Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755576Ab0D0NBy (ORCPT ); Tue, 27 Apr 2010 09:01:54 -0400 Received: from ksp.mff.cuni.cz ([195.113.26.206]:37134 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754912Ab0D0NBt (ORCPT ); Tue, 27 Apr 2010 09:01:49 -0400 Date: Tue, 27 Apr 2010 15:01:39 +0200 From: Pavel Machek To: Mike Chan Cc: Thomas Renninger , Arjan van de Ven , ?ric Piel , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, mingo@elte.hu, peterz@infradead.org, tglx@linutronix.de, davej@redhat.com, cpufreq@vger.kernel.org Subject: Re: [PATCH 7/7] ondemand: Solve the big performance issue with ondemand during disk IO Message-ID: <20100427130139.GC3681@ucw.cz> References: <20100418115949.7b743898@infradead.org> <4BCC147B.10708@tremplin-utc.net> <20100419064325.49cb3108@infradead.org> <201004201124.00326.trenn@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1242 Lines: 34 Hi! > > But I follow Eric and agree that if it costs that much, changing > > above sounds sane. > > Still, I could imagine some people might want to not raise freq on IO bound > > process activity, therefore this should get another ondemand param, similar > > to ignore_nice_load. > > > > I agree with Thomas here. Some of these assumptions on IO / FSB > performance with cpu speed do not hold true on various ARM platforms. > > Perhaps we could have a min_io_freq value? Which is the min speed for > the cpu to run at for IO bound activity. In the original patch, > min_io_freq = scaling_max_freq. For various arm devices I can happily > set min_io_freq to the lowest cpu speed that satisfies bus speeds. 'satisfies bus speeds' == minimum cpu frequency where i/o works at all or == minimum cpu frequency where i/o works at full speed ? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/