Re: computing load averages

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Shragai, Yaron wrote:
Hello,
How are load averages computed for the top command and the /proc/loadavg
file?  Where do the numbers come from?

Thanks,
Yaron



cat /proc/loadavg

These are numbers internal to the kernel.

They are 5, 10 and 15 minute average values
of the number of processes that are in a "run" state at each sample.

You should consider your load in reference to the number of CPU's you have in a system. If you have 8 CPU's, then having a load of 7 isn't a problem. If the load is higher than the number of CPU's then you should look at your top's CPU stats, and look at iostat and vmstat and sar.

A box can have a high load for several different reasons (or combinations of those reasons). You may have a number of processes all running simultaneously and the CPU is just running as fast as possible (evidenced by less than 2% idle time shown in top for CPU usage).

You may have a number of processes that are in run states, but are waiting for data i/o (evidenced by having abundant CPU idle time, but still having a load higher than the number of CPU's).

Check vmstat for memory swap activity, i/o activity

-Ben.

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