From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756883Ab2CHPWa (ORCPT ); Thu, 8 Mar 2012 10:22:30 -0500 Received: from wega.rz.tu-ilmenau.de ([141.24.4.159]:35779 "EHLO wega.rz.tu-ilmenau.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753764Ab2CHPW2 (ORCPT ); Thu, 8 Mar 2012 10:22:28 -0500 Message-ID: <4F58CE25.5070906@tu-ilmenau.de> Date: Thu, 08 Mar 2012 16:20:05 +0100 From: =?UTF-8?B?U3RlcGhhbiBCw6Ryd29sZg==?= Reply-To: stephan.baerwolf@tu-ilmenau.de Organization: TU-Ilmenau User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.1) Gecko/20120303 Thunderbird/10.0.1 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org CC: linaro-kernel@lists.linaro.org, panto@antoniou-consulting.com Subject: Re: [RFC] Scheduler recorder and playback References: <85A3EFC3-FAE0-4B3A-AAA0-85FA435A9F7B@antoniou-consulting.com> In-Reply-To: <85A3EFC3-FAE0-4B3A-AAA0-85FA435A9F7B@antoniou-consulting.com> X-Enigmail-Version: 1.3.5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pantelis, what is your primary goal? Saving power? Improving interactivity? Be more cache-optimal? I think recording the scheduling (without drastically slowing it down) is hard to do, since it ticks at least HZ times per second. Replay such an recording (on a differeny platform) seems even harder to me. Since different cpus (and number of them), different speed and a very likely not reproduceable process-setup may noise completely the replay. Do you also want to record/replay the behaviour of the more important loadbalancer, too? Did you thought to compare different platforms by simply having syntetically generated loads? (I.e. see interbench -> http://users.on.net/~ckolivas/interbench/) If you are interested in examing the scheduling-behaviour as a function of the tuneables (and even the HZ) - and if you are interested in getting better latency, maybe you are interested in nitro-patch for the scheduler? (I currently don't have an external patch-file, but you can get it integrated from https://github.com/baerwolf/linux-stephan/commits/v3.2.9-stephan-201203030000 ) Nitro enables you to do so some things, like: * tune the scheduler at configuration point * increase the ticker-frequency way above 1000Hz * tune the ticker-freq. from userspace during runtime * change the scheduling-algo for idle-tasks regards Stephan