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Re: (ot) What is load average?



On Mon, May 22, 2000 at 09:50:03PM -0400, Jonathan Lupa wrote:
> This is certainly offtopic, but what does the following mean?
> 
> Rankor:/$ cat /proc/loadavg
> 2.19 1.27 0.79 1/54 1667
> 
> I know that the first three are 5, 10, and 15 minute averages, but I'm
> not sure what "load" really is.

Number of processes in the run queue, averaged over time.  Often
confused with CPU utilization, which it is not.  At load >= 1, CPU
utilization is nominally 100% -- for a 1 CPU box.  For an SMP box, eg:
the 14-way Sun E10K I worked on a while back, a load average of 7 was
50% utilization.

The fourth value is running processes vs. total threads, and the fifth
value is the most recently assigned process ID.

You can find this information by grubbing about in
/usr/src/linux/fs/proc/array.c

> I'm curious what those numbers represent and what reasonable values
> are for them... Are the CPU, memory, or IO related..? A pointer to a
> doc would be cool if available...

Reasonable depends on your needs.  A system with a load average some
higher than the number of CPUs present will probably benefit from
additional CPU(s).  Sustained loads more than, say, 4-5 times CPUs
indicated a pretty saturated system.

  7:19pm  up 33 days, 17:29, 17 users,  load average: 2.00, 2.03, 2.14


-- 
Karsten M. Self <kmself@ix.netcom.com>         http://www.netcom.com/~kmself
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