From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philipp Miedl Subject: Re: Delayed acpi frequency governor call Date: Tue, 24 Jan 2017 15:49:51 +0100 Message-ID: <2f9b2f69-8b93-c77a-a09f-540240fecf1e@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> 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]:55792 "EHLO virgo01.ee.ethz.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750847AbdAXOt4 (ORCPT ); Tue, 24 Jan 2017 09:49:56 -0500 In-Reply-To: <20170124042235.GA16906@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" > You are using a 4.4 kernel, which used the older delayed work stuff at sampling > rate. This has all changed a lot and we hooks paired with the scheduler now to > do this instead. Things have mostly changed since 4.7. Would it be possible for > you to use a later kernel and see if you still see something wrong? I switched to the latest stable kernel available, 4.9.5. Judging from the first test I ran, using this kernel I cannot reproduce this behavior anymore. Looks like it has been fixed by the changes introduced. > Now coming back to 4.4, the timers (in the delayed works) can't get delayed but > the work can as it is just another process. 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?! > But your setup has no almost load > and that seems unlikely as well. So, it looks to be a problem at some other > place. Tracers are your friend, only those can confirm something here. Thanks for the tip with the tracers. If time allows I will have a look into that - I would like to know whats going on, just out of curiosity. -- -------------------------------------------------------------------- | 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 | --------------------------------------------------------------------