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Date: Fri, 23 Jul 2004 13:42:37 +0200
From: Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com>
To: Ingo Molnar <mingo@elte.hu>
Subject: Re: [patch] voluntary-preempt-2.6.8-rc2-I3
Cc: linux-kernel@vger.kernel.org, Rudo Thomas <rudo@matfyz.cz>,
       Matt Heler <lkml@lpbproductions.com>
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On Fri, 23 Jul 2004 13:04:30 +0200, Ingo Molnar <mingo@elte.hu> wrote:
> 
> * Paolo Ciarrocchi <paolo.ciarrocchi@gmail.com> wrote:
> 
> > > i've uploaded the -I3 voluntary-preempt patch:
> > >
> > >  http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.8-rc2-I3
> > >
> > > it mainly fixes an ext3 livelock that could result in long delays during
> > > heavy commit traffic.
> >
> > Hello Ingo, do you have any measurement of the improvement available ?
> 
> it's a bug in the patch, not really a latency fix. When this (rare)
> condition under heavy write traffic occurs then kjournald would loop for
> many seconds (or tens of seconds) in __journal_clean_checkpoint_list(),
> effectively hanging the system. The system is still preemptible but the
> user cannot do much with it. Note that this condition is not present in
> the vanilla kernel, it got introduced by earlier versions of
> voluntary-preempt.

Hi Ingo,
thanks for the clarification.

What about performance of vanilla vs voluntary-preempt-2.6.8-rc2-I3 ?
Do you have numbers available ? Can we, somehow, support you ?

Ciao,
                Paolo