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From Aaron Bannert <aa...@clove.org>
Subject Re: worker MPM Question
Date Sat, 17 Nov 2001 07:07:27 GMT
On Fri, Nov 16, 2001 at 10:22:36PM -0800, Ian Holsman wrote:
> 
> I've been doing some quick performance runs again, and have noticed (well.. 
> other people did before me) that the worker MPM tends to concentrate all 
> it's work to a few processes leaving
> others doing nothing.
> 
> Is this by design?

No it's not, but it may be an unfortunate side effect of the current
processing model and how solaris migrates LWPs to other CPUs. You're
probably running on that 6-CPU machine, and given the short-processing
times of the workers before they return to idle it is likely that
solaris (accurately) predicts that it would cost more to migrate to a
new CPU than to just keep it on the same one. How many child processes?
Threads/Process? Attempted req/sec, max that you can get? What is the
application (static page, SSI, other filters/proxy/etc)?

It's also possible that we're still having mutex contention problems,
so let me know if you're still seeing that. I have an account on nagoya
now that I'm going to play with (the 6-cpu monster up in Santa Clara
that runs jakarta.apache.org), so maybe something good will come of that.

I also posted the alternative model patch a while back. I doubt it still
applies cleanly, but it may be worth a try.

If you give me some more details about what kinds of bottlenecks you're
seeing (limit on req/sec, hitting a max number of context switching,
not network/IO limits -- which we had a hard time factoring out before,
IIRC) I might be able to pin down something in the code that's causing it.

-aaron

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