From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id EF76E6B004A for ; Thu, 18 Nov 2010 21:28:35 -0500 (EST) Date: Fri, 19 Nov 2010 13:28:24 +1100 From: Dave Chinner Subject: Re: [PATCH 00/13] IO-less dirty throttling Message-ID: <20101119022824.GB13830@dastard> References: <20101117035821.000579293@intel.com> <20101117072538.GO22876@dastard> <20101117100655.GA26501@localhost> <20101118014051.GR22876@dastard> <20101117175900.0d7878e5.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101117175900.0d7878e5.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Wu Fengguang , Jan Kara , Christoph Hellwig , Theodore Ts'o , Chris Mason , Peter Zijlstra , Mel Gorman , Rik van Riel , KOSAKI Motohiro , linux-mm , "linux-fsdevel@vger.kernel.org" , LKML List-ID: On Wed, Nov 17, 2010 at 05:59:00PM -0800, Andrew Morton wrote: > On Thu, 18 Nov 2010 12:40:51 +1100 Dave Chinner wrote: > > Yeah, sorry, should have posted them - I didn't because I snapped > > the numbers before the run had finished. Without series: > > > > 373.19user 14940.49system 41:42.17elapsed 612%CPU (0avgtext+0avgdata 82560maxresident)k > > 0inputs+0outputs (403major+2599763minor)pagefaults 0swaps > > > > With your series: > > > > 359.64user 5559.32system 40:53.23elapsed 241%CPU (0avgtext+0avgdata 82496maxresident)k > > 0inputs+0outputs (312major+2598798minor)pagefaults 0swaps > > > > So the wall time with your series is lower, and system CPU time is > > way down (as I've already noted) for this workload on XFS. > > How much of that benefit is an accounting artifact, moving work away > from the calling process's CPU and into kernel threads? As I spelled out in my original results, the sustained CPU usage for the unmodified kernel is ~780% - 620% fs_mark, 80% bdi-flusher, 80% kswapd (i.e. completely CPU bound on the 8p test VM). With this series, the sustained CPU usage is about 380% - 250% fs_mark, 80% bdi-flusher, 50% kswapd. IOWs, this series _halved_ the total sustained CPU usage even after taking into account all the kernel threads. With wall time also being reduced and the number of IOs issued dropping by 25%, I find it hard to classify the result as anything other than spectacular... Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org