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From Dirk-Willem van Gulik <>
Subject Re: OSDLab projectL Accept() locking on large (6+ CPU) boxes
Date Tue, 24 Jul 2001 23:38:46 GMT

On Tue, 24 Jul 2001, Bill Stoddard wrote:

> Some folks in the Websphere performance team did some benchmarking on
> machines from Sun all the way up to 8-ways. Victor was feeding them
> Apache builds to play with. We tried the following accept locks:
> fcntl, native Solaris, sysv, pthread.  fcnlt was slowest on all
> machines with 4 CPUs or less.  fcntl was the fastest on the 8 way
> machine.

This matches what we found.

> sysv, pthread and native Solaris locks all appeared to actually
> degrade performance as CPUs were added and in the same way which leads
> me to believe that sysv, pthread and native Solaris locks are all the
> same implementation under the covers.

Same here; we looked under the covers with sar - and they certainly share
the same mechanism.

> We did the same tests with AIX. I am not advertising here, but Apache
> on AIX using pthread mutexes kicks Solaris butt big time on the 8 way
> (and above) machines. Apache performance on AIX 8 way machines is MUCH
> better than Solaris.

Though based on operational experience I certainly have found the same;
big fat AIX do really, really, really well -and behave incredibly nice and
robust as you add processor after processor..... I am not sure that:

> Each OS has strengths and weaknesses and it appears that Solaris is
> very weak in cross process locking on n-way machines. So I would say
> that the problem is Sun specfic. Haven't done similar measurements
> with Linux.

is so solaris specific. I think there is also something fundamental in the
way we do things in apache. But time in the lab will tell :-)


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