From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============7387269889867516975==" MIME-Version: 1.0 From: Ivan Shapovalov Subject: Re: [Powertop] [powertop] ::wiggle() - what does that do? Date: Wed, 20 Mar 2013 00:00:08 +0400 Message-ID: <2252008.4yp4TNWOLD@intelfx-laptop> In-Reply-To: 5148C379.7000002@linux.intel.com To: powertop@lists.01.org List-ID: --===============7387269889867516975== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On 19 March 2013 12:58:49 Arjan van de Ven wrote: > On 3/19/2013 12:57 PM, Ivan Shapovalov wrote: > > On 19 March 2013 12:53:26 Arjan van de Ven wrote: > >> On 3/19/2013 12:51 PM, Ivan Shapovalov wrote: > >>> Hello all, > >>> = > >>> I've been wondering on what does the abstract_cpu::wiggle() function > >>> does > >>> and why it is needed?.. All the code says is that it is needed to "ha= ve > >>> a > >>> record of CPU at the start and end of the perf trace". > >>> = > >>> I'm asking just because I feel somewhat uncomfortable to have powertop > >>> changing my scaling frequency back and forth each N seconds. :) > >> = > >> the reason this exists is that powertop wants to track what frequency = the > >> cpu is at for the duration... ... and there's no way to ask for > >> "current", > >> only to get change notifications > >> = > >> so wiggle() forces a change... and from then on we know what it's at. > > = > > ...And why isn't it possible to keep the value from last notification? > = > there may not have been one... > = > > Because time can pass between measurement end and new measurement start? > = > yep Thanks. It's clear to me now. --===============7387269889867516975==--