anything about volatile values, memory-mapped I/O
addresses, etc.  Furthermore, in non-stop mode (see <a href="Non_002dStop-Mode.html#Non_002dStop-Mode">Non-Stop Mode</a>)
memory can be changed <em>while</em> a gdb command is executing. 
Therefore, by default, <span class="sc">gdb</span> only caches data
known to be on the stack<a rel="footnote" href="#fn-1" name="fnd-1"><sup>1</sup></a>. 
Other regions of memory can be explicitly marked as
cacheable; see see <a href="Memory-Region-Attributes.html#Memory-Region-Attributes">Memory Region Attributes</a>.

     
<a name="index-set-remotecache-654"></a>
<dl><dt><code>set remotecache on</code><dt><code>set remotecache off</code><dd>This option no longer does anything; it exists for compatibility
with old scripts.

     <p><a name="index-show-remotecache-655"></a><br><dt><code>show remotecache</code><dd>Show the current state of the obsolete remotecache flag.

     <p><a name="index-set-stack_002dcache-656"></a><br><dt><code>set stack-cache on</code><dt><code>set stack-cache off</code><dd>Enable or disable caching of stack accesses.  When <code>ON</code>, use
caching.  By default, this option is <code>ON</code>.

     <p><a name="index-show-stack_002dcache-657"></a><br><dt><code>show stack-cache</code><dd>Show the current state of data caching for memory accesses.

     <p><a name="index-info-dcache-658"></a><br><dt><code>info dcache </code><span class="roman">[</span><code>line</code><span class="roman">]</span><dd>Print the information about the data cache performance.  The
information displayed includes the dcache width and depth, and for
each cache line, its number, address, and how many times it was
referenced.  This command is useful for debugging the data cache
operation.

     <p>If a line number is specified, the contents of that line will be
printed in hex. 
</dl>

   <div class="footnote">
<hr>
<h4>Footnotes</h4><p class="footnote"><small>[<a name="fn-1" href="#fnd-1">1</a>]</small> In non-stop mode, it is moderately
rare for a running thread to modify the stack of a stopped thread
in a way that would interfere with a backtrace, and caching of
stack reads provides a significant speed up of remote backtraces.</p>

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