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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 8C808C00449 for ; Mon, 1 Oct 2018 10:05:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C83A2084C for ; Mon, 1 Oct 2018 10:05:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5C83A2084C 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 S1729238AbeJAQmb (ORCPT ); Mon, 1 Oct 2018 12:42:31 -0400 Received: from outbound-smtp27.blacknight.com ([81.17.249.195]:46670 "EHLO outbound-smtp27.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729092AbeJAQma (ORCPT ); Mon, 1 Oct 2018 12:42:30 -0400 Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp27.blacknight.com (Postfix) with ESMTPS id 8C015B8840 for ; Mon, 1 Oct 2018 11:05:26 +0100 (IST) Received: (qmail 4703 invoked from network); 1 Oct 2018 10:05:26 -0000 Received: from unknown (HELO stampy.163woodhaven.lan) (mgorman@techsingularity.net@[37.228.229.88]) by 81.17.254.9 with ESMTPA; 1 Oct 2018 10:05:26 -0000 From: Mel Gorman To: Peter Zijlstra Cc: Ingo Molnar , Srikar Dronamraju , Jirka Hladky , Rik van Riel , LKML , Linux-MM , Mel Gorman Subject: [PATCH 2/2] mm, numa: Migrate pages to local nodes quicker early in the lifetime of a task Date: Mon, 1 Oct 2018 11:05:25 +0100 Message-Id: <20181001100525.29789-3-mgorman@techsingularity.net> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20181001100525.29789-1-mgorman@techsingularity.net> References: <20181001100525.29789-1-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Automatic NUMA Balancing uses a multi-stage pass to decide whether a page should migrate to a local node. This filter avoids excessive ping-ponging if a page is shared or used by threads that migrate cross-node frequently. Threads inherit both page tables and the preferred node ID from the parent. This means that threads can trigger hinting faults earlier than a new task which delays scanning for a number of seconds. As it can be load balanced very early in its lifetime there can be an unnecessary delay before it starts migrating thread-local data. This patch migrates private pages faster early in the lifetime of a thread using the sequence counter as an identifier of new tasks. With this patch applied, STREAM performance is the same as 4.17 even though processes are not spread cross-node prematurely. Other workloads showed a mix of minor gains and losses. This is somewhat expected most workloads are not very sensitive to the starting conditions of a process. 4.19.0-rc5 4.19.0-rc5 4.17.0 numab-v1r1 fastmigrate-v1r1 vanilla MB/sec copy 43298.52 ( 0.00%) 47335.46 ( 9.32%) 47219.24 ( 9.06%) MB/sec scale 30115.06 ( 0.00%) 32568.12 ( 8.15%) 32527.56 ( 8.01%) MB/sec add 32825.12 ( 0.00%) 36078.94 ( 9.91%) 35928.02 ( 9.45%) MB/sec triad 32549.52 ( 0.00%) 35935.94 ( 10.40%) 35969.88 ( 10.51%) Signed-off-by: Mel Gorman --- kernel/sched/fair.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 25c7c7e09cbd..7fc4a371bdd2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1392,6 +1392,17 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page, int last_cpupid, this_cpupid; this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); + last_cpupid = page_cpupid_xchg_last(page, this_cpupid); + + /* + * Allow first faults or private faults to migrate immediately early in + * the lifetime of a task. The magic number 4 is based on waiting for + * two full passes of the "multi-stage node selection" test that is + * executed below. + */ + if ((p->numa_preferred_nid == -1 || p->numa_scan_seq <= 4) && + (cpupid_pid_unset(last_cpupid) || cpupid_match_pid(p, last_cpupid))) + return true; /* * Multi-stage node selection is used in conjunction with a periodic @@ -1410,7 +1421,6 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page, * This quadric squishes small probabilities, making it less likely we * act on an unlikely task<->page relation. */ - last_cpupid = page_cpupid_xchg_last(page, this_cpupid); if (!cpupid_pid_unset(last_cpupid) && cpupid_to_nid(last_cpupid) != dst_nid) return false; -- 2.16.4