Date: Fri, 23 Dec 2011 11:11:46 -0800 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-stable@freebsd.org, Andriy Gapon <avg@freebsd.org> Subject: Re: SCHED_ULE should not be the default Message-ID: <20111223191146.GA56232@troutmask.apl.washington.edu> In-Reply-To: <CAJ-VmokeyDrKb-yQkzTm8tnOYcRm603hz%2B6nen10F3zFQVmCEQ@mail.gmail.com> References: <4EE1EAFE.3070408@m5p.com> <CAJ-FndBSOS3hKYqmPnVkoMhPmowBBqy9-%2BeJJEMTdoVjdMTEdw@mail.gmail.com> <20111215215554.GA87606@troutmask.apl.washington.edu> <CAJ-FndD0vFWUnRPxz6CTR5JBaEaY3gh9y7-Dy6Gds69_aRgfpg@mail.gmail.com> <20111222005250.GA23115@troutmask.apl.washington.edu> <20111222103145.GA42457@onelab2.iet.unipi.it> <20111222184531.GA36084@troutmask.apl.washington.edu> <4EF37E7B.4020505@FreeBSD.org> <20111222194740.GA36796@troutmask.apl.washington.edu> <CAJ-VmokeyDrKb-yQkzTm8tnOYcRm603hz%2B6nen10F3zFQVmCEQ@mail.gmail.com>
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On Thu, Dec 22, 2011 at 04:23:29PM -0800, Adrian Chadd wrote: > On 22 December 2011 11:47, Steve Kargl <sgk@troutmask.apl.washington.edu> wrote: > > > There is the additional observation in one of my 2008 > > emails (URLs have been posted) that if you have N+1 > > cpu-bound jobs with, say, job0 and job1 ping-ponging > > on cpu0 (due to ULE's cpu-affinity feature) and if I > > kill job2 running on cpu1, then neither job0 nor job1 > > will migrate to cpu1. ?So, one now has N cpu-bound > > jobs running on N-1 cpus. > > .. and this sounds like a pretty serious regression. Have you ever > filed a PR for it? > Ah, so goods news! I cannot reproduce this problem that I saw 3+ years ago on the 4-cpu node, which is currently running a ULE kernel. When I killed the (N+1)th job, the N remaining jobs are spread across the N cpus. One difference between the 2008 tests and today tests is the number of available cpus. In 2008, I ran the tests on a node with 8 cpus, while today's test used only a node with only 4 cpus. If this behavior is a scaling issue, I can't currently test it. But, today's tests are certainly encouraging. -- Steve
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