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Chapter 12. Server Operating System > Unix OS Monitoring Tools

12.8. Unix OS Monitoring Tools

Most versions of Unix collect performance metrics once per second from the kernel, so most Unix performance monitoring facilities do not allow a sample rate of greater than once per second. You wouldn't want to do much more monitoring of general statistics anyway, because the measurement itself would significantly add to the load. Read the manpage on each of these for more detailed information. Here are the major monitoring tools and some example output on a heavily loaded web server.

12.8.1. ps

The most basic tool to let you know what's going on is ps, which displays all your processes along with information on CPU and memory usage. The options to ps vary a great deal with OS, so you need to read the ps manpage on your system for more details. An important point to remember is that Berkeley-style priorities are opposite from SVR4 priorities. In SVR4, higher numbers mean higher priority. You can display SVR4 priority with the -c option. Here's a listing sorted by priority and edited a bit for clarity:


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