From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mel Gorman Subject: Re: [4.17 regression] Performance drop on kernel-4.17 visible on Stream, Linpack and NAS parallel benchmarks Date: Thu, 6 Sep 2018 13:58:43 +0100 Message-ID: <20180906125843.GC1719@techsingularity.net> References: <20180717100329.yfy7igdsrpk5ujf4@techsingularity.net> <20180904090053.GB1719@techsingularity.net> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Jirka Hladky Cc: Kamil Kolakowski , Jakub Racek , linux-kernel , "Rafael J. Wysocki" , Len Brown , linux-acpi@vger.kernel.org List-Id: linux-acpi@vger.kernel.org On Thu, Sep 06, 2018 at 10:16:28AM +0200, Jirka Hladky wrote: > Hi Mel, > > we have results with 2d4056fafa196e1ab4e7161bae4df76f9602d56d reverted. > > * Compared to 4.18, there is still performance regression - > especially with NAS (sp_C_x subtest) and SPECjvm2008. On 4 NUMA > systems, regression is around 10-15% > * Compared to 4.19rc1 there is a clear gain across all benchmarks around 20% > Ok. > While reverting 2d4056fafa196e1ab4e7161bae4df76f9602d56d has helped a > lot there is another issue as well. Could you please recommend some > commit prior to 2d4056fafa196e1ab4e7161bae4df76f9602d56d to try? > Maybe 305c1fac3225dfa7eeb89bfe91b7335a6edd5172. That introduces a weird condition in terms of idle CPU handling that has been problematic. > Regarding the current results, how do we proceed? Could you please > contact Srikar and ask for the advice or should we contact him > directly? > I would suggest contacting Srikar directly. While I'm working on a series that touches off some similar areas, there is no guarantee it'll be a success as I'm not primarily upstream focused at the moment. Restarting the thread would also end up with a much more sensible cc list. -- Mel Gorman SUSE Labs