From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751776AbZH1Kjs (ORCPT ); Fri, 28 Aug 2009 06:39:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751451AbZH1Kjs (ORCPT ); Fri, 28 Aug 2009 06:39:48 -0400 Received: from casper.infradead.org ([85.118.1.10]:50736 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751349AbZH1Kjr (ORCPT ); Fri, 28 Aug 2009 06:39:47 -0400 Subject: Re: [PATCH 15/15] x86: Fix cpu_coregroup_mask to return correct cpumask on multi-node processors From: Peter Zijlstra To: Andreas Herrmann Cc: Ingo Molnar , linux-kernel@vger.kernel.org In-Reply-To: <20090827152551.GE13576@alberich.amd.com> References: <20090820131243.GO29327@alberich.amd.com> <20090820134604.GD29327@alberich.amd.com> <1251128176.7538.301.camel@twins> <20090825093101.GJ20811@alberich.amd.com> <1251194143.7538.1128.camel@twins> <20090827152551.GE13576@alberich.amd.com> Content-Type: text/plain Date: Fri, 28 Aug 2009 12:39:44 +0200 Message-Id: <1251455984.17617.5.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2009-08-27 at 17:25 +0200, Andreas Herrmann wrote: > On Tue, Aug 25, 2009 at 11:55:43AM +0200, Peter Zijlstra wrote: > > On Tue, 2009-08-25 at 11:31 +0200, Andreas Herrmann wrote: > > > On Mon, Aug 24, 2009 at 05:36:16PM +0200, Peter Zijlstra wrote: > > > > On Thu, 2009-08-20 at 15:46 +0200, Andreas Herrmann wrote: > > > > > The correct mask that describes core-siblings of an processor > > > > > is topology_core_cpumask. See topology adapation patches, especially > > > > > http://marc.info/?l=linux-kernel&m=124964999608179 > > > > > > > > > > > > argh, violence, murder kill.. this is the worst possible hack and you're > > > > extending it :/ > > > > > > So this is the third code area > > > (besides sched_*_power_savings sysfs interface, and the __cpu_power fiddling) > > > that is crap, mess, a hack. > > > > > > Didn't know that I'd enter such a minefield when touching this code. ;-( > > > > Yeah, you're lucky that way ;-) Its been creaking for a while, and I've > > been making noises to the IBM people (who so far have been the main > > source of power saving patches) to clean this up, but now you trod onto > > all of it at once.. > > > > > What would be your perferred solution for the > > > core_cpumask/llc_shared_map stuff? Another domain level to get rid of > > > this function? > > > > Right, I'd like to see everything exposed as domain levels. > > > > > > numa-cluster > > numa > > socket > > in-socket-numa > > multi-core > > shared-cache > > core > > threads > > Out of curiosity, when does cpu_core_mask differ from llc_shared_map > on Intel? Only in case of MCM (e.g. Core2 Quad)? Yes, I think both c2q and some dual-core opteron have multiple cache domains per socket. > If yes, the hackery of cpu_coregroup_mask() could be replace by > the domain that I'd like to introduce for Magny-Cours: > > MC domain span would represent one die. > The new domain would span all dies in an MCM. > > Bad idea? No, I think all the mentioned chips have the multi-die thing in common, the intel c2q has 2 dual-core dies, the opteron I have seems to be two single cores and this magny thing has 2 many cores -- teh pun, sides aching :-) So the generalization to dies per socket seems sensible.