From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422913AbdDURLR (ORCPT ); Fri, 21 Apr 2017 13:11:17 -0400 Received: from merlin.infradead.org ([205.233.59.134]:40866 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162240AbdDURG7 (ORCPT ); Fri, 21 Apr 2017 13:06:59 -0400 Date: Fri, 21 Apr 2017 18:31:26 +0200 From: Peter Zijlstra To: Lauro Ramos Venancio Cc: lwang@redhat.com, riel@redhat.com, Mike Galbraith , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] sched/topology: move comment about asymmetric node setups Message-ID: <20170421163126.53xcwde43cs7k6mf@hirez.programming.kicks-ass.net> References: <1492717903-5195-1-git-send-email-lvenanci@redhat.com> <1492717903-5195-4-git-send-email-lvenanci@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1492717903-5195-4-git-send-email-lvenanci@redhat.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 20, 2017 at 04:51:42PM -0300, Lauro Ramos Venancio wrote: > @@ -612,7 +604,16 @@ static void init_overlap_sched_group(struct sched_domain *sd, > > sibling = *per_cpu_ptr(sdd->sd, i); > > - /* See the comment near build_group_mask(). */ > + /* > + * Asymmetric node setups can result in situations where the > + * domain tree is of unequal depth, make sure to skip domains > + * that already cover the entire range. > + * > + * In that case build_sched_domains() will have terminated the > + * iteration early and our sibling sd spans will be empty. > + * Domains should always include the CPU they're built on, so > + * check that. > + */ > if (!cpumask_test_cpu(i, sched_domain_span(sibling))) > continue; > FWIW, the topology that spawned all that is: 10,20,20,30 20,10,20,20 20,20,10,20 30,20,20,10