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Subject Re: 2.0.48 worker mpm on RH3 NPTL results
Date Mon, 12 Jan 2004 16:45:50 GMT
Jean-Jacques Clar wrote:

> Attached are 2.0.48 numbers on RH AS 2.1 and 3.0.
> Apache is build with worker MPM and default options on both versions.

Thanks for posting these measurements.  I was happy to see that performance 
stays pretty flat as the system got overloaded.  The AS 3.0 8 CPU curve sags a 
little but it's not too bad.

What did you use for ThreadsPerChild?  The default?  It's 25.  The reason I ask 
is I did some scalability measurements maybe a year ago and saw a lot of CPU 
usage in linuxthreads with a high number (maybe 1000) for ThreadsPerChild.  It 
was in some pthread mutex unlock function, doing a serial search for the highest 
priority thread to wake up.  This is pointless in our case because all the 
worker threads are the same priority.  I'm hoping that this problem is fixed in 
the new pthread library, but haven't verified it.

> C:
> Apache is servicing more requests per sec on 2.1 on 1 and 2 CPUs, 3.0 is 
> picking up the slack between 2 and 4 CPUs.
> Prefork still serving static requests faster than worker (6300 req/sec 
> on RH 2.1 on 8 CPUs).

I'm very curious to know why prefork is beating worker.  Could you get a profile 
of the CPU usage for both cases?  I've had good luck with oprofile.  I had a 
little trouble compiling its kernel module on RH AS 2.1 due to 2.5 kernel 
features that RedHat backported, but you can edit oprofile's module/compat.h to 
get around that.


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