From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755568AbaAHIBp (ORCPT ); Wed, 8 Jan 2014 03:01:45 -0500 Received: from ipmail06.adl6.internode.on.net ([150.101.137.145]:24856 "EHLO ipmail06.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755182AbaAHIB2 (ORCPT ); Wed, 8 Jan 2014 03:01:28 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AigKAFIFzVK2/3kU/2dsb2JhbABZgwuDOaMhjlaFVIEQFnSCJQEBAQQ6PxAIAw0LCSUPBSg0iAPERRePBQcWgw6BEwSYFoZtiymDQSg Date: Tue, 7 Jan 2014 00:10:42 +1100 From: Dave Chinner To: fengguang.wu@intel.com Cc: Glauber Costa , Linux Memory Management List , linux-fsdevel@vger.kernel.org, LKML , lkp@linux.intel.com Subject: Re: [numa shrinker] 9b17c62382: -36.6% regression on sparse file copy Message-ID: <20140106131042.GA5145@destitution> References: <20140106082048.GA567@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140106082048.GA567@localhost> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 06, 2014 at 04:20:48PM +0800, fengguang.wu@intel.com wrote: > Hi Dave, > > We noticed throughput drop in test case > > vm-scalability/300s-lru-file-readtwice (*) > > between v3.11 and v3.12, and it's still low as of v3.13-rc6: > > v3.11 v3.12 v3.13-rc6 > --------------- ------------------------- ------------------------- > 14934707 ~ 0% -48.8% 7647311 ~ 0% -47.6% 7829487 ~ 0% vm-scalability.throughput > ^^ ^^^^^^ > stddev% change% What does this vm-scalability.throughput number mean? > (*) The test case basically does > > truncate -s 135080058880 /tmp/vm-scalability.img > mkfs.xfs -q /tmp/vm-scalability.img > mount -o loop /tmp/vm-scalability.img /tmp/vm-scalability > > nr_cpu=120 > for i in $(seq 1 $nr_cpu) > do > sparse_file=/tmp/vm-scalability/sparse-lru-file-readtwice-$i > truncate $sparse_file -s 36650387592 > dd if=$sparse_file of=/dev/null & > dd if=$sparse_file of=/dev/null & > done So a page cache load of reading 120x36GB files twice concurrently? There's no increase in system time, so it can't be that the shrinkers are running wild. FWIW, I'm at LCA right now, so it's going to be a week before I can look at this, so if you can find any behavioural difference in the shrinkers (e.g. from perf profiles, on different filesystems, etc) I'd appreciate it... Cheers, Dave. -- Dave Chinner david@fromorbit.com