From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3E498C433F5 for ; Mon, 10 Sep 2018 09:41:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 026D820866 for ; Mon, 10 Sep 2018 09:41:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 026D820866 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728108AbeIJOfB (ORCPT ); Mon, 10 Sep 2018 10:35:01 -0400 Received: from outbound-smtp08.blacknight.com ([46.22.139.13]:37861 "EHLO outbound-smtp08.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728093AbeIJOfA (ORCPT ); Mon, 10 Sep 2018 10:35:00 -0400 Received: from mail.blacknight.com (pemlinmail05.blacknight.ie [81.17.254.26]) by outbound-smtp08.blacknight.com (Postfix) with ESMTPS id 13B1A1C313A for ; Mon, 10 Sep 2018 10:41:49 +0100 (IST) Received: (qmail 12986 invoked from network); 10 Sep 2018 09:41:48 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.229.88]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 10 Sep 2018 09:41:48 -0000 Date: Mon, 10 Sep 2018 10:41:47 +0100 From: Mel Gorman To: Peter Zijlstra Cc: Srikar Dronamraju , Ingo Molnar , Rik van Riel , LKML Subject: Re: [PATCH 4/4] sched/numa: Do not move imbalanced load purely on the basis of an idle CPU Message-ID: <20180910094147.GH1719@techsingularity.net> References: <20180907101139.20760-1-mgorman@techsingularity.net> <20180907101139.20760-5-mgorman@techsingularity.net> <20180907113309.GU24106@hirez.programming.kicks-ass.net> <20180907123739.GE1719@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20180907123739.GE1719@techsingularity.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 07, 2018 at 01:37:39PM +0100, Mel Gorman wrote: > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > > index d59d3e00a480..d4c289c11012 100644 > > > --- a/kernel/sched/fair.c > > > +++ b/kernel/sched/fair.c > > > @@ -1560,7 +1560,7 @@ static bool task_numa_compare(struct task_numa_env *env, > > > goto unlock; > > > > > > if (!cur) { > > > - if (maymove || imp > env->best_imp) > > > + if (maymove) > > > goto assign; > > > else > > > goto unlock; > > > > Srikar's patch here: > > > > http://lkml.kernel.org/r/1533276841-16341-4-git-send-email-srikar@linux.vnet.ibm.com > > > > Also frobs this condition, but in a less radical way. Does that yield > > similar results? > > I can check. I do wonder of course if the less radical approach just means > that automatic NUMA balancing and the load balancer simply disagree about > placement at a different time. It'll take a few days to have an answer as > the battery of workloads to check this take ages. > Tests completed over the weekend and I've found that the performance of both patches are very similar for two machines (both 2 socket) running a variety of workloads. Hence, I'm not worried about which patch gets picked up. However, I would prefer my own on the grounds that the additional complexity does not appear to get us anything. Of course, that changes if Srikar's tests on his larger ppc64 machines show the more complex approach is justified. -- Mel Gorman SUSE Labs