Subject: Re: x264 benchmarks BFS vs CFS
From: Kasper Sandberg <lkml@metanurb.dk>
To: Jason Garrett-Glaser <darkshikari@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Mike Galbraith <efault@gmx.de>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       LKML Mailinglist <linux-kernel@vger.kernel.org>,
       Linus Torvalds <torvalds@linux-foundation.org>
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Date: Fri, 18 Dec 2009 11:56:46 +0100
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On Thu, 2009-12-17 at 17:18 -0800, Jason Garrett-Glaser wrote:
> On Thu, Dec 17, 2009 at 3:00 AM, Kasper Sandberg <lkml@metanurb.dk> wrote:
> > On Thu, 2009-12-17 at 11:53 +0100, Ingo Molnar wrote:
> >> * Jason Garrett-Glaser <darkshikari@gmail.com> wrote:
> >>
> >> > On Thu, Dec 17, 2009 at 1:33 AM, Kasper Sandberg <lkml@metanurb.dk> wrote:
> >> > > well well :) nothing quite speaks out like graphs..
> >> > >
> >> > > http://doom10.org/index.php?topic=78.0
> >> > >
> >> > >
> >> > >
> >> > > regards,
> >> > > Kasper Sandberg
> >> >
> >> > Yeah, I sent this to Mike a bit ago.  Seems that .32 has basically tied
> >> > it--and given the strict thread-ordering expectations of x264, you basically
> >> > can't expect it to do any better, though I'm curious what's responsible for
> >> > the gap in "veryslow", even with SCHED_BATCH enabled.
> >> >
> >> > The most odd case is that of "ultrafast", in which CFS immediately ties BFS
> >> > when we enable SCHED_BATCH.  We're doing some further testing to see exactly
> >
> > Thats kinda besides the point.
> >
> > all these tunables and weirdness is _NEVER_ going to work for people.
> 
> Can't individually applications request SCHED_BATCH?  Our plan was to
> have x264 simply detect if it was necessary (once we figure out what
> encoding settings result in the large gap situation) and automatically
> enable it for the current application.
that is an insane solution, especially considering better schedulers
outperform cfs SCHED_BATCH without doing ANYTHING special.

Do you not see what is happening here? it is simply grotesk
> 
> Jason

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