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

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Message-Id: <200705200246.22444.kernel@prachanda.hub>
Date:	Sun, 20 May 2007 02:46:19 +0530
From:	Anant Nitya <kernel@...chanda.info>
To:	linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...e.hu>,
	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

On Friday 18 May 2007 15:56:07 Ingo Molnar wrote:
> * 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,
Hi Ingo,

Please ignore my last report about lag problem while using CFS-v13, it is 
working perfectly fine with 2.6.21.1 and the lag I used to see in v12 is not 
there with v13 anymore. After digging in a bit I found that problem is only 
occurring in 2.6.22-rc1 and it get fired by network usage while transmitting 
data upstream. I don't have any evidence that CFS is involved in lag problem 
since 2.6.22-rc1 with stock scheduler is also having same lag problem and it 
seems directly proportional with upstream speed while downstream doesn't 
shows any misbehavior { at lower upstream speed lag is less but with higher 
upstream speed system starts crawling and system load hitting to 70/75}. Lets 
see how 2.6.22-rc2 is doing.

Regards
Ananitya

>
> 	Ingo



-- 
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