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

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Date:	Sun, 17 Jul 2011 10:46:30 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Matthew Wilcox <matthew@....cx>
Cc:	Anton Blanchard <anton@...ba.org>, npiggin@...nel.dk,
	viro@...iv.linux.org.uk, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
	Tim Chen <tim.c.chen@...ux.intel.com>
Subject: Re: vfsmount lock issues on very large ppc64 box

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

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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