From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: Delayed acpi frequency governor call Date: Wed, 25 Jan 2017 08:53:41 +0530 Message-ID: <20170125032341.GC20040@vireshk-i7> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pf0-f179.google.com ([209.85.192.179]:36062 "EHLO mail-pf0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751150AbdAYDXp (ORCPT ); Tue, 24 Jan 2017 22:23:45 -0500 Received: by mail-pf0-f179.google.com with SMTP id 189so54771853pfu.3 for ; Tue, 24 Jan 2017 19:23:45 -0800 (PST) Content-Disposition: inline In-Reply-To: <2f9b2f69-8b93-c77a-a09f-540240fecf1e@tik.ee.ethz.ch> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Philipp Miedl Cc: alex@digriz.org.uk, jun.nakajima@intel.com, "linux-pm@vger.kernel.org" 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. -- viresh