Date: Mon, 12 Dec 2011 16:32:21 +0100 From: Gary Jennejohn <gljennjohn@googlemail.com> To: Vincent Hoffman <vince@unsane.co.uk> Cc: "O. Hartmann" <ohartman@mail.zedat.fu-berlin.de>, Current FreeBSD <freebsd-current@freebsd.org>, freebsd-stable@freebsd.org, freebsd-performance@freebsd.org Subject: Re: SCHED_ULE should not be the default Message-ID: <20111212163221.33d0b8a2@ernst.jennejohn.org> In-Reply-To: <4EE619FC.4000601@unsane.co.uk> References: <4EE1EAFE.3070408@m5p.com> <4EE22421.9060707@gmail.com> <4EE6060D.5060201@mail.zedat.fu-berlin.de> <4EE619FC.4000601@unsane.co.uk>
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On Mon, 12 Dec 2011 15:13:00 +0000 Vincent Hoffman <vince@unsane.co.uk> wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 12/12/2011 13:47, O. Hartmann wrote: > > > >> Not fully right, boinc defaults to run on idprio 31 so this isn't an > >> issue. And yes, there are cases where SCHED_ULE shows much better > >> performance then SCHED_4BSD. [...] > > > > Do we have any proof at hand for such cases where SCHED_ULE performs > > much better than SCHED_4BSD? Whenever the subject comes up, it is > > mentioned, that SCHED_ULE has better performance on boxes with a ncpu > > > 2. But in the end I see here contradictionary statements. People > > complain about poor performance (especially in scientific environments), > > and other give contra not being the case. > It all a little old now but some if the stuff in > http://people.freebsd.org/~kris/scaling/ > covers improvements that were seen. > > http://jeffr-tech.livejournal.com/5705.html > shows a little too, reading though Jeffs blog is worth it as it has some > interesting stuff on SHED_ULE. > > I thought there were some more benchmarks floating round but cant find > any with a quick google. > > > Vince > > > > > Within our department, we developed a highly scalable code for planetary > > science purposes on imagery. It utilizes present GPUs via OpenCL if > > present. Otherwise it grabs as many cores as it can. > > By the end of this year I'll get a new desktop box based on Intels new > > Sandy Bridge-E architecture with plenty of memory. If the colleague who > > developed the code is willing performing some benchmarks on the same > > hardware platform, we'll benchmark bot FreeBSD 9.0/10.0 and the most > > recent Suse. For FreeBSD I intent also to look for performance with both > > different schedulers available. > > These observations are not scientific, but I have a CPU from AMD with 6 cores (AMD Phenom(tm) II X6 1090T Processor). My simple test was ``make buildkernel'' while watching the core usage with gkrellm. With SCHED_4BSD all 6 cores are loaded to 97% during the build phase. I've never seen any value above 97% with gkrellm. With SCHED_ULE I never saw all 6 cores loaded this heavily. Usually 2 or more cores were at or below 90%. Not really that significant, but still a noticeable difference in apparent scheduling behavior. Whether the observed difference is due to some change in data from the kernel to gkrellm is beyond me. -- Gary Jennejohn
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