From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: Metrics for comparing power savings of patches... Date: Sun, 16 Mar 2008 20:03:42 +0100 Message-ID: <20080316190341.GA4638@ucw.cz> References: <20080307170105.AF99E1A0039@mailserver8.hushmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20080307170105.AF99E1A0039@mailserver8.hushmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Scott Thompson Cc: linux-pm@lists.linux-foundation.org, power@bughost.org List-Id: linux-pm@vger.kernel.org On Fri 2008-03-07 12:01:05, Scott Thompson wrote: > I've seen several patch submissions and comments with varying > claims of 'power savings' from one level to another on both the > linux-pm and powertop lists. > > Standard technique seems to be to plug computer directly into a > wattmeter and then provide some feedback as to the savings comparing > one patchgroup to what is currently available. > > Different wattmeters, however, will have different response and > accuracy depending on load for instant readings; usually the lower- > loads (such as laptops) will be less accurate. notebooks usually have internal wattmeters. cat /proc/acpi/batt*/*/*. > However, I have seen that most wattmeters do a 'better' job at > measuring total wattage over an interval than the 'instant > reading'. I advise caution in advertising 'expected savings' for > instant readings.... > > Also, if anyone knows of any free benchmarks, best practices, or > guidelines for trying to do comparative power analysis for patches > with wattmeters please let me know. Intel has something on lesswatts.org. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html