From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id J44qBLQRGVuPKQAAmS7hNA ; Thu, 07 Jun 2018 11:07:21 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 048A0608C1; Thu, 7 Jun 2018 11:07:21 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 8B041606DD; Thu, 7 Jun 2018 11:07:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 8B041606DD Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753552AbeFGLHS (ORCPT + 25 others); Thu, 7 Jun 2018 07:07:18 -0400 Received: from mx2.suse.de ([195.135.220.15]:36848 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753088AbeFGLHR (ORCPT ); Thu, 7 Jun 2018 07:07:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext-too.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 7F4BBACA5; Thu, 7 Jun 2018 11:07:15 +0000 (UTC) Date: Thu, 7 Jun 2018 13:07:13 +0200 From: Michal Hocko To: Jakub Racek Cc: linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Len Brown , linux-acpi@vger.kernel.org, Mel Gorman , linux-mm@kvack.org Subject: Re: [4.17 regression] Performance drop on kernel-4.17 visible on Stream, Linpack and NAS parallel benchmarks Message-ID: <20180607110713.GJ32433@dhcp22.suse.cz> References: <20180606122731.GB27707@jra-laptop.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180606122731.GB27707@jra-laptop.brq.redhat.com> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [CCing Mel and MM mailing list] On Wed 06-06-18 14:27:32, Jakub Racek wrote: > Hi, > > There is a huge performance regression on the 2 and 4 NUMA node systems on > stream benchmark with 4.17 kernel compared to 4.16 kernel. Stream, Linpack > and NAS parallel benchmarks show upto 50% performance drop. > > When running for example 20 stream processes in parallel, we see the following behavior: > > * all processes are started at NODE #1 > * memory is also allocated on NODE #1 > * roughly half of the processes are moved to the NODE #0 very quickly. * > however, memory is not moved to NODE #0 and stays allocated on NODE #1 > > As the result, half of the processes are running on NODE#0 with memory being > still allocated on NODE#1. This leads to non-local memory accesses > on the high Remote-To-Local Memory Access Ratio on the numatop charts. > > So it seems that 4.17 is not doing a good job to move the memory to the right NUMA > node after the process has been moved. > > ----8<---- > > The above is an excerpt from performance testing on 4.16 and 4.17 kernels. > > For now I'm merely making sure the problem is reported. Do you have numa balancing enabled? -- Michal Hocko SUSE Labs