From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261578AbVGGSqu (ORCPT ); Thu, 7 Jul 2005 14:46:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261569AbVGGSqu (ORCPT ); Thu, 7 Jul 2005 14:46:50 -0400 Received: from tantale.fifi.org ([64.81.251.130]:6789 "EHLO tantale.fifi.org") by vger.kernel.org with ESMTP id S261578AbVGGSqp (ORCPT ); Thu, 7 Jul 2005 14:46:45 -0400 To: Sheo Shanker Prasad Cc: linux-kernel@vger.kernel.org Subject: Re: Disturbing wide variation in execution time References: <200507062344.53615.ssp@creativeresearch.org> Mail-Copies-To: nobody From: Philippe Troin Date: 07 Jul 2005 11:46:38 -0700 In-Reply-To: <200507062344.53615.ssp@creativeresearch.org> Message-ID: <87oe9eo3n5.fsf@ceramic.fifi.org> User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Sheo Shanker Prasad writes: > I will appreciate your help in eliminating a disturbing wide > variation (by a factors of 2 to 2.5) in the execution time of a test > (execution benchmark) program under identical conditions even when > the machine is freshly started (rebooted) and no other user program > is running (not even e-mail or Internet browser). > > I have a dual Opteron 250 (2.4 GHz) running SuSE 9.3 Pro & Linux > version 2.6.11.4-21.7-smp (geeko@buildhost) (gcc version 3.3.5 > 20050117 (prerelease) (SUSE Linux)) #1 SMP Thu Jun 2 14:23:14 UTC > 2005. The motherboard is Tyan Thunder K8W (S2885 ANRF) with AMI BIOS > > The machine has 4GB of PC3200 DDR RAM, two dimms on each CPU. > > The original machine bought from a vendor about 6 months ago. At > that time it was running SuSE 9.1 Pro and the execution time for the > same test program was consistently the same (around 2m 37s +/- a few > %). Then the mother board failed and the machine went totally > dead. The vendor then replaced the failed motherboard with a new > Tyan Thunder K8W and installed the SuSE 9.3. I am not sure whether > or not the AMI BIOS was also replaced. > > When the repaired machine was started, I began to notice the > disturbing wide variation and the frequect significant slow down of > the machine as exhibited by the factor of 2 to 2.5 increased > execution time of the test program as described above. Sometimes it > would be quite fast (executing at the original 2m 40s) and sometime > a factor of 2.5 slow, and sometimes with speed in between. 8< snip >8 1. Are you running an i386 kernel or an x86_64 kernel? 2. Which BIOS version? 3. Is node interleaving enabled in the BIOS? Phil.