From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752911AbZJEOov (ORCPT ); Mon, 5 Oct 2009 10:44:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752768AbZJEOou (ORCPT ); Mon, 5 Oct 2009 10:44:50 -0400 Received: from one.firstfloor.org ([213.235.205.2]:56670 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082AbZJEOot (ORCPT ); Mon, 5 Oct 2009 10:44:49 -0400 To: Yinghai Lu Cc: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Suresh Siddha , Tejun Heo , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] x86: use near online node instead of round bin for numa From: Andi Kleen References: <4AC7974C.20304@kernel.org> Date: Mon, 05 Oct 2009 16:44:10 +0200 In-Reply-To: <4AC7974C.20304@kernel.org> (Yinghai Lu's message of "Sat, 03 Oct 2009 11:26:20 -0700") Message-ID: <87my45yk79.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/22.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yinghai Lu writes: > cpu to node mapping is set in following sequence: > 1. numa_init_array: set up roundbin from cpu to online node > 2. init_cpu_to_node: set that according to apicid_to_node[] according to srat > only handle that node is online, and leave other cpu on node > without ram (aka not online) to still round-bin > 3. later srat_detect_node for intel/amd, will use first_online node or near by > node. > > problem is that setup_per_cpu_areas() is called between 2 and 3. the per_cpu > for cpu on node with ram is on different node. and could put that on node with > two hops away. > > so try add find_near_online_node() and call int init_cpu_to_node() This fallback case should not really happen anyways, unless the BIOS is buggy (in this case it might better to completely reject the SRAT because more might be wrong). Do you have a system where this is needed? -Andi -- ak@linux.intel.com -- Speaking for myself only.