Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932225AbZDBLNB (ORCPT ); Thu, 2 Apr 2009 07:13:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762204AbZDBLMv (ORCPT ); Thu, 2 Apr 2009 07:12:51 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:50926 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753979AbZDBLMu (ORCPT ); Thu, 2 Apr 2009 07:12:50 -0400 Subject: Re: [RFC] Improving scheduler for asymmetric multi-core processor in Google's summer of code From: Peter Zijlstra To: Hitoshi Mitake Cc: linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org In-Reply-To: References: Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Thu, 02 Apr 2009 13:13:46 +0200 Message-Id: <1238670826.8530.5837.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1440 Lines: 39 On Wed, 2009-04-01 at 23:58 +0900, Hitoshi Mitake wrote: > Hi, > > I found an interesting problem, scheduling on Asymmetric multi-core processor. > > According to this paper, > > http://portal.acm.org/citation.cfm?id=1362694&dl=GUIDE&coll=GUIDE&CFID=28487975&CFTOKEN=68150071 > > taking performance asymmetry into consideration on multi-core CPUs can > improve scheduler performance. > (And I think discarding this could have bad consequences.) > > So I have a question: > Is the current scheduler of Linux aware of possible performance > asymmetry of the cores? It does not. > By performance asymmetry I mean a case where different cores run on > different frequencies. > > If something tackling this issue is not implemented yet, > I would like to work on that as a project of Google's summer of code. Have at it. Its a rather delicate business though and should also include scaling balancing decisions based on time taken by IRQs and RT tasks as well as incorporate feedback from the cpu. The latter includes things like cpufreq, but also effective work done by threads on a core. Its been on my todo list for quite a while, but haven't managed to get something robust together. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/