Date: Thu, 5 Apr 2012 14:12:13 -0400 From: Arnaud Lacombe <lacombar@gmail.com> To: Alexander Motin <mav@freebsd.org> Cc: freebsd-hackers@freebsd.org, Florian Smeets <flo@freebsd.org>, Jeff Roberson <jroberson@jroberson.net>, Andriy Gapon <avg@freebsd.org>, FreeBSD current <freebsd-current@freebsd.org> Subject: Re: [RFT][patch] Scheduling for HTT and not only Message-ID: <CACqU3MWZj503xN_-wr6s%2BXOB7JGhhBgaWW0gOX60KJvU3Y=Rig@mail.gmail.com> In-Reply-To: <4F3E8858.4000001@FreeBSD.org> 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> <4F3E807A.60103@FreeBSD.org> <CACqU3MWEC4YYguPQF_d%2B_i_CwTc=86hG%2BPbxFgJQiUS-=AHiRw@mail.gmail.com> <4F3E8858.4000001@FreeBSD.org>
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Hi, [Sorry for the delay, I got a bit sidetrack'ed...] 2012/2/17 Alexander Motin <mav@freebsd.org>: > On 17.02.2012 18:53, Arnaud Lacombe wrote: >> >> On Fri, Feb 17, 2012 at 11:29 AM, Alexander Motin<mav@freebsd.org> =A0wr= ote: >>> >>> 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 numbe= r >>> 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 neede= d >>> 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 (excep= t >>> some debugging KTRs) in about ten days. So now it's a good time for >>> reviews >>> and testing. :) >>> >> is there a place where all the patches are available ? > > > All my scheduler patches are cumulative, so all you need is only the last > mentioned here sched.htt40.patch. > You may want to have a look to the result I collected in the `runs/freebsd-experiments' branch of: https://github.com/lacombar/hackbench/ and compare them with vanilla FreeBSD 9.0 and -CURRENT results available in `runs/freebsd'. On the dual package platform, your patch is not a definite win. > But in some cases, especially for multi-socket systems, to let it show it= s > best, you may want to apply additional patch from avg@ to better detect C= PU > topology: > https://gitorious.org/~avg/freebsd/avgbsd/commit/6bca4a2e4854ea3fc275946a= 023db65c483cb9dd > test I conducted specifically for this patch did not showed much improvemen= t... - Arnaud
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