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[23.128.96.18]) by mx.google.com with ESMTP id d71si15894485pgc.417.2021.09.27.08.05.30; Mon, 27 Sep 2021 08:06:01 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234865AbhI0PEW (ORCPT + 99 others); Mon, 27 Sep 2021 11:04:22 -0400 Received: from outbound-smtp35.blacknight.com ([46.22.139.218]:41989 "EHLO outbound-smtp35.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234816AbhI0PEV (ORCPT ); Mon, 27 Sep 2021 11:04:21 -0400 Received: from mail.blacknight.com (pemlinmail05.blacknight.ie [81.17.254.26]) by outbound-smtp35.blacknight.com (Postfix) with ESMTPS id 6AE061B9D for ; Mon, 27 Sep 2021 16:02:42 +0100 (IST) Received: (qmail 12030 invoked from network); 27 Sep 2021 15:02:42 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.17.29]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 27 Sep 2021 15:02:42 -0000 Date: Mon, 27 Sep 2021 16:02:40 +0100 From: Mel Gorman To: Vincent Guittot Cc: Mike Galbraith , Peter Zijlstra , Ingo Molnar , Valentin Schneider , Aubrey Li , Barry Song , Srikar Dronamraju , LKML Subject: Re: [PATCH 2/2] sched/fair: Scale wakeup granularity relative to nr_running Message-ID: <20210927150240.GI3959@techsingularity.net> References: <20210922150457.GA3959@techsingularity.net> <20210922173853.GB3959@techsingularity.net> <50400427070018eff83b0782d2e26c0cc9ff4521.camel@gmx.de> <20210927111730.GG3959@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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 27, 2021 at 04:19:00PM +0200, Vincent Guittot wrote: > On Mon, 27 Sept 2021 at 13:17, Mel Gorman wrote: > > > > On Thu, Sep 23, 2021 at 02:41:06PM +0200, Vincent Guittot wrote: > > > On Thu, 23 Sept 2021 at 11:22, Mike Galbraith wrote: > > > > > > > > On Thu, 2021-09-23 at 10:40 +0200, Vincent Guittot wrote: > > > > > > > > > > a 100us value should even be enough to fix Mel's problem without > > > > > impacting common wakeup preemption cases. > > > > > > > > It'd be nice if it turn out to be something that simple, but color me > > > > skeptical. I've tried various preemption throttling schemes, and while > > > > > > Let's see what the results will show. I tend to agree that this will > > > not be enough to cover all use cases and I don't see any other way to > > > cover all cases than getting some inputs from the threads about their > > > latency fairness which bring us back to some kind of latency niceness > > > value > > > > > > > Unfortunately, I didn't get a complete set of results but enough to work > > with. The missing tests have been requeued. The figures below are based > > on a single-socket Skylake machine with 8 CPUs as it had the most set of > > results and is the basic case. > > > > The reported kernels are > > > > vanilla: vanilla 5.15-rc1 > > sched-scalewakegran-v2r4: My patch > > sched-moveforward-v1r1: Vincent's patch > > I imagine that this is the results for the 1st version which scales > with the number of CPUs > Yes, the v1r5 results were incomplete and had to be requeued. -- Mel Gorman SUSE Labs