linux-kernel - Re: x264 benchmarks BFS vs CFS

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Date:	Fri, 18 Dec 2009 03:05:34 -0800
From:	Jason Garrett-Glaser <darkshikari@...il.com>
To:	Kasper Sandberg <lkml@...anurb.dk>
Cc:	Mike Galbraith <efault@....de>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML Mailinglist <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: x264 benchmarks BFS vs CFS

On Fri, Dec 18, 2009 at 2:57 AM, Kasper Sandberg <lkml@...anurb.dk> wrote:
> On Fri, 2009-12-18 at 08:30 +0100, Mike Galbraith wrote:
>> On Fri, 2009-12-18 at 06:23 +0100, Ingo Molnar wrote:
>>
>> > Having said that, we generally try to make things perform well without apps
>> > having to switch themselves to SCHED_BATCH. Mike, do you think we can make
>> > x264 perform as well (or nearly as well) under SCHED_OTHER as under
>> > SCHED_BATCH?
>>
>> It's not bad as is, except for ultrafast mode.  START_DEBIT is the
>> biggest problem there.  I don't think SCHED_OTHER will ever match
>> SCHED_BATCH for this load, though I must say I haven't full-spectrum
>> tested.  This load really wants RR scheduling, and wakeup preemption
>> necessarily perturbs run order.
>>
>> I'll probably piddle with it some more, it's an interesting load.
> Yes, i must say, very interresting, its very complicated and... oh wait,
> its just encoding a movie!

Your trolling is becoming a bit over-the-top at this point.  You
should also considering replying to multiple people in one email as
opposed to spamming a whole bunch in sequence.

Perhaps as the lead x264 developer I'm qualified to say that it
certainly is a very complicated load due to the strict ordering
requirements of the threading model--and that you should tone down the
whining just a tad and perhaps read a bit more about how BFS and CFS
work before complaining about them.

Jason
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