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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 16D0DC433F5 for ; Tue, 4 Sep 2018 09:01:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD23120843 for ; Tue, 4 Sep 2018 09:01:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AD23120843 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 S1727164AbeIDNZJ (ORCPT ); Tue, 4 Sep 2018 09:25:09 -0400 Received: from outbound-smtp12.blacknight.com ([46.22.139.17]:53480 "EHLO outbound-smtp12.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726061AbeIDNZI (ORCPT ); Tue, 4 Sep 2018 09:25:08 -0400 Received: from mail.blacknight.com (pemlinmail01.blacknight.ie [81.17.254.10]) by outbound-smtp12.blacknight.com (Postfix) with ESMTPS id 4A88D1C1D74 for ; Tue, 4 Sep 2018 10:00:55 +0100 (IST) Received: (qmail 30286 invoked from network); 4 Sep 2018 09:00:55 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.229.88]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 4 Sep 2018 09:00:55 -0000 Date: Tue, 4 Sep 2018 10:00:53 +0100 From: Mel Gorman To: Jirka Hladky Cc: Kamil Kolakowski , Jakub Racek , linux-kernel , "Rafael J. Wysocki" , Len Brown , linux-acpi@vger.kernel.org Subject: Re: [4.17 regression] Performance drop on kernel-4.17 visible on Stream, Linpack and NAS parallel benchmarks Message-ID: <20180904090053.GB1719@techsingularity.net> References: <20180627084954.73ucqvac62v5gje4@techsingularity.net> <20180717100329.yfy7igdsrpk5ujf4@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: 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 On Mon, Sep 03, 2018 at 05:07:15PM +0200, Jirka Hladky wrote: > Resending in the plain text mode. > > > My own testing completed and the results are within expectations and I > > saw no red flags. Unfortunately, I consider it unlikely they'll be merged > > for 4.18. Srikar Dronamraju's series is likely to need another update > > and I would need to rebase my patches on top of that. Given the scope > > and complexity, I find it unlikely they would be accepted for an -rc, > > particularly this late of an rc. Whether we hit the 4.19 merge window or > > not will depend on when Srikar's series gets updated. > > > Hi Mel, > > we have collaborated back in July on the scheduler patch, improving > the performance by allowing faster memory migration. You came up with > the "sched-numa-fast-crossnode-v1r12" series here: > > https://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git > > which has shown good performance results both in your and our testing. > I remember. > Do you have some update on the latest status? Is there any plan to > merge this series into 4.19 kernel? We have just tested 4.19.0-0.rc1.1 > and based on the results it seems that the patch is not included (and > I don't see it listed in git shortlog v4.18..v4.19-rc1 > ./kernel/sched) > Srikar's series that mine depended upon was only partially merged due to a review bottleneck. He posted a v2 but it was during the merge window and likely will need a v3 to avoid falling through the cracks. When it is merged, I'll rebase my series on top and post it. While I didn't check against 4.19-rc1, I did find that rebasing on top of the partial series in 4.18 did not have as big an improvement. > With 4.19rc1 we see performance drop > * up to 40% (NAS bench) relatively to 4.18 + sched-numa-fast-crossnode-v1r12 > * up to 20% (NAS, Stream, SPECjbb2005, SPECjvm2008) relatively to 4.18 vanilla > The performance is dropping. It's quite unclear what are the next > steps - should we wait for "sched-numa-fast-crossnode-v1r12" to be > merged or should we start looking at what has caused the drop in > performance going from 4.19rc1 to 4.18? > Both are valid options. If you take the latter option, I suggest looking at whether 2d4056fafa196e1ab4e7161bae4df76f9602d56d is the source of the issue as at least one auto-bisection found that it may be problematic. Whether it is an issue or not depends heavily on the number of threads relative to a socket size. -- Mel Gorman SUSE Labs