You are viewing a plain text version of this content. The canonical link for it is here.
Posted to cvs@httpd.apache.org by dg...@hyperreal.org on 1997/10/24 11:39:19 UTC
cvs commit: apachen/htdocs/manual/misc perf-tuning.html
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>