Date: Wed, 24 Oct 2007 11:49:54 -0400 From: Nick Evans <nevans@talkpoint.com> To: josh.carroll@gmail.com Cc: remy.nonnenmacher@activnetworks.com, Kris Kennaway <kris@freebsd.org>, freebsd-performance@freebsd.org, Bruce Evans <brde@optusnet.com.au> Subject: Re: ULE vs. 4BSD in RELENG_7 Message-ID: <20071024114954.5ea1b37b@pleiades.nextvenue.com> In-Reply-To: <8cb6106e0710240839h1a59f9f9y919e6b297c3efb8e@mail.gmail.com> References: <8cb6106e0710230902x4edf2c8eu2d912d5de1f5d4a2@mail.gmail.com> <471E343C.2040509@FreeBSD.org> <20071024171915.E84143@delplex.bde.org> <8cb6106e0710240639r20e03ce9w81ed3354338b7395@mail.gmail.com> <20071024113434.326c3749@pleiades.nextvenue.com> <8cb6106e0710240839h1a59f9f9y919e6b297c3efb8e@mail.gmail.com>
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On Wed, 24 Oct 2007 11:39:52 -0400 "Josh Carroll" <josh.carroll@gmail.com> wrote: > > kern.sched.steal_thresh is/was one of the more effective tuning sysctls. > > rev 1.205 of sched_ule had a change that was supposed to automatically > > adjust it based on the number of cores. Is this the same 8 core system as > > the other thread? In that case the commit dictates steal_thresh should be > > set to 3. Give that a try. > > This is a quad core (single cpu) system. Do these values look proper then? > > kern.sched.steal_thresh: 2 > kern.sched.steal_idle: 1 > kern.sched.steal_htt: 1 > > Thanks, > Josh Yes, that's the proper default. You could try setting steal_thresh to 1. I noticed a problem with building ports on an 8 core Xeon system while 8 distributed.net crunchers were running. The port build would proceed incredibly slowly, steal_thresh=1 helped a little bit. It might not make up the 5% gap you're seeing though. During early ULE2/3 testing the other variables Jeff recommended trying were sched.pick_pri (which I never saw effect from), sched_tryself and sched.balance. They're all bools IIRC. Since this workload is a bit different from any of mine it would be worthwhile to try those variables. Nick
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