Date: Thu, 26 Oct 2006 22:37:48 +0100
From: Al Viro <viro@ftp.linux.org.uk>
To: Avi Kivity <avi@argo.co.il>
Cc: Josef Sipek <jsipek@fsl.cs.sunysb.edu>, lkml@pengaru.com,
       linux-kernel@vger.kernel.org
Subject: Re: rename() contention (BUG?)
Message-ID: <20061026213748.GM29920@ftp.linux.org.uk>
References: <20061025205634.GB9100@shells.gnugeneration.com> <20061025211341.GB7128@filer.fsl.cs.sunysb.edu> <454101D6.9050004@argo.co.il> <20061026192219.GL29920@ftp.linux.org.uk> <4541267C.8040004@argo.co.il>
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On Thu, Oct 26, 2006 at 11:19:56PM +0200, Avi Kivity wrote:
> Al Viro wrote:
> >On Thu, Oct 26, 2006 at 08:43:34PM +0200, Avi Kivity wrote:
> >  
> >>The changes make the mutex more efficient, but won't decrease the 
> >>contention.  It seems that all renames in one filesystem are serialized, 
> >>and if the renames require I/O (which is certainly the case with nfs), 
> >>rename throughput is severely limited.
> >>    
> >
> >	They are, and for a good reason.  For details see
> >Documentation/filesystems/directory-locking.
> >  
> 
> Is it possible to lock only the common subtree of the two paths?
> 
> Perhaps walk towards the root of the tree, starting with the deeper 
> path, locking one component at a time.  Then walk both paths together 
> locking components ordered by something to avoid deadlock.

Please, read the file mentioned above.
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