From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754191AbXD0MYr (ORCPT ); Fri, 27 Apr 2007 08:24:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755718AbXD0MYr (ORCPT ); Fri, 27 Apr 2007 08:24:47 -0400 Received: from isilmar.linta.de ([213.239.214.66]:42302 "EHLO linta.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754191AbXD0MYq (ORCPT ); Fri, 27 Apr 2007 08:24:46 -0400 Date: Fri, 27 Apr 2007 08:24:44 -0400 From: Dominik Brodowski To: Dave Jones , Nish Aravamudan , William Heimbigner , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [RFC] [PATCH] cpufreq: allow full selection of default governors Message-ID: <20070427122444.GA3714@isilmar.linta.de> Mail-Followup-To: Dominik Brodowski , Dave Jones , Nish Aravamudan , William Heimbigner , linux-kernel@vger.kernel.org, Andrew Morton References: <20070424211253.GG23598@redhat.com> <29495f1d0704241505p62140160o52d83e383106bf8e@mail.gmail.com> <20070425000327.GG22267@redhat.com> <20070427015410.GA9650@isilmar.linta.de> <20070427060957.GA4726@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070427060957.GA4726@redhat.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 27, 2007 at 02:09:57AM -0400, Dave Jones wrote: > On Thu, Apr 26, 2007 at 09:54:10PM -0400, Dominik Brodowski wrote: > > On Tue, Apr 24, 2007 at 08:03:27PM -0400, Dave Jones wrote: > > > On Tue, Apr 24, 2007 at 03:05:36PM -0700, Nish Aravamudan wrote: > > > > On 4/24/07, Dave Jones wrote: > > > > > On Tue, Apr 24, 2007 at 09:03:23PM +0000, William Heimbigner wrote: > > > > > > The following patches should allow selection of conservative, powersave, and > > > > > > ondemand in the kernel configuration. > > > > > > > > > > This has been rejected several times already. > > > > > Ondemand and conservative isn't a viable governor for all cpufreq > > > > > implementations (ie, ones with high switching latencies). > > > > > > > > This piques my curiosity -- some governors don't work with some > > > > cpufreq implementations. Are those implementations in the kernel or in > > > > userspace? If in the kernel, then perhaps there should be some > > > > dependency expressed there in Kconfig between cpufreq implementation > > > > and the available governors > > > > > > it can't be solved that easily. powernow-k8 for example is fine to > > > use with ondemand on newer systems, where the latency is low. > > > On older models however, it isn't. > > > > > > > > Also, see the > > > > > comment in the Kconfig a few lines above where you are adding this. > > > > > > > > Are these governors unfixable? If > > > > > > tbh, I've forgotten the original issues that caused the comment > > > to be placed there. Dominik ? > > > > Not unfixable, but: cpufreq is currently[*] built around the assumption that > > at least one governor is correctly initialized or can be brought to work > > when a CPU is registered with the cpufreq core. > > It would have to take something fairly spectacular though for performance or > powersave to fail registration. Can you remember why we chose not to allow those? performance _is_ allowed; powersave would be possible -- but then those who accidentally enable it on elanfreq might wait 100 times as long for the system to boot, with gx-suspmod it might even be 255 times as long -- okay, by default it's just 20 times as long, but still... Dominik