From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755262AbZBFTbt (ORCPT ); Fri, 6 Feb 2009 14:31:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752551AbZBFTbj (ORCPT ); Fri, 6 Feb 2009 14:31:39 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:39348 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753787AbZBFTbi (ORCPT ); Fri, 6 Feb 2009 14:31:38 -0500 Date: Fri, 6 Feb 2009 20:31:21 +0100 From: Ingo Molnar To: Ben Greear , Thomas Gleixner Cc: linux-kernel , len.brown@intel.com Subject: Re: PATCH: Allow over-ride of smp_found_cfg with kernel cmd-line option. Message-ID: <20090206193121.GA32634@elte.hu> References: <498B421D.9090609@candelatech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <498B421D.9090609@candelatech.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ben Greear wrote: > Allow user to keep smp_found_cfg set to 1 even if MADT > cannot be parsed. This works around funky BIOS on FWA-7304 > (VIA CN700 chipset) system, and possibly other systems as well. > Without this override, performance drops by around 15% on > network throughput tests on this system. The question is, _why_ does network performance drop? Do you have a before/after pair of /proc/interrupts output perhaps? Does the layout of IRQs change? The system is not SMP - so only something about UP-IOAPIC can be helpful to performance here - or some unknown effect. Ingo