From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754463AbZHYGZE (ORCPT ); Tue, 25 Aug 2009 02:25:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752792AbZHYGZB (ORCPT ); Tue, 25 Aug 2009 02:25:01 -0400 Received: from sg2ehsobe005.messaging.microsoft.com ([207.46.51.79]:34279 "EHLO SG2EHSOBE005.bigfish.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751205AbZHYGZA convert rfc822-to-8bit (ORCPT ); Tue, 25 Aug 2009 02:25:00 -0400 X-SpamScore: -2 X-BigFish: VPS-2(z1857r34a4j8deiz1432R98dN936eM13f4ja594izz1202hzzz32i6bh203h43j61h) X-Spam-TCS-SCL: 0:0 X-WSS-ID: 0KOX5TA-01-BNI-02 X-M-MSG: Date: Tue, 25 Aug 2009 08:24:32 +0200 From: Andreas Herrmann To: Peter Zijlstra CC: Ingo Molnar , linux-kernel@vger.kernel.org, Gautham Shenoy , Srivatsa Vaddagiri , Dipankar Sarma , Balbir Singh , "svaidy@linux.vnet.ibm.com" , Arun R Bharadwaj Subject: Re: [PATCH 8/15] sched: Add parameter sched_mn_power_savings to control MN domain sched policy Message-ID: <20090825062432.GB20811@alberich.amd.com> References: <20090820131243.GO29327@alberich.amd.com> <20090820133914.GW29327@alberich.amd.com> <1251125778.7538.268.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Disposition: inline In-Reply-To: <1251125778.7538.268.camel@twins> User-Agent: Mutt/1.5.16 (2007-06-09) X-OriginalArrivalTime: 25 Aug 2009 06:24:33.0285 (UTC) FILETIME=[B5E42350:01CA254C] Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 24, 2009 at 04:56:18PM +0200, Peter Zijlstra wrote: > On Thu, 2009-08-20 at 15:39 +0200, Andreas Herrmann wrote: > > Signed-off-by: Andreas Herrmann > > --- > > > +#ifdef CONFIG_SCHED_MN > > + if (!err && mc_capable()) > > + err = sysfs_create_file(&cls->kset.kobj, > > + &attr_sched_mn_power_savings.attr); > > +#endif > > *sigh* another crappy sysfs file > > Guys, can't we come up with anything better than sched_*_power_saving=n? Thought this is a settled thing. At least there are already two such parameters. So using the existing convention is an obvious thing, no? > This configuration space is _way_ too large, and now it gets even > crazier. I don't fully agree. Having one control interface for each domain level is just one approach. It gives the user full control of scheduling policies. It just might have to be properly documented. In another mail Vaidy mentioned that "at some point we wanted to change the interface to sched_power_savings=N and and set the flags according to system topology". But how you'll decide at which domain level you have to do power savings scheduling? Using sched_mn_power_savings=1 is quite different from sched_smt_power_savings=1. Probably, the most power you save if you switch on power saving scheduling on each domain level. I.e. first filling threads of one core, then filling all cores on one internal node, then filling all internal nodes of one socket. But for performance reasons a user might just want to use power savings in the MN domain. How you'd allow the user to configure that with just one interface? Passing the domain level to sched_power_savings, e.g. sched_power_savings=MC instead of the power saving level? Besides that, don't we have to keep the user-interface stable, i.e. stick to sched_smt_power_savings and sched_mc_power_savings? Regards, Andreas -- Operating | Advanced Micro Devices GmbH System | Karl-Hammerschmidt-Str. 34, 85609 Dornach b. München, Germany Research | Geschäftsführer: Thomas M. McCoy, Giuliano Meroni Center | Sitz: Dornach, Gemeinde Aschheim, Landkreis München (OSRC) | Registergericht München, HRB Nr. 43632