dgaudet 97/10/24 02:39:19
Modified: htdocs/manual/misc perf-tuning.html Log: document MMAP_SEGMENT_SIZE Revision Changes Path 1.2 +16 -9 apachen/htdocs/manual/misc/perf-tuning.html Index: perf-tuning.html =================================================================== RCS file: /export/home/cvs/apachen/htdocs/manual/misc/perf-tuning.html,v retrieving revision 1.1 retrieving revision 1.2 diff -u -r1.1 -r1.2 --- perf-tuning.html 1997/09/30 23:24:30 1.1 +++ perf-tuning.html 1997/10/24 09:39:17 1.2 @@ -690,16 +690,23 @@ On some architectures it's slower to <code>mmap</code> small files than it is to simply <code>read</code> them. The define -<code>MMAP_THRESHOLD</code> can be set to the minimum size required before -using <code>mmap</code>. By default it's set to 0 (except on SunOS4 -where experimentation has shown 8192 to be a better value). Using a -tool such as -<a href="http://reality.sgi.com/lm_engr/lmbench/lmbench.html">lmbench</a> -you can determine the optimal setting for your -environment. It may even be the case that <code>mmap</code> isn't used -on your architecture, if so then defining <code>USE_MMAP_FILES</code> -might work (if it works then report back to us). +<code>MMAP_THRESHOLD</code> can be set to the minimum +size required before using <code>mmap</code>. By default +it's set to 0 (except on SunOS4 where experimentation has +shown 8192 to be a better value). Using a tool such as <a +href="http://reality.sgi.com/lm_engr/lmbench/lmbench.html">lmbench</a> you +can determine the optimal setting for your environment. + +<p>You may also wish to experiment with <code>MMAP_SEGMENT_SIZE</code> +(default 32768) which determines the maximum number of bytes that +will be written at a time from mmap()d files. Apache only resets the +client's <code>Timeout</code> in between write()s. So setting this +large may lock out low bandwidth clients unless you also increase the +<code>Timeout</code>. +<p>It may even be the case that <code>mmap</code> isn't +used on your architecture, if so then defining <code>USE_MMAP_FILES</code> +might work (if it works then report back to us). <p>Apache does its best to avoid copying bytes around in memory. The first write of any request typically is turned into a <code>writev</code>