linux-kernel - Re: vfsmount lock issues on very large ppc64 box

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Date:	Mon, 18 Jul 2011 10:17:08 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Matthew Wilcox <matthew@....cx>, Anton Blanchard <anton@...ba.org>,
	npiggin@...nel.dk, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Tim Chen <tim.c.chen@...ux.intel.com>
Subject: Re: vfsmount lock issues on very large ppc64 box

Le dimanche 17 juillet 2011 à 10:46 +0200, Andi Kleen a écrit :
> On Sat, Jul 16, 2011 at 07:04:28PM -0600, Matthew Wilcox wrote:
> > On Sun, Jul 17, 2011 at 10:50:27AM +1000, Anton Blanchard wrote:
> > > Looking closer, all of these calls are in pipefs and sockfs.
> > > Since we never mount either filesystem they never get a long term
> > > reference and we always end up in the very slow write brlock path
> > > that takes a lock for each online CPU.
> > > 
> > > Here is a quick hack that takes a long term reference on pipefs
> > > and sockfs which fixes the problem. Any thoughts on how we should
> > > fix it properly?
> > 
> > I know Tim and Andi have been looking into this ... I forget what their
> > fix was though.
> 
> Tim posted a patch, but it wasn't applied for unknown reasons.
> 
> https://lkml.org/lkml/2011/4/13/561
> 

Could Tim respin his patch then ?

This problem hits even a two sockets machine.



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