linux-kernel - Re: 2.6.21 known regressions (v2) (for -stable team)

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Date:	Sat, 28 Apr 2007 22:04:31 +0200
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Thomas Meyer <thomas@...3r.de>
Cc:	Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
	stable@...nel.org, Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Meyer <thomas.mey@....de>
Subject: Re: 2.6.21 known regressions (v2) (for -stable team)

On Sat, 2007-04-28 at 20:10 +0200, Thomas Meyer wrote:
> Thomas Gleixner schrieb:
> > On Sat, 2007-04-28 at 18:27 +0200, Michal Piotrowski wrote:
> >   
> >> Subject    : Bad interaction between dynticks and amarok?
> >> References : http://lkml.org/lkml/2007/4/26/307
> >> Submitter  : Thomas Meyer <thomas.mey@....de>
> >> Status     : Unknow
> >>     
> >
> > Michal,
> >
> > I don't think this is a regression. What Thomas wanted to point out is,
> > that the amarok / sound device is making the positive effect of dynticks
> > moot, as it starts to trigger useless interrupts.
> >
> > Thomas, is my interpretation correct ? Did you check, which interrupt
> > was increasing - i.e. was it the soundcard one ?
> >   
> No, it wasn't the soundcard one. but i had this effect with amarok and
> audacious... so, i guessed... which was wrong.
> 
> It's the timer interrupt (+50-70 timer interrupts). But i'm not sure
> what both applications are doing, while they are "idle"...

Ok, so amarok is one of those applications which arm timers for no
obvious reason. If you enable CONFIG_TIMER_STATS in the kernel, you can
analyse the timer offenders via the /proc/timer_stats interface.

	tglx


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