Re: [patch]block: fix ioc locking warning

From: Shaohua Li
Date: Mon Feb 06 2012 - 20:35:19 EST

On Tue, 2012-02-07 at 09:10 +0800, Shaohua Li wrote:
> On Mon, 2012-02-06 at 16:59 -0800, Tejun Heo wrote:
> > On Tue, Feb 07, 2012 at 08:43:50AM +0800, Shaohua Li wrote:
> > > Quite simple, copy kernel source to tmpfs in tight memory environment.
> > > This will trigger swap. The bisection result appears stable.
> >
> > Looked through the commit again but it really doesn't change fast
> > paths. The only paths which can be slower are ioc and q exits. Can
> > you please do the followings?
> >
> > * Share the script used for microbench. Maybe it somehow exposes
> > slower exit path? How much regression are we talking about?
> I need strip the script out from our test framework, but it essentially
> is a 'time copy -a tmpfs/kernelsource tmpfs/copy'. The time increased
> ~20% with 3.3-rc1.
oops, I get confused about our swap and swap-cp test. The workload with
regression is swap. which does 'time kernelbuild tmpfs/kernelsource'. we
run several such kernelbuild in the meantime to trigger swap. Very sorry
to give your wrong info before.

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