Date: Thu, 22 Dec 2011 10:45:31 -0800 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: Attilio Rao <attilio@freebsd.org>, Andrey Chernov <ache@nagual.pp.ru>, George Mitchell <george+freebsd@m5p.com>, Doug Barton <dougb@freebsd.org>, freebsd-stable@freebsd.org Subject: Re: SCHED_ULE should not be the default Message-ID: <20111222184531.GA36084@troutmask.apl.washington.edu> In-Reply-To: <20111222103145.GA42457@onelab2.iet.unipi.it> 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>
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On Thu, Dec 22, 2011 at 11:31:45AM +0100, Luigi Rizzo wrote: > On Wed, Dec 21, 2011 at 04:52:50PM -0800, Steve Kargl wrote: > > > > I have placed several files at > > > > http://troutmask.apl.washington.edu/~kargl/freebsd > > > > dmesg.txt --> dmesg for ULE kernel > > summary --> A summary that includes top(1) output of all runs. > > sysctl.ule.txt --> sysctl -a for the ULE kernel > > ktr-ule-problem-kargl.out.gz I've replaced the original version of the ktr file with a new version. The old version was corrupt due to my failure to set 'sysctl debug.ktr.mask=0' prior to the dump. > One explanation for taking 1.5-2x times is that with ULE the > threads are not migrated properly, so you end up with idle cores > and ready threads not running (the other possible explanation > would be that there are migrations, but they are so frequent and > expensive that they completely trash the caches. But this seems > unlikely for this type of task). I've used schedgraph to look at the ktrdump output. A jpg is available at http://troutmask.apl.washington.edu/~kargl/freebsd/ktr.jpg This shows the ping-pong effect where here 3 processes appear to be using 2 cpus while the remaining 2 processes are pinned to their cpus. -- Steve
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