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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 A218AC6778F for ; Wed, 25 Jul 2018 14:25:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 588952088E for ; Wed, 25 Jul 2018 14:25:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 588952088E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com 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 S1729150AbeGYPhO (ORCPT ); Wed, 25 Jul 2018 11:37:14 -0400 Received: from terminus.zytor.com ([198.137.202.136]:33409 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728815AbeGYPhO (ORCPT ); Wed, 25 Jul 2018 11:37:14 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w6PEOssA402025 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 25 Jul 2018 07:24:54 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w6PEOsQD402022; Wed, 25 Jul 2018 07:24:54 -0700 Date: Wed, 25 Jul 2018 07:24:54 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Srikar Dronamraju Message-ID: Cc: mgorman@techsingularity.net, torvalds@linux-foundation.org, mingo@kernel.org, linux-kernel@vger.kernel.org, srikar@linux.vnet.ibm.com, riel@surriel.com, tglx@linutronix.de, hpa@zytor.com, peterz@infradead.org Reply-To: peterz@infradead.org, hpa@zytor.com, srikar@linux.vnet.ibm.com, tglx@linutronix.de, riel@surriel.com, linux-kernel@vger.kernel.org, mingo@kernel.org, mgorman@techsingularity.net, torvalds@linux-foundation.org In-Reply-To: <1529514181-9842-4-git-send-email-srikar@linux.vnet.ibm.com> References: <1529514181-9842-4-git-send-email-srikar@linux.vnet.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched/numa: Simplify load_too_imbalanced() Git-Commit-ID: 5f95ba7a43057f28a349ea1f03ee8d04e0f445ea X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 5f95ba7a43057f28a349ea1f03ee8d04e0f445ea Gitweb: https://git.kernel.org/tip/5f95ba7a43057f28a349ea1f03ee8d04e0f445ea Author: Srikar Dronamraju AuthorDate: Wed, 20 Jun 2018 22:32:44 +0530 Committer: Ingo Molnar CommitDate: Wed, 25 Jul 2018 11:41:06 +0200 sched/numa: Simplify load_too_imbalanced() Currently load_too_imbalance() cares about the slope of imbalance. It doesn't care of the direction of the imbalance. However this may not work if nodes that are being compared have dissimilar capacities. Few nodes might have more cores than other nodes in the system. Also unlike traditional load balance at a NUMA sched domain, multiple requests to migrate from the same source node to same destination node may run in parallel. This can cause huge load imbalance. This is specially true on a larger machines with either large cores per node or more number of nodes in the system. Hence allow move/swap only if the imbalance is going to reduce. Running SPECjbb2005 on a 4 node machine and comparing bops/JVM JVMS LAST_PATCH WITH_PATCH %CHANGE 16 25058.2 25122.9 0.25 1 72950 73850 1.23 (numbers from v1 based on v4.17-rc5) Testcase Time: Min Max Avg StdDev numa01.sh Real: 516.14 892.41 739.84 151.32 numa01.sh Sys: 153.16 192.99 177.70 14.58 numa01.sh User: 39821.04 69528.92 57193.87 10989.48 numa02.sh Real: 60.91 62.35 61.58 0.63 numa02.sh Sys: 16.47 26.16 21.20 3.85 numa02.sh User: 5227.58 5309.61 5265.17 31.04 numa03.sh Real: 739.07 917.73 795.75 64.45 numa03.sh Sys: 94.46 136.08 109.48 14.58 numa03.sh User: 57478.56 72014.09 61764.48 5343.69 numa04.sh Real: 442.61 715.43 530.31 96.12 numa04.sh Sys: 224.90 348.63 285.61 48.83 numa04.sh User: 35836.84 47522.47 40235.41 3985.26 numa05.sh Real: 386.13 489.17 434.94 43.59 numa05.sh Sys: 144.29 438.56 278.80 105.78 numa05.sh User: 33255.86 36890.82 34879.31 1641.98 Testcase Time: Min Max Avg StdDev %Change numa01.sh Real: 435.78 653.81 534.58 83.20 38.39% numa01.sh Sys: 121.93 187.18 145.90 23.47 21.79% numa01.sh User: 37082.81 51402.80 43647.60 5409.75 31.03% numa02.sh Real: 60.64 61.63 61.19 0.40 0.637% numa02.sh Sys: 14.72 25.68 19.06 4.03 11.22% numa02.sh User: 5210.95 5266.69 5233.30 20.82 0.608% numa03.sh Real: 746.51 808.24 780.36 23.88 1.972% numa03.sh Sys: 97.26 108.48 105.07 4.28 4.197% numa03.sh User: 58956.30 61397.05 60162.95 1050.82 2.661% numa04.sh Real: 465.97 519.27 484.81 19.62 9.385% numa04.sh Sys: 304.43 359.08 334.68 20.64 -14.6% numa04.sh User: 37544.16 41186.15 39262.44 1314.91 2.478% numa05.sh Real: 411.57 457.20 433.29 16.58 0.380% numa05.sh Sys: 230.05 435.48 339.95 67.58 -17.9% numa05.sh User: 33325.54 36896.31 35637.84 1222.64 -2.12% Signed-off-by: Srikar Dronamraju Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Rik van Riel Acked-by: Mel Gorman Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1529514181-9842-4-git-send-email-srikar@linux.vnet.ibm.com Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 20 ++------------------ 1 file changed, 2 insertions(+), 18 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index b10e0663a49e..226837960ec0 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1546,28 +1546,12 @@ static bool load_too_imbalanced(long src_load, long dst_load, src_capacity = env->src_stats.compute_capacity; dst_capacity = env->dst_stats.compute_capacity; - /* We care about the slope of the imbalance, not the direction. */ - if (dst_load < src_load) - swap(dst_load, src_load); - - /* Is the difference below the threshold? */ - imb = dst_load * src_capacity * 100 - - src_load * dst_capacity * env->imbalance_pct; - if (imb <= 0) - return false; + imb = abs(dst_load * src_capacity - src_load * dst_capacity); - /* - * The imbalance is above the allowed threshold. - * Compare it with the old imbalance. - */ orig_src_load = env->src_stats.load; orig_dst_load = env->dst_stats.load; - if (orig_dst_load < orig_src_load) - swap(orig_dst_load, orig_src_load); - - old_imb = orig_dst_load * src_capacity * 100 - - orig_src_load * dst_capacity * env->imbalance_pct; + old_imb = abs(orig_dst_load * src_capacity - orig_src_load * dst_capacity); /* Would this change make things worse? */ return (imb > old_imb);