From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759212AbZCBDNV (ORCPT ); Sun, 1 Mar 2009 22:13:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752115AbZCBDNM (ORCPT ); Sun, 1 Mar 2009 22:13:12 -0500 Received: from mga14.intel.com ([143.182.124.37]:44228 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752127AbZCBDNM (ORCPT ); Sun, 1 Mar 2009 22:13:12 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.38,286,1233561600"; d="scan'208";a="115620330" Date: Mon, 2 Mar 2009 11:12:27 +0800 From: Wu Fengguang To: Lin Ming Cc: Peter Zijlstra , "npiggin@suse.de" , linux-kernel , "Zhang, Yanmin" Subject: Re: iozone regression with 2.6.29-rc6 Message-ID: <20090302031227.GA6686@localhost> References: <1235726039.11610.243.camel@minggr> <1235728154.24401.55.camel@laptop> <1235960344.11610.246.camel@minggr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1235960344.11610.246.camel@minggr> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 02, 2009 at 10:19:04AM +0800, Lin, Ming wrote: > On Fri, 2009-02-27 at 17:49 +0800, Peter Zijlstra wrote: > > On Fri, 2009-02-27 at 17:13 +0800, Lin Ming wrote: > > > bisect locates below commits, > > > > > > commit 1cf6e7d83bf334cc5916137862c920a97aabc018 > > > Author: Nick Piggin > > > Date: Wed Feb 18 14:48:18 2009 -0800 > > > > > > mm: task dirty accounting fix > > > > > > YAMAMOTO-san noticed that task_dirty_inc doesn't seem to be called properly for > > > cases where set_page_dirty is not used to dirty a page (eg. mark_buffer_dirty). > > > > > > Additionally, there is some inconsistency about when task_dirty_inc is > > > called. It is used for dirty balancing, however it even gets called for > > > __set_page_dirty_no_writeback. > > > > > > So rather than increment it in a set_page_dirty wrapper, move it down to > > > exactly where the dirty page accounting stats are incremented. > > > > > > Cc: YAMAMOTO Takashi > > > Signed-off-by: Nick Piggin > > > Acked-by: Peter Zijlstra > > > Signed-off-by: Andrew Morton > > > Signed-off-by: Linus Torvalds > > > > > > > > > below data in parenthesis is the result after above commit reverted, for example, > > > -10% (+2%) means, > > > iozone has ~10% regression with 2.6.29-rc6 compared with 2.6.29-rc5. > > > and > > > iozone has ~2% improvement with 2.6.29-rc6-revert-1cf6e7d compared with 2.6.29-rc5. > > > > > > > > > 4P dual-core HT 2P qual-core 2P qual-core HT > > > tulsa stockley Nehalem > > > -------------------------------------------------------- > > > iozone-rewrite -10% (+2%) -8% (0%) -10% (-7%) > > > iozone-rand-write -50% (0%) -20% (+10%) > > > iozone-read -13% (0%) > > > iozone-write -28% (-1%) > > > iozone-reread -5% (-1%) > > > iozone-mmap-read -7% (+2%) > > > iozone-mmap-reread -7% (+2%) > > > iozone-mmap-rand-read -7% (+3%) > > > iozone-mmap-rand-write -5% (0%) > > > > Ugh, that's unexpected.. > > > > So 'better' accounting leads to worse performance, which would indicate > > we throttle more. > > > > I take it you machine has gobs of memory. > > > > Does something like the below help any? > > It helps some as below test result, > The data in second parenthesis means 2.6.29-rc6-with-peter's-patch > compared with 2.6.29-rc5. > > 4P dual-core HT 2P qual-core 2P qual-core HT > tulsa stockley Nehalem > -------------------------------------------------------- > iozone-rewrite -10% (+2%)(-3%) -8% (0%)(0%) -10% (-7%)(-2%) > iozone-rand-write -50% (0%)(-10%) -20% (+10%)(+3%) > iozone-read -13% (0%)(-8%) > iozone-write -28% (-1%)(+35%) > iozone-reread -5% (-1%)(-1%) > iozone-mmap-read -7% (+2%)(-7%) > iozone-mmap-reread -7% (+2%)(-7%) > iozone-mmap-rand-read -7% (+3%)(-7%) > iozone-mmap-rand-write -5% (0%)(+27%) Thanks, Lin Ming. To better understand the situation, would you please provide the iozone command and memory info about the servers? Thanks, Fengguang