From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753859Ab1JKJHX (ORCPT ); Tue, 11 Oct 2011 05:07:23 -0400 Received: from casper.infradead.org ([85.118.1.10]:39258 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752327Ab1JKJHS (ORCPT ); Tue, 11 Oct 2011 05:07:18 -0400 Subject: Re: sched: ARM: arch_scale_freq_power From: Peter Zijlstra To: Vincent Guittot Cc: Amit Kucheria , linux-kernel@vger.kernel.org, LAK , linaro-dev@lists.linaro.org In-Reply-To: References: <1318319852.14400.65.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Tue, 11 Oct 2011 11:13:19 +0200 Message-ID: <1318324399.14400.71.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-10-11 at 10:51 +0200, Vincent Guittot wrote: > I have several goals. The 1st one is that I need to put more load on > some cpus when I have packages with different cpu frequency. That should be rather easy. > I also study if I can follow the real cpu frequency but it seems to be > not so easy. Why not? > I have noticed that the cpu_power is updated periodical > except when we have a lot of newly_idle events. We can certainly fix that. > Then, I have some use cases which have several running tasks but a low > cpu load. In this case, the small tasks are spread on several cpu by > the load_balance whereas they could be easily handled by one cpu > without significant performance modification. That shouldn't be done using cpu_power, we have sched_smt_power_savings and sched_mc_power_savings for stuff like that. Although I would really like to kill all those different sched_*_power_savings knobs and reduce it to one. > If the cpu_power is > higher than 1024, the cpu is no more seen out of capacity by the > load_balance as soon as a short process is running and teh main result > is that the small tasks will stay on the same cpu. This configuration > is mainly usefull for ARM dual core system when we want to power gate > one cpu. I use cyclictest to simulate such use case. Yeah, but that's wrong.