Re: [patch]block: fix ioc locking warning

From: Shaohua Li
Date: Mon Feb 06 2012 - 20:12:15 EST


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.

> * Test with the this_q != locked_q trylock patch.
sure.

Thanks,
Shaohua

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