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Date:      Fri, 17 Feb 2012 11:53:14 -0500
From:      Arnaud Lacombe <lacombar@gmail.com>
To:        Alexander Motin <mav@freebsd.org>
Cc:        freebsd-hackers@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:  <CACqU3MWEC4YYguPQF_d%2B_i_CwTc=86hG%2BPbxFgJQiUS-=AHiRw@mail.gmail.com>
In-Reply-To: <4F3E807A.60103@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>

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Hi,

On Fri, Feb 17, 2012 at 11:29 AM, Alexander Motin <mav@freebsd.org> wrote:
> 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. :)
>
is there a place where all the patches are available ? I intend to run
some tests on a 1x2x2 (atom D510), 1x4x1 (core-2 quad), and eventually
a 2x8x2 platforms, against r231573. Results should hopefully be
available by the end of the week-end/middle of next week[0].

 - Arnaud

[0]: the D510 will likely be testing a couple of Linux kernel over the
week-end, and a FreeBSD run takes about 2.5 days to complete.

>
> --
> Alexander Motin
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