Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751546AbcDTWYV (ORCPT ); Wed, 20 Apr 2016 18:24:21 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:33068 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751184AbcDTWYT (ORCPT ); Wed, 20 Apr 2016 18:24:19 -0400 MIME-Version: 1.0 In-Reply-To: <20160420140117.GZ3448@twins.programming.kicks-ass.net> References: <1460958684-32105-1-git-send-email-wanpeng.li@hotmail.com> <6087716.bi8vDPiZNy@vostro.rjw.lan> <20160420140117.GZ3448@twins.programming.kicks-ass.net> Date: Thu, 21 Apr 2016 06:24:18 +0800 Message-ID: Subject: Re: [PATCH] sched/cpufreq: don't trigger cpufreq update w/o real rt/deadline tasks running From: Wanpeng Li To: Peter Zijlstra Cc: "Rafael J. Wysocki" , Ingo Molnar , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , Wanpeng Li , Linux PM list , Steve Muckle Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1100 Lines: 30 2016-04-20 22:01 GMT+08:00 Peter Zijlstra : > On Wed, Apr 20, 2016 at 02:32:35AM +0200, Rafael J. Wysocki wrote: >> On Monday, April 18, 2016 01:51:24 PM Wanpeng Li wrote: >> > Sometimes update_curr() is called w/o tasks actually running, it is >> > captured by: >> > u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start; >> > We should not trigger cpufreq update in this case for rt/deadline >> > classes, and this patch fix it. >> > >> > Signed-off-by: Wanpeng Li >> >> The signed-off-by tag should agree with the From: header. One way to achieve >> that is to add an extra From: line at the start of the changelog. >> >> That said, this looks like a good catch that should go into 4.6 to me. >> >> Peter, what do you think? > > I'm confused by the Changelog. *what* ? Sometimes .update_curr hook is called w/o tasks actually running, it is captured by: u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start; We should not trigger cpufreq update in this case for rt/deadline classes, and this patch fix it. Regards, Wanpeng Li