From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754735Ab0CDDdW (ORCPT ); Wed, 3 Mar 2010 22:33:22 -0500 Received: from cantor2.suse.de ([195.135.220.15]:51405 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753953Ab0CDDdQ (ORCPT ); Wed, 3 Mar 2010 22:33:16 -0500 Date: Thu, 4 Mar 2010 14:33:12 +1100 From: Nick Piggin To: john stultz Cc: Thomas Gleixner , lkml , Clark Williams , John Kacur Subject: Re: Nick's vfs-scalability patches ported to 2.6.33-rt Message-ID: <20100304033312.GO8653@laptop> References: <1267163608.2002.9.camel@work-vm> <20100226060109.GH9738@laptop> <1267659090.4317.67.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1267659090.4317.67.camel@localhost.localdomain> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 03, 2010 at 03:31:30PM -0800, john stultz wrote: > On Fri, 2010-02-26 at 17:01 +1100, Nick Piggin wrote: > > On Thu, Feb 25, 2010 at 09:53:28PM -0800, john stultz wrote: > > > Hey Thomas, Nick, > > > I just wanted to let you know I've just finished forward porting Nick's > > > patches to 2.6.33-rc8-rt2. Luckily my forward port of Nick's patches to > > > 2.6.33 applies on top of the -rt tree without any collisions, and I've > > > added a handful of maybe sketchy fixups to get it working with -rt. > > > > > > You can find the patchset here: > > > http://sr71.net/~jstultz/dbench-scalability/patches/2.6.33-rc8-rt2/vfs-scale.33-rt.tar.bz2 > > > > > > Here's a chart showing how much these patches help dbench numbers on > > > ramfs: > > > http://sr71.net/~jstultz/dbench-scalability/graphs/2.6.33/ramfs-dbench.png > > > > > > I've not done any serious stress testing with the patchset yet, but > > > wanted to post it for your review. > > > > > > Nick: I'd appreciate any feedback as to if any of my forward porting has > > > gone awry. I'm still very green with respect to the vfs, so I don't > > > doubt there are some issues hiding here. > > > > BTW there are a few issues Al pointed out. We have to synchronize RCU > > after unregistering a filesystem so d_ops/i_ops doesn't go away, and > > mntput can sleep so we can't do it under RCU read lock. > > Does the following address this issue properly? As far as I could tell, yes that should solve the code reference problem. I don't see a problem with synchronizing RCU here. > > Signed-off-by: John Stultz > > diff --git a/fs/filesystems.c b/fs/filesystems.c > index a24c58e..3448e7c 100644 > --- a/fs/filesystems.c > +++ b/fs/filesystems.c > @@ -110,6 +110,7 @@ int unregister_filesystem(struct file_system_type * fs) > *tmp = fs->next; > fs->next = NULL; > write_unlock(&file_systems_lock); > + synchronize_rcu(); > return 0; > } > tmp = &(*tmp)->next; >