From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752481AbaJLN2v (ORCPT ); Sun, 12 Oct 2014 09:28:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19637 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751115AbaJLN2u (ORCPT ); Sun, 12 Oct 2014 09:28:50 -0400 Message-ID: <543A81E4.4090504@redhat.com> Date: Sun, 12 Oct 2014 09:28:04 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Peter Zijlstra CC: linux-kernel@vger.kernel.org, mgorman@suse.de, chegu_vinod@hp.com, mingo@kernel.org, efault@gmx.de, vincent.guittot@linaro.org Subject: Re: [PATCH RFC 1/5] sched,numa: build table of node hop distance References: <1412797050-8903-1-git-send-email-riel@redhat.com> <1412797050-8903-2-git-send-email-riel@redhat.com> <20141012131714.GE3015@worktop> In-Reply-To: <20141012131714.GE3015@worktop> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/12/2014 09:17 AM, Peter Zijlstra wrote: > On Wed, Oct 08, 2014 at 03:37:26PM -0400, riel@redhat.com wrote: >> + sched_domains_numa_hops = kzalloc(sizeof(int) * nr_node_ids * nr_node_ids, GFP_KERNEL); >> + if (!sched_domains_numa_hops) >> + return; > > That's potentially a _BIG_ table (1M for a 512 node system). > The node_distance has magic allocations and is of u8 size, is there any > way we can re-use node_distance and avoid a second O(n^2) allocation? You are right, this should be a u8 at the least. Beyond that, I am not convinced that merging things into the same array is worthwhile, since (IIRC) nr_node_ids should be set to the actual number of nodes on the system by then.