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Web Performance Tuning by Patrick Killelea

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Tuning Your System

Things to Watch

Did you reserve enough swap space? You should have at least as much swap as you have main memory. If you have little main memory, then you should have double that amount as swap. Do not be fooled by the result of the vmstat command—read the manpage and realize that the small value for free memory shown there is (usually) correct.

With Solaris there seems to exist a difference between virtually generated processes and real processes. The latter are extremely dependent on the amount of virtual memory. To test the number of both kinds of processes, try a small program of mine, testpid.c, available from my web page. Start it at the console without starting the X Window System, and not as root. The first value is the hard limit of processes, and the second value the number of processes you can really create given your virtual memory configuration. Tweaking your ulimit values may or may not help.

General Entries in the File /etc/system

The file /etc/system contains various very important configurable parameters for your system. You can use these tunings to give a heavily loaded system more resources of a certain kind. Unfortunately, these changes won’t take effect until the next reboot.

In Sun Performance and Tuning, Adrian Cockroft warns against transporting an /etc/system from one system onto another, or even worse, onto another hardware platform:

Clean out your /etc/system when you upgrade.

The most frequent changes are limited to the number of file descriptors, ...

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