From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935419AbYEVI2o (ORCPT ); Thu, 22 May 2008 04:28:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761775AbYEVI23 (ORCPT ); Thu, 22 May 2008 04:28:29 -0400 Received: from E23SMTP05.au.ibm.com ([202.81.18.174]:55743 "EHLO e23smtp05.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755566AbYEVI20 (ORCPT ); Thu, 22 May 2008 04:28:26 -0400 Date: Thu, 22 May 2008 13:58:14 +0530 From: Dhaval Giani To: Mike Galbraith Cc: Greg Smith , lkml , Peter Zijlstra , Ingo Molnar , Srivatsa Vaddagiri Subject: Re: PostgreSQL pgbench performance regression in 2.6.23+ Message-ID: <20080522082814.GA4499@linux.vnet.ibm.com> Reply-To: Dhaval Giani References: <1211440207.5733.8.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1211440207.5733.8.camel@marge.simson.net> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 22, 2008 at 09:10:07AM +0200, Mike Galbraith wrote: > > On Wed, 2008-05-21 at 13:34 -0400, Greg Smith wrote: > > PostgreSQL ships with a simple database benchmarking tool named pgbench, > > in what's labeled the contrib section (in many distributions it's a > > separate package from the main server/client ones). I see there's been > > some work done already improving how the PostgreSQL server works under the > > new scheduler (the "Poor PostgreSQL scaling on Linux 2.6.25-rc5" thread). > > I wanted to provide you a different test case using pgbench that has taken > > a sharp dive starting with 2.6.23, and the server improvement changes in > > 2.6.25 actually made this problem worse. > > > > I think it will be easy for someone else to replicate my results and I'll > > go over the exact procedure below. > > Yup, I can reproduce. Running the test with 2.6.25.4, everything is > waking/running on one CPU, leaving my box 75% idle. Not good. > Can you try with 2.6.26-rc? There is minimal load balancing for group scheduling till 25, which might explain the lack of scalability. -- regards, Dhaval