From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757874AbZAOCFr (ORCPT ); Wed, 14 Jan 2009 21:05:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753331AbZAOCFh (ORCPT ); Wed, 14 Jan 2009 21:05:37 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:58870 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753303AbZAOCFg (ORCPT ); Wed, 14 Jan 2009 21:05:36 -0500 Date: Wed, 14 Jan 2009 18:04:31 -0800 From: Andrew Morton To: Matthew Wilcox Cc: "Wilcox, Matthew R" , chinang.ma@intel.com, linux-kernel@vger.kernel.org, sharad.c.tripathi@intel.com, arjan@linux.intel.com, andi.kleen@intel.com, suresh.b.siddha@intel.com, harita.chilukuri@intel.com, douglas.w.styner@intel.com, peter.xihong.wang@intel.com, hubert.nueckel@intel.com, chris.mason@oracle.com, srostedt@redhat.com, linux-scsi@vger.kernel.org, Andrew Vasquez , Anirban Chakraborty Subject: Re: Mainline kernel OLTP performance update Message-Id: <20090114180431.f4a96543.akpm@linux-foundation.org> In-Reply-To: <20090115012147.GW29283@parisc-linux.org> References: <20090114163557.11e097f2.akpm@linux-foundation.org> <20090115012147.GW29283@parisc-linux.org> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 14 Jan 2009 18:21:47 -0700 Matthew Wilcox wrote: > On Wed, Jan 14, 2009 at 04:35:57PM -0800, Andrew Morton wrote: > > On Tue, 13 Jan 2009 15:44:17 -0700 > > "Wilcox, Matthew R" wrote: > > > > > > > (top-posting repaired. That @intel.com address is a bad influence ;)) > > Alas, that email address goes to an Outlook client. Not much to be done > about that. aspirin? > > (cc linux-scsi) > > > > > > This is latest 2.6.29-rc1 kernel OLTP performance result. Compare to > > > > 2.6.24.2 the regression is around 3.5%. > > > > > > > > Linux OLTP Performance summary > > > > Kernel# Speedup(x) Intr/s CtxSw/s us% sys% idle% iowait% > > > > 2.6.24.2 1.000 21969 43425 76 24 0 0 > > > > 2.6.27.2 0.973 30402 43523 74 25 0 1 > > > > 2.6.29-rc1 0.965 30331 41970 74 26 0 0 > > > But the interrupt rate went through the roof. > > Yes. I forget why that was; I'll have to dig through my archives for > that. Oh. I'd have thought that this alone could account for 3.5%. > > A 3.5% slowdown in this workload is considered pretty serious, isn't it? > > Yes. Anything above 0.3% is statistically significant. 1% is a big > deal. The fact that we've lost 3.5% in the last year doesn't make > people happy. There's a few things we've identified that have a big > effect: > > - Per-partition statistics. Putting in a sysctl to stop doing them gets > some of that back, but not as much as taking them out (even when > the sysctl'd variable is in a __read_mostly section). We tried a > patch from Jens to speed up the search for a new partition, but it > had no effect. I find this surprising. > - The RT scheduler changes. They're better for some RT tasks, but not > the database benchmark workload. Chinang has posted about > this before, but the thread didn't really go anywhere. > http://marc.info/?t=122903815000001&r=1&w=2 Well. It's more a case that it wasn't taken anywhere. I appear to have recently been informed that there have never been any CPU-scheduler-caused regressions. Please persist! > SLUB would have had a huge negative effect if we were using it -- on the > order of 7% iirc. SLQB is at least performance-neutral with SLAB. We really need to unblock that problem somehow. I assume that enterprise distros are shipping slab?