Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751986AbcJJKBQ (ORCPT ); Mon, 10 Oct 2016 06:01:16 -0400 Received: from mail-qt0-f170.google.com ([209.85.216.170]:33930 "EHLO mail-qt0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751697AbcJJKBO (ORCPT ); Mon, 10 Oct 2016 06:01:14 -0400 Date: Mon, 10 Oct 2016 11:01:07 +0100 From: Matt Fleming To: Wanpeng Li Cc: Peter Zijlstra , Ingo Molnar , "linux-kernel@vger.kernel.org" , Mike Galbraith , Yuyang Du , Vincent Guittot , Dietmar Eggemann Subject: Re: [PATCH] sched/fair: Do not decay new task load on first enqueue Message-ID: <20161010100107.GZ16071@codeblueprint.co.uk> References: <20160923115808.2330-1-matt@codeblueprint.co.uk> <20160928101422.GR5016@twins.programming.kicks-ass.net> <20160928193731.GD16071@codeblueprint.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24+41 (02bc14ed1569) (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 993 Lines: 24 On Sun, 09 Oct, at 11:39:27AM, Wanpeng Li wrote: > > The difference between this patch and Peterz's is your patch have a > delta since activate_task()->enqueue_task() does do update_rq_clock(), > so why don't have the delta will cause low cpu machines (4 or 8) to > regress against your another reply in this thread? Both my patch and Peter's patch cause issues with low cpu machines. In <20161004201105.GP16071@codeblueprint.co.uk> I said, "This patch causes some low cpu machines (4 or 8) to regress. It turns out they regress with my patch too." Have I misunderstood your question? I ran out of time to investigate this last week, though I did try all proposed patches, including Vincent's, and none of them produced wins across the board. I should get a bit further this week. Vincent, Dietmar, did you guys ever get around to submitting your PELT tracepoint patches? Getting some introspection into the scheduler's load balancing decisions would speed up this sort of research.