From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lukasz Majewski Subject: Re: [PATCH v3 1/3] cpufreq: Add boost frequency support in core Date: Tue, 18 Jun 2013 11:12:36 +0200 Message-ID: <20130618111236.614d43a0@amdc308.digital.local> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1371195540-2991-1-git-send-email-l.majewski@samsung.com> <1371195540-2991-2-git-send-email-l.majewski@samsung.com> <20130617091549.398b865f@amdc308.digital.local> <20130617110811.1e1805d2@amdc308.digital.local> <20130617115809.5206c42c@amdc308.digital.local> <20130617155156.4c729b5a@amdc308.digital.local> <20130618102429.5ff68931@amdc308.digital.local> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mailout1.samsung.com ([203.254.224.24]:13111 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755547Ab3FRJNM (ORCPT ); Tue, 18 Jun 2013 05:13:12 -0400 In-reply-to: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: "Rafael J. Wysocky" , "cpufreq@vger.kernel.org" , Linux PM list , Vincent Guittot , Jonghwa Lee , Myungjoo Ham , linux-kernel , Lukasz Majewski , Andre Przywara , Daniel Lezcano , Kukjin Kim , Amit Daniel Kachhap On Tue, 18 Jun 2013 14:10:28 +0530, Viresh Kumar wrote: > On 18 June 2013 13:54, Lukasz Majewski wrote: > > On Tue, 18 Jun 2013 08:42:13 +0200, Viresh Kumar wrote: > > >> Its not about how long.. One cpu type can work longer with boost > >> freq compared to other. > >> > >> What we probably need is: > >> - Enabled boost from sysfs if required (now below steps will come > >> into picture) > >> - See how many cpus are running, if only one then start using boost > >> freqs > > > > You are right here. > > > > I'd like to propose following solution: > > 1. For acpi (where boost_enable come into play) - do not consider > > number of active cpus (this is done in HW anyway) > > > > 2. For SW solution evaluate how many CPUs are running. If only one > > is running then allow enabling boost from sysfs. > > Looks fine. Ok, > > > But following situation is also possible: User enable boost when one > > core is only running and then for some reason other core is woken > > up. What shall be done then? > > Shall we then disable boost immediately when cpufreq detects that > > more than one core is running? Or leave this situation to be > > handled by thermal subsystem? > > Obviously disable boost ASAP. Every SoC might not have a thermal > framework glue to do it. Implementation of counting number of idle CPUs would impose extending the cpufreq core itself. Do you have any hints how this can be done in a neat way? I suspect, that porting the LAB solution to the cpufreq core may be not easy. I think that the best place for it would be governor core code. > > > As a side note: > > Logic proposed at point 2, is already implemented at LAB > > (enable LAB only when one core is running and disable it when more > > than one come into play). > > Hmm.. So, eventually that will go away now :) But this is not the only functionality, which LAB posses :-). > > >> - Now thermal should be come into picture to save chip in case a > >> single cpu running at boost can burn it out. > > > > I will extent v4 to embrace code which switches off boost at > > thermal. > > Gud. Ok. -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group