Date: Mon, 26 Feb 2007 14:52:05 -0500 From: Kris Kennaway <kris@obsecurity.org> To: Peter Jeremy <peterjeremy@optushome.com.au> Cc: smp@freebsd.org, hackers@freebsd.org, current@freebsd.org, Kris Kennaway <kris@obsecurity.org> Subject: Re: Progress on scaling of FreeBSD on 8 CPU systems Message-ID: <20070226195204.GA14353@xor.obsecurity.org> In-Reply-To: <20070226080837.GB844@turion.vk2pj.dyndns.org> References: <20070224213111.GB41434@xor.obsecurity.org> <20070226080837.GB844@turion.vk2pj.dyndns.org>
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On Mon, Feb 26, 2007 at 07:08:37PM +1100, Peter Jeremy wrote: > On 2007-Feb-24 16:31:11 -0500, Kris Kennaway <kris@obsecurity.org> wrote: > >We have recently made significant progress on optimizing for MySQL > >running on an 8-core amd64 system. The graph of results may be found > >here: > > > > http://www.freebsd.org/~kris/scaling/scaling.png > > Those results look wonderful. Have you tried increasing the number of > threads to see if there's any nasty knee further to the right? Also, > is there any chance of repeating this testing on one of the big Suns > (or a T2000) to see how this scales to lots of cores? I didnt try at much higher loads yet, that will be interesting to explore. Currently on the Sun T2000 (32 hardware threads = virtual CPUs) we don't have good scaling (it's hard even to saturate all CPUs for kernel workloads): the current thinking is that this is largely because of contention on the global scheduler lock. Even when idle there is a lot of contention on the sched_lock coming from e.g. all 32 CPUs running statclock at once HZ=1000 times a second and fighting for the sched_lock. Fixing this is something Jeff and Attilio are working on (Kip Macy also did a lot of exploratory work last year), so we hope to make further progress over the coming weeks. Kris
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