Yenya's World

Tue, 14 Feb 2006

Apache2 CPU time

Yesterday we had a huge load peak at IS MU (seminars registration or something like that). It turned out to be that we had few inoptimalities in our cluster configuration. I have spent the last night benchmarking and tweaking Apache.

Apache2 CPU time graph

Probably the most interesting change, even visible on a MRTG graph is that I have changed the SSL session cache from DBM to the shared memory, which on our dual-core systems seem to help a bit. In the above graph the change has been made at 13:00 (the last hour on the right side). It is quite clear that both the system time (orange area) and the user time (red line) are lower in the last hour. I made the following change in httpd.conf:

-SSLSessionCache dbm:log-mu/ssl_gcache_data
-SSLMutex file:log-mu/ssl_mutex
+SSLSessionCache shm:log-mu/ssl_gcache_data(512000)
+SSLMutex sysvsem

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