[patch] voluntary-preempt-2.6.8-rc2-I4

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> > >  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.

there's one more new version:

  http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.8-rc2-I4

this fixes another rare bug: release_task() could trigger a 'Badness'
atomicity message when the right conditions occur on a preemptible
kernel. This bugfix also allowed the addition of might_sleep() checks
(and hence voluntary-preemption points) to dput() and fput(), two common
functions.

	Ingo
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