From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755185Ab0CCXbl (ORCPT ); Wed, 3 Mar 2010 18:31:41 -0500 Received: from e9.ny.us.ibm.com ([32.97.182.139]:50202 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753357Ab0CCXbf (ORCPT ); Wed, 3 Mar 2010 18:31:35 -0500 Subject: Re: Nick's vfs-scalability patches ported to 2.6.33-rt From: john stultz To: Nick Piggin Cc: Thomas Gleixner , lkml , Clark Williams , John Kacur In-Reply-To: <20100226060109.GH9738@laptop> References: <1267163608.2002.9.camel@work-vm> <20100226060109.GH9738@laptop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 03 Mar 2010 15:31:30 -0800 Message-ID: <1267659090.4317.67.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? 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;