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

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Message-ID: <1311007276.2707.37.camel@schen9-DESK>
Date:	Mon, 18 Jul 2011 09:41:16 -0700
From:	Tim Chen <tim.c.chen@...ux.intel.com>
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>,
	Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: vfsmount lock issues on very large ppc64 box



On Sat, 2011-07-16 at 19:04 -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.
> 

I've sent out a trial patch a while ago on this problem, but didn't get
a response back. Nick or Al, can you take another look at this patch now
that other folks are also running into this issue?

http://marc.info/?l=linux-fsdevel&m=130273200502778&w=2

Thanks.

Tim

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