From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755432Ab0CDEFY (ORCPT ); Wed, 3 Mar 2010 23:05:24 -0500 Received: from e33.co.us.ibm.com ([32.97.110.151]:49949 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754977Ab0CDEFT (ORCPT ); Wed, 3 Mar 2010 23:05:19 -0500 Subject: Re: Nick's vfs-scalability patches ported to 2.6.33-rt From: john stultz To: Nick Piggin , Thomas Gleixner Cc: lkml , Clark Williams , John Kacur In-Reply-To: <20100304033312.GO8653@laptop> References: <1267163608.2002.9.camel@work-vm> <20100226060109.GH9738@laptop> <1267659090.4317.67.camel@localhost.localdomain> <20100304033312.GO8653@laptop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 03 Mar 2010 20:05:11 -0800 Message-ID: <1267675511.4317.78.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 Thu, 2010-03-04 at 14:33 +1100, Nick Piggin wrote: > 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. Good to hear! Thanks for the review Nick! Thomas: I ran a number of kernel-bench and dbench stress tests on this today and I've not seen any issues, so unless Nick has other issues, I think it should be ok to pull into -rt. You can grab the full patchset that builds ontop of 2.6.33-rt4 here: http://sr71.net/~jstultz/dbench-scalability/patches/2.6.33-rt4/vfs-scale.33-rt.tar.bz2 thanks -john