From mboxrd@z Thu Jan 1 00:00:00 1970 From: Len Brown Subject: Re: About p4-clockmod breakage/removal Date: Wed, 14 May 2008 13:22:26 -0400 Message-ID: <200805141322.26879.lenb@kernel.org> References: <48246C3E.7010608@ceibo.fiec.espol.edu.ec> <20080514005636.GA21608@srcf.ucam.org> <20080514111817.GA21186@tangens.sinus.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:35853 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753150AbYENWmi (ORCPT ); Wed, 14 May 2008 18:42:38 -0400 In-Reply-To: <20080514111817.GA21186@tangens.sinus.cz> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Pavel Troller Cc: Matthew Garrett , cpufreq@lists.linux.org.uk, Alex =?iso-8859-1?q?Villac=ED=ADs_Lasso?= , linux-acpi@vger.kernel.org On Wednesday 14 May 2008, Pavel Troller wrote: > > On Tue, May 13, 2008 at 08:48:00PM -0400, Len Brown wrote: > > > > > Assuming this is a laptop with a batter, > > > I'd certainly be interested if you could run BLTK > > > and measure any benefit to p4-clockmod (I've never > > > been able to) > > > > The most plausible benefit to p4-clockmod is its utility in throttling > > the CPU if it would otherwise cause the system to overheat. From that > > point of view, I think it's worth keeping around - especially since not > > all machines expose T states via ACPI. > > > Hi! > I heavily used p4-clockmod having old, broken battery. Using it and > throttling the CPU frequency immediately after AC disconnection was > necessary to limit the maximum current the CPU was able to drain from > the battery. Otherwise, the battery voltage would drop below the allowed > level and the machine would either switch off or crash. Yes, in idle state, > there was no change in the CPU power consumption, but during heavy CPU > load, 75% throttle really limited the power consumption to the level > allowing operation even with that old poor battery. > So, p4-clockmod REALLY helped me a lot in this case. I vote for keeping > it on its place! > With regards, Pavel Troller Yes, we could design Linux to be optimal for this broken hardware. But the cost is that others with actual working hardware unnwittingly run p4-clockmod and slow down their machine with no energy savings benefit. Perhaps there is a different workaround (besides purchasing a battery or running on AC) that will help you? Does this machine export /proc/acpi/processor/*/throttling? -Len