From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757352AbYDCNOX (ORCPT ); Thu, 3 Apr 2008 09:14:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753316AbYDCNOQ (ORCPT ); Thu, 3 Apr 2008 09:14:16 -0400 Received: from relay2.sgi.com ([192.48.171.30]:58611 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751690AbYDCNOP (ORCPT ); Thu, 3 Apr 2008 09:14:15 -0400 Date: Thu, 3 Apr 2008 08:14:11 -0500 From: Paul Jackson To: Hidetoshi Seto Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, peterz@infradead.org, andi@firstfloor.org Subject: Re: [PATCH 1/2] Customize sched domain via cpuset Message-Id: <20080403081411.aae6a064.pj@sgi.com> In-Reply-To: <47F44D25.6030001@jp.fujitsu.com> References: <47F21BE3.5030705@jp.fujitsu.com> <20080401065534.a6267b96.pj@sgi.com> <47F34625.6000600@jp.fujitsu.com> <20080402061405.197c0c90.pj@sgi.com> <47F44D25.6030001@jp.fujitsu.com> Organization: SGI X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.12.0; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org H.Seto wrote: > I believe there are quite technical reasons why we have no "idle_map." I would not advocate a single system wide cpumask of idle CPUs. As Peter Zijlstra notes in a follow up post, that's too hot a cache line and clearly doesn't scale. But I would think it would be ok to have a separate cpumask per node, that marked just the node-local CPUs. We have other per-node data already. If we only support this optional load balancing level across the other CPUs on the same node (or smaller domains, such as the cores in a package), that should work, shouldn't it? > so I'll update my patch to take levels, getting in your suggestion. If you see a good solution here that you can provide, good. But if my brain storming ideas have problems, don't hesitate to object to them. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.940.382.4214