From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932175Ab2AJOlc (ORCPT ); Tue, 10 Jan 2012 09:41:32 -0500 Received: from merlin.infradead.org ([205.233.59.134]:33145 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932075Ab2AJOlb convert rfc822-to-8bit (ORCPT ); Tue, 10 Jan 2012 09:41:31 -0500 Message-ID: <1326206478.2442.111.camel@twins> Subject: Re: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken From: Peter Zijlstra To: Arjan van de Ven Cc: Ingo Molnar , Suresh Siddha , Youquan Song , linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@zytor.com, akpm@linux-foundation.org, stable@vger.kernel.org, len.brown@intel.com, anhua.xu@intel.com, chaohong.guo@intel.com, Youquan Song Date: Tue, 10 Jan 2012 15:41:18 +0100 In-Reply-To: <4F0C4BF0.9090809@linux.intel.com> References: <1326099367-4166-1-git-send-email-youquan.song@intel.com> <1326103578.2442.50.camel@twins> <20120110001445.GA20542@linux-youquan.bj.intel.com> <1326107156.2442.59.camel@twins> <20120110055856.GA23741@linux-youquan.bj.intel.com> <1326153163.2366.7.camel@sbsiddha-mobl2> <20120110091805.GA28024@elte.hu> <4F0C4BF0.9090809@linux.intel.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2012-01-10 at 06:32 -0800, Arjan van de Ven wrote: > > a very good default would be to keep all tasks on one package until half > the cores in the package are busy, and then start spreading out. Does that still make sense when there's strong NUMA preference? By forcing stuff on a single package you increase the number of remote memory fetches (which generally generate more stalls), also the memory controllers need to stay awake anyway.