From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030369AbXDJGYh (ORCPT ); Tue, 10 Apr 2007 02:24:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030410AbXDJGYh (ORCPT ); Tue, 10 Apr 2007 02:24:37 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:44294 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030369AbXDJGYg (ORCPT ); Tue, 10 Apr 2007 02:24:36 -0400 Date: Tue, 10 Apr 2007 08:24:22 +0200 From: Ingo Molnar To: "Siddha, Suresh B" Cc: akpm@linux-foundation.org, nickpiggin@yahoo.com.au, linux-kernel@vger.kernel.org Subject: Re: [patch] sched: align rq to cacheline boundary Message-ID: <20070410062421.GA23274@elte.hu> References: <20070409180853.GC3948@linux-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070409180853.GC3948@linux-os.sc.intel.com> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Siddha, Suresh B wrote: > Align the per cpu runqueue to the cacheline boundary. This will > minimize the number of cachelines touched during remote wakeup. > -static DEFINE_PER_CPU(struct rq, runqueues); > +static DEFINE_PER_CPU(struct rq, runqueues) ____cacheline_aligned_in_smp; ouch!! Now how did _that_ slip through. The runqueues had been cacheline-aligned for ages. Or at least, they were supposed to be. could you see any improvement in profiles or workloads with this patch applied? (just curious - it's an obviously right fix) > Signed-off-by: Suresh Siddha Acked-by: Ingo Molnar Ingo