linux-kernel - Re: [patch] CFS scheduler, -v13

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Date:	Fri, 18 May 2007 12:26:07 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Anant Nitya <kernel@...chanda.info>
Cc:	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Con Kolivas <kernel@...ivas.org>,
	Nick Piggin <npiggin@...e.de>, Mike Galbraith <efault@....de>,
	Peter Williams <pwil3058@...pond.net.au>,
	Arjan van de Ven <arjan@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [patch] CFS scheduler, -v13


* Anant Nitya <kernel@...chanda.info> wrote:

> Hi
>
> Been testing this version of CFS from last an hour or so and still 
> facing same lag problems while browsing sites with heavy JS and or 
> flash usage. Mouse movement is pathetic and audio starts to skip. I 
> haven't face this behavior with CFS till v11.

i have just tried 5 different versions of the Flash plugin and i cannot 
reproduce this (flash games are still smooth and acceptable even with 
the system significantly overloaded with 5 infite loops or with a kernel 
build), so it would be nice if you could help me debug this problem.

The last version that worked for you was v11, correct? The biggest v11 
-> v12 change was the yield workaround, and while testing your workload 
i also noticed that all Flash versions except the latest one (9.0 r31) 
use sys_sched_yield() quite frequently. So it would be nice to know 
which plugin version you are using (and which Firefox version): you can 
check that by typing about:plugins into firefox. Furthermore, could you 
also try the following tune:

   echo 0 > /proc/sys/kernel/sched_yield_bug_workaround

and this:

   echo 2 > /proc/sys/kernel/sched_yield_bug_workaround

if none of this changes behavior then please send me the output of the 
following:

  strace -ttt -TTT -o strace.txt -f -p `pidof firefox-bin`
  < reproduce the lag in firefox >
  < Ctrl-C the strace >
  
and send me the strace.txt file (off-line, it's going to be large). 
Thanks,

	Ingo
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