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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C4A44C2BA83 for ; Thu, 13 Feb 2020 17:02:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3572206DB for ; Thu, 13 Feb 2020 17:02:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728531AbgBMRCZ (ORCPT ); Thu, 13 Feb 2020 12:02:25 -0500 Received: from outbound-smtp25.blacknight.com ([81.17.249.193]:52772 "EHLO outbound-smtp25.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727851AbgBMRCZ (ORCPT ); Thu, 13 Feb 2020 12:02:25 -0500 Received: from mail.blacknight.com (pemlinmail01.blacknight.ie [81.17.254.10]) by outbound-smtp25.blacknight.com (Postfix) with ESMTPS id 5DFE7B8875 for ; Thu, 13 Feb 2020 17:02:23 +0000 (GMT) Received: (qmail 7015 invoked from network); 13 Feb 2020 17:02:23 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.18.57]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 13 Feb 2020 17:02:23 -0000 Date: Thu, 13 Feb 2020 17:02:21 +0000 From: Mel Gorman To: Vincent Guittot Cc: Phil Auld , Hillf Danton , Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , linux-kernel , Parth Shah , Valentin Schneider Subject: Re: [RFC 2/4] sched/numa: replace runnable_load_avg by load_avg Message-ID: <20200213170220.GA3466@techsingularity.net> References: <20200212133715.GU3420@suse.de> <20200212194903.GS3466@techsingularity.net> <20200213131658.9600-1-hdanton@sina.com> <20200213134655.GX3466@techsingularity.net> <20200213150026.GB6541@lorien.usersys.redhat.com> <20200213151430.GY3466@techsingularity.net> <20200213163437.GZ3466@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: 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 Thu, Feb 13, 2020 at 05:38:31PM +0100, Vincent Guittot wrote: > > > Your test doesn't explicitly ensure that the 1 condition is met > > > > > > That being said, I'm not sure it's really a wrong thing ? I mean > > > load_balance will probably try to pull back some tasks on src but as > > > long as it is not a task with dst node as preferred node, it should > > > not be that harmfull > > > > My thinking was that if source has as many or more running tasks than > > the destination *after* the move that it's not harmful and does not add > > work for the load balancer. > > load_balancer will see an imbalance but fbq_classify_group/queue > should be there to prevent from pulling back tasks that are on the > preferred node but only other tasks > Yes, exactly. Between fbq_classify and migrate_degrades_locality, I'm expecting that the load balancer will only override NUMA balancing when there is no better option. When the imbalance check, I want to avoid the situation where NUMA balancing moves a task for locality, LB pulls it back for balance, NUMA retries the move etc because it's stupid. The locality matters but being continually dequeue/enqueue is unhelpful. While there might be grounds for relaxing the degree an imbalance is allowed across SD domains, I am avoiding looking in that direction again until the load balancer and NUMA balancer stop overriding each other for silly reasons (or the NUMA balancer fighting itself which can happen). -- Mel Gorman SUSE Labs