From mboxrd@z Thu Jan 1 00:00:00 1970 From: Todd Poynor Subject: Re: [PATCHSET] 0/3 Dynamic cpufreq governor and updates to ACPI P-state driver Date: Thu, 23 Oct 2003 11:16:48 -0700 Sender: cpufreq-bounces@www.linux.org.uk Message-ID: <3F981B10.3070900@mvista.com> References: <88056F38E9E48644A0F562A38C64FB6007793C@scsmsx403.sc.intel.com> <1066897184.395.1.camel@laptop.fenrus.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------090405070502060008070407" Return-path: In-Reply-To: <1066897184.395.1.camel@laptop.fenrus.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: cpufreq-bounces@www.linux.org.uk To: arjanv@redhat.com Cc: linux-acpilinux-acpi@intel.com, cpufreq@www.linux.org.uk, "Pallipadi, Venkatesh" This is a multi-part message in MIME format. --------------090405070502060008070407 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit On Wed, 2003-10-22 at 20:21, Pallipadi, Venkatesh wrote: >And with the kind of power savings that comes with these frequency >changes, this behaviour >results in longer battery life. However, as yet I do not have any >numbers to quantify this gain, >mainly because I do not have any setup where I can measure actual power. I measured amps consumed by a 1.4GHz Centrino notebook model running a similar power management system called Dynamic Power Management http://dynamicpower.sourceforge.net, which leverages code from the speedstep-centrino cpufreq driver by Jeremy Fitzhardinge. DPM is set to run the system at full power when running a process and at minimal power when idle (using scheduler hooks). These numbers, which are attached, would probably roughly correspond to a cpufreq-based setup on the same platform that modified the CPU speed and voltage very quickly in response to process scheduling activity. I may perform some analysis of more dynamic applications that more evenly divide their time between active and idle in the near future, in case there is any interest in this. Amps consumed should be a good predictor of expected battery life, independent of the vagaries of any particular battery. The expensive scopemeter used for the attached measurements isn't really necessary, by the way; a $130 multimeter that averages DC amps, placed in series between the DC transformer and the notebook, should do fine. In case this helps, -- Todd --------------090405070502060008070407 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Cpufreq mailing list Cpufreq@www.linux.org.uk http://www.linux.org.uk/mailman/listinfo/cpufreq --------------090405070502060008070407--