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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Ingo Molnar <mingo@elte.hu>
Subject: Re: Linux 2.6.23
Date: Fri, 12 Oct 2007 00:15:40 +1000
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Cc: Nicholas Miell <nmiell@comcast.net>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Friday 12 October 2007 15:46, Ingo Molnar wrote:
> * Nick Piggin <nickpiggin@yahoo.com.au> wrote:
> > ;) I think you snipped the important bit:
> >
> > "the peak is terrible but it has virtually no dropoff and performs
> > better under load than the default 2.6.21 scheduler." (verbatim)
>
> hm, i understood that peak remark to be in reference to FreeBSD's
> scheduler (which the FreeBSD guys are primarily interested in
> obviously), not v2.6.21 - but i could be wrong.

I think the Linux peak has always been roughly as good as their
best FreeBSD ones (eg. http://people.freebsd.org/~jeff/sysbench.png).
Obviously in that graph, Linux sucks because of the malloc/mmap_sem
issue. It also shows what he is calling the terrible CFS peak, I
guess.

In my own tests, after that was fixed, Linux's peak got even a bit
higher, so that's the benchmark for performance.


> In any case, there is indeed a regression with sysbench and a low number
> of threads, and it's being fixed. The peak got improved visibly in
> sched-devel:
>
>   http://people.redhat.com/mingo/misc/sysbench-sched-devel.jpg
>
> but there is still some peak regression left, i'm testing a patch for
> that.

OK good. Once that's fixed, we'll hopefully be competitive with
FreeBSD again in this test :)
-
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