From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Scott Thompson" Subject: Metrics for comparing power savings of patches... Date: Fri, 07 Mar 2008 12:01:05 -0500 Message-ID: <20080307170105.AF99E1A0039@mailserver8.hushmail.com> Reply-To: postfail@hushmail.com Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: 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: linux-pm@lists.linux-foundation.org, power@bughost.org List-Id: linux-pm@vger.kernel.org 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. 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. --------------------------------------- Scott Thompson / postfail@hushmail.com ---------------------------------------