Date: Thu, 13 Jun 2013 14:01:27 +0200 From: Remy Nonnenmacher <remy.nonnenmacher@activnetworks.com> To: Mark Felder <feld@feld.me> Cc: "freebsd-performance@freebsd.org" <freebsd-performance@freebsd.org> Subject: Re: Scaling and performance issues with FreeBSD 9 (& 10) on 4 socket systems Message-ID: <51B9B497.70800@activnetworks.com> In-Reply-To: <op.wyl7oryz34t2sn@markf.office.supranet.net> References: <20130612225849.GA2858@dragon.NUXI.org> <op.wyl7oryz34t2sn@markf.office.supranet.net>
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On 06/13/13 13:32, Mark Felder wrote: > On Wed, 12 Jun 2013 17:58:49 -0500, David O'Brien <obrien@freebsd.org> > wrote: > >> We found FreeBSD 8.4 to perform better than FreeBSD 9.1, and Linux >> considerably better than both on the same machine. > > http://svnweb.freebsd.org/base?view=revision&revision=241246 > > The above link is likely why 8.4 is better than 9.1 on the same machine. > >> We've tried various things and haven't been able to explain why FreeBSD >> isn't scaling on the new hardware. Nor why it performs so much worse >> than FreeBSD on the older "M2" machines. > > The CPUs between those machines are quite different. I'm sure we're > looking at different cache sizes, different behavior for the > hyperthreading, etc. I'm sure others would be greatly interested in you > providing the same benchmark results for a recent snapshot of HEAD as well. > _______________________________________________ > freebsd-performance@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-performance > To unsubscribe, send any mail to > "freebsd-performance-unsubscribe@freebsd.org" We had same problem on 4x12 cores (AMD) machines. After investigating using hwpmc, it appears that performance was killed by a scheduler function trying to find "least used cpu" that unfortunately works on contended structures (ie: lots a cores are fighting to get works). A solution was found by using artificially long queue of stuck process (steal_thresh bumped to over 8) and by cpu affinity crafting. Was a year ago and from my memory. I guess you may give a try to see if it helps. Disregard is a scheduler specialist contradicts. Thanks.
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