On 2011-05-31 14.45, Artur Grabowski wrote:
> The load average is a decaying average of the number of processes in
> the runnable state or currently running on a cpu or in the process of
> being forked or that have spent less than a second in a sleep state
> with sleep priority lower than PZERO, which includes waiting for
> memory resources, disk I/O, filesystem locks and a bunch of other
> things. You could say it's a very vague estimate of how much work the
> cpu might need to be doing soon, maybe. Or it could be completely
> wrong because of sampling bias. It's not very important so it's not
> really critical for the system to do a good job guessing this number,
> so the system doesn't really try too hard.
>
> This number may tell you something useful, or it might be totally
> misleading. Or both.
One thing that often bites me in the butt is that cron relies on the
load average to decide if it should let batch(1) jobs run or not.
The default is if cron sees a loadavg > 1.5 it keeps the batch job
enqueued until it drops below that value. As I often see much, much
higher loads on my systems, invariably I find myself wondering why my
batch jobs never finish, just to discover that they have yet to run.
*duh*
So whenever I remember to, on every new system I set up I configure a
different load threshold value for cron. But I tend to forget, so...
:-)
I have no really good suggestion for how else cron should handle this,
otherwise I would have submitted a patch ages ago...
Regards,
/Benny
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