From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752823AbaDYQGQ (ORCPT ); Fri, 25 Apr 2014 12:06:16 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:51911 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752637AbaDYQGE (ORCPT ); Fri, 25 Apr 2014 12:06:04 -0400 Date: Fri, 25 Apr 2014 18:05:53 +0200 From: Peter Zijlstra To: Vincent Guittot Cc: Dietmar Eggemann , "mingo@kernel.org" , "linux-kernel@vger.kernel.org" , "tony.luck@intel.com" , "fenghua.yu@intel.com" , "schwidefsky@de.ibm.com" , "cmetcalf@tilera.com" , "benh@kernel.crashing.org" , "linux@arm.linux.org.uk" , "linux-arm-kernel@lists.infradead.org" , "preeti@linux.vnet.ibm.com" , "linaro-kernel@lists.linaro.org" Subject: Re: [PATCH v4 5/5] sched: ARM: create a dedicated scheduler topology table Message-ID: <20140425160553.GW13658@twins.programming.kicks-ass.net> References: <1397209481-28542-1-git-send-email-vincent.guittot@linaro.org> <1397209481-28542-6-git-send-email-vincent.guittot@linaro.org> <5357A802.1030804@arm.com> <5357DBA5.1010106@arm.com> <53590835.9090803@arm.com> <20140425160419.GL11096@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140425160419.GL11096@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 25, 2014 at 06:04:19PM +0200, Peter Zijlstra wrote: > > The example above is consistent because CPU2 mask and CPU0 mask are > > fully exclusive > > > > so > > CPU0: cpu_corepower_mask=0-1 > > CPU2: cpu_corepower_mask=2 > > are consistent > > > > CPU0: cpu_corepower_mask=0-2 > > CPU2: cpu_corepower_mask=0-2 > > are also consistent > > > > but > > > > CPU0: cpu_corepower_mask=0-1 > > CPU2: cpu_corepower_mask=0-2 > > are not consistent > > > > and your example uses the last configuration > > > > To be more precise, the rule above applies on default SDT definition > > but the flag SD_OVERLAP enables such kind of overlap between group. > > Have you tried it ? > > I've never tried degenerate stuff with SD_OVERLAP, it might horribly > explode -- its not actually meant to work. > > The SD_OVERLAP comes from not fully connected NUMA topologies; suppose > something like: > > 0------1 > | | > | | > 2------3 > > or: > > ( 10 20 20 0 ) > ( 20 10 0 20 ) > ( 20 0 10 20 ) > ( 0 20 20 10 ) d'0h: s/0/30/ 0 <-> 3 is 2 hops, too focused on the single hop case > Your domain level that models the single-hop/20 distance has overlapping > masks: > > N0: 0-2 > N1: 0,1,3 > N2: 0,2,3 > N3: 1-3 > > I've never tried to construct a NUMA topology that would be overlapping > and have redundant bits in.