From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philipp Miedl Subject: Re: Delayed acpi frequency governor call Date: Wed, 25 Jan 2017 10:48:40 +0100 Message-ID: <47c8a3d0-c871-c211-f951-2b6607310cff@tik.ee.ethz.ch> References: <20170120100725.GO11478@vireshk-i7> <9b332b49-11a1-a5fc-d48e-2c113cdca202@tik.ee.ethz.ch> <20170123101145.GB26681@vireshk-i7> <086bc55f-d1cc-b893-49c6-1667f6067f1b@tik.ee.ethz.ch> <20170124042235.GA16906@vireshk-i7> <2f9b2f69-8b93-c77a-a09f-540240fecf1e@tik.ee.ethz.ch> <20170125032341.GC20040@vireshk-i7> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from virgo01.ee.ethz.ch ([129.132.2.226]:41021 "EHLO virgo01.ee.ethz.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751679AbdAYJso (ORCPT ); Wed, 25 Jan 2017 04:48:44 -0500 In-Reply-To: <20170125032341.GC20040@vireshk-i7> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: alex@digriz.org.uk, jun.nakajima@intel.com, "linux-pm@vger.kernel.org" On 25.01.2017 04:23, Viresh Kumar wrote: > On 24-01-17, 15:49, Philipp Miedl wrote: >> Can you please describe how things changed from version 4.4 to 4.9 - I'm not >> sure if I understand correctly. >> Before 4.7 the governor was just running as a kernel process and triggered >> by the (free running) timers and >> now its hooked with the scheduler. So the scheduler ensures that the >> governor work is not delayed?! > Now the cpufreq callbacks gets called from within the scheduler every few > milliseconds. And once we have crossed the sampling-rate time, we reevaluate the > frequency. Though ondemand/conservative governors still used workqueue until > very recently for most of the platforms. Recently it is replaced by a RT thread. > Ok got it now. Thanks a lot for your help! -- -------------------------------------------------------------------- | Philipp Miedl | | PhD Student @ Computer Engineering and Networks Laboratory | | ETH Zurich, ETZG76, Gloriastrasse 35, 8092 Zurich, Switzerland | | mail: philipp.miedl@ee.tik.ethz.ch phone: +41 44 632 70 61 | --------------------------------------------------------------------