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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 6701EC2BA83 for ; Fri, 14 Feb 2020 08:18:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FE5F2467D for ; Fri, 14 Feb 2020 08:18:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729007AbgBNISU (ORCPT ); Fri, 14 Feb 2020 03:18:20 -0500 Received: from outbound-smtp62.blacknight.com ([46.22.136.251]:36047 "EHLO outbound-smtp62.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728582AbgBNISU (ORCPT ); Fri, 14 Feb 2020 03:18:20 -0500 Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp62.blacknight.com (Postfix) with ESMTPS id 3AE54FAE5D for ; Fri, 14 Feb 2020 08:18:17 +0000 (GMT) Received: (qmail 16315 invoked from network); 14 Feb 2020 08:18:16 -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); 14 Feb 2020 08:18:16 -0000 Date: Fri, 14 Feb 2020 08:18:14 +0000 From: Mel Gorman To: Vincent Guittot Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Valentin Schneider , Phil Auld , Hillf Danton , LKML Subject: [PATCH 11/12] sched/numa: Bias swapping tasks based on their preferred node Message-ID: <20200214081814.GF3466@techsingularity.net> References: <20200214081324.26859-1-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20200214081324.26859-1-mgorman@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 When swapping tasks for NUMA balancing, it is preferred that tasks move to or remain on their preferred node. When considering an imbalance, encourage tasks to move to their preferred node and discourage tasks from moving away from their preferred node. Signed-off-by: Mel Gorman --- kernel/sched/fair.c | 43 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 37 insertions(+), 6 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d0ccd97658e9..d046fa97b7ef 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1741,18 +1741,27 @@ static void task_numa_compare(struct task_numa_env *env, goto unlock; } + /* Skip this swap candidate if cannot move to the source cpu. */ + if (!cpumask_test_cpu(env->src_cpu, cur->cpus_ptr)) + goto unlock; + + /* + * Skip this swap candidate if it is not moving to its preferred + * node and the best task is. + */ + if (env->best_task && + env->best_task->numa_preferred_nid == env->src_nid && + cur->numa_preferred_nid != env->src_nid) { + goto unlock; + } + /* * "imp" is the fault differential for the source task between the * source and destination node. Calculate the total differential for * the source task and potential destination task. The more negative * the value is, the more remote accesses that would be expected to * be incurred if the tasks were swapped. - */ - /* Skip this swap candidate if cannot move to the source cpu */ - if (!cpumask_test_cpu(env->src_cpu, cur->cpus_ptr)) - goto unlock; - - /* + * * If dst and source tasks are in the same NUMA group, or not * in any group then look only at task weights. */ @@ -1779,12 +1788,34 @@ static void task_numa_compare(struct task_numa_env *env, task_weight(cur, env->dst_nid, dist); } + /* Discourage picking a task already on its preferred node */ + if (cur->numa_preferred_nid == env->dst_nid) + imp -= imp / 16; + + /* + * Encourage picking a task that moves to its preferred node. + * This potentially makes imp larger than it's maximum of + * 1998 (see SMALLIMP and task_weight for why) but in this + * case, it does not matter. + */ + if (cur->numa_preferred_nid == env->src_nid) + imp += imp / 8; + if (maymove && moveimp > imp && moveimp > env->best_imp) { imp = moveimp; cur = NULL; goto assign; } + /* + * Prefer swapping with a task moving to its preferred node over a + * task that is not. + */ + if (env->best_task && cur->numa_preferred_nid == env->src_nid && + env->best_task->numa_preferred_nid != env->src_nid) { + goto assign; + } + /* * If the NUMA importance is less than SMALLIMP, * task migration might only result in ping pong -- 2.16.4