Followup to: <3A0C929B.EE6F7137@linux.com>
By author: David Ford <david@linux.com>
In newsgroup: linux.dev.kernel
>
> - Requires high load average allowance
> Incorrect. Same machine barely spiked a tenth of a point for this load and dropped
> back to .05. Only time I adjusted the configured load average allowance was back in my
> naive days and we got hit with 80,000 in the queue at one time from multiple spammers.
> Part of this test's load came from numerous things running and the mail sending required
> spinup of the drive which blocked.
>
Well, I think it does, but not because it itself is generating much of
a load. I had it block traffic on my desktop machine while doing a
kernel compile; I run with high parallelism and the load occationally
spikes in the high 20's. However, the machine is perfectly
responsive, and so I was a little taken back by this.
The way Linux computes the load average really does call for higher
limits than what BSD does. This isn't inherently a "good" or "bad"
thing -- it's just a fact of life. That being said, it probably would
be useful if the Sendmail people would provide higher default limits
in cf/ostype/linux.m4 than for other systems.
The one thing about load average that is making it a bit hard to deal
with is that workloads on modern machines tend to vary a little too
quickly for the standard load average time constants to deal well with
them. It's probably fine for throttling down a machine that is
getting killed with requests, but not really enough to keep, say,
parallel make without a limit ("make -j" as opposed to "make -j5")
from forking the machine to the point where the make itself fails
before knowing what just hit it.
-hpa
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This archive was generated by hypermail 2b29 : Wed Nov 15 2000 - 21:00:18 EST