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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 AB2DCC2D0DB for ; Mon, 20 Jan 2020 17:27:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 869DA21835 for ; Mon, 20 Jan 2020 17:27:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727114AbgATR10 (ORCPT ); Mon, 20 Jan 2020 12:27:26 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:30608 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726642AbgATR10 (ORCPT ); Mon, 20 Jan 2020 12:27:26 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 00KHRNri121570 for ; Mon, 20 Jan 2020 12:27:24 -0500 Received: from e06smtp04.uk.ibm.com (e06smtp04.uk.ibm.com [195.75.94.100]) by mx0a-001b2d01.pphosted.com with ESMTP id 2xmgbp9qd5-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 20 Jan 2020 12:27:24 -0500 Received: from localhost by e06smtp04.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 20 Jan 2020 17:27:10 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 00KHR9GP58917074 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 20 Jan 2020 17:27:09 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3E7224C04A; Mon, 20 Jan 2020 17:27:09 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0D3C34C05A; Mon, 20 Jan 2020 17:27:07 +0000 (GMT) Received: from linux.vnet.ibm.com (unknown [9.126.150.29]) by d06av22.portsmouth.uk.ibm.com (Postfix) with SMTP; Mon, 20 Jan 2020 17:27:06 +0000 (GMT) Date: Mon, 20 Jan 2020 22:57:06 +0530 From: Srikar Dronamraju To: Mel Gorman Cc: Vincent Guittot , Phil Auld , Ingo Molnar , Peter Zijlstra , Valentin Schneider , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Hillf Danton , Parth Shah , Rik van Riel , LKML Subject: Re: [PATCH] sched, fair: Allow a small load imbalance between low utilisation SD_NUMA domains v4 Reply-To: Srikar Dronamraju References: <20200114101319.GO3466@techsingularity.net> <20200117175631.GC20112@linux.vnet.ibm.com> <20200117215853.GS3466@techsingularity.net> <20200120080935.GD20112@linux.vnet.ibm.com> <20200120083354.GT3466@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20200120083354.GT3466@techsingularity.net> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 x-cbid: 20012017-0016-0000-0000-000002DF23A6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 20012017-0017-0000-0000-00003341C877 Message-Id: <20200120172706.GE20112@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-01-20_07:2020-01-20,2020-01-20 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 mlxlogscore=999 spamscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 mlxscore=0 bulkscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-2001200147 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > And this is why I'm curious as to why your workload is affected at all > because it uses many tasks. I stopped allowing an imbalance for higher > task counts partially on the basis of your previous report. > With this hunk on top of your patch and 5 runs of numa02, there were 0 traces. diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ade7a8dca5e4..7506cf67bde8 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8714,8 +8714,10 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s * the risk that lower domains have to be rebalanced. */ imbalance_min = 2; - if (busiest->sum_nr_running <= imbalance_min) + if (busiest->sum_nr_running <= imbalance_min) { + trace_printk("Reseting imbalance: busiest->sum_nr_running=%d, local->sum_nr_running=%d\n", busiest->sum_nr_irunning, local->sum_nr_running); env->imbalance = 0; + } } return; perf stat for the 5 iterations this time shows: 77.817 +- 0.995 seconds time elapsed ( +- 1.28% ) which I think is significantly less than last time around. So I think it may be some other noise that could have contributed to the jump last time. Also since the time consumption of numa02 is very small, a small disturbance can show up as a big number from a percentage perspective. -- Thanks and Regards Srikar Dronamraju