Date: Fri, 17 Feb 2012 18:29:46 +0200 From: Alexander Motin <mav@FreeBSD.org> To: Jeff Roberson <jroberson@jroberson.net> Cc: freebsd-hackers@FreeBSD.org, Florian Smeets <flo@FreeBSD.org>, Andriy Gapon <avg@FreeBSD.org>, FreeBSD current <freebsd-current@freebsd.org> Subject: Re: [RFT][patch] Scheduling for HTT and not only Message-ID: <4F3E807A.60103@FreeBSD.org> In-Reply-To: <alpine.BSF.2.00.1202150949480.2020@desktop> References: <4F2F7B7F.40508@FreeBSD.org> <4F366E8F.9060207@FreeBSD.org> <4F367965.6000602@FreeBSD.org> <4F396B24.5090602@FreeBSD.org> <alpine.BSF.2.00.1202131012270.2020@desktop> <4F3978BC.6090608@FreeBSD.org> <alpine.BSF.2.00.1202131108460.2020@desktop> <4F3990EA.1080002@FreeBSD.org> <4F3C0BB9.6050101@FreeBSD.org> <alpine.BSF.2.00.1202150949480.2020@desktop>
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On 02/15/12 21:54, Jeff Roberson wrote: > On Wed, 15 Feb 2012, Alexander Motin wrote: >> I've decided to stop those cache black magic practices and focus on >> things that really exist in this world -- SMT and CPU load. I've >> dropped most of cache related things from the patch and made the rest >> of things more strict and predictable: >> http://people.freebsd.org/~mav/sched.htt34.patch > > This looks great. I think there is value in considering the other > approach further but I would like to do this part first. It would be > nice to also add priority as a greater influence in the load balancing > as well. I haven't got good idea yet about balancing priorities, but I've rewritten balancer itself. As soon as sched_lowest() / sched_highest() are more intelligent now, they allowed to remove topology traversing from the balancer itself. That should fix double-swapping problem, allow to keep some affinity while moving threads and make balancing more fair. I did number of tests running 4, 8, 9 and 16 CPU-bound threads on 8 CPUs. With 4, 8 and 16 threads everything is stationary as it should. With 9 threads I see regular and random load move between all 8 CPUs. Measurements on 5 minutes run show deviation of only about 5 seconds. It is the same deviation as I see caused by only scheduling of 16 threads on 8 cores without any balancing needed at all. So I believe this code works as it should. Here is the patch: http://people.freebsd.org/~mav/sched.htt40.patch I plan this to be a final patch of this series (more to come :)) and if there will be no problems or objections, I am going to commit it (except some debugging KTRs) in about ten days. So now it's a good time for reviews and testing. :) -- Alexander Motin
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