Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754537Ab3F1Dun (ORCPT ); Thu, 27 Jun 2013 23:50:43 -0400 Received: from mail-oa0-f44.google.com ([209.85.219.44]:48544 "EHLO mail-oa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754210Ab3F1Duk (ORCPT ); Thu, 27 Jun 2013 23:50:40 -0400 MIME-Version: 1.0 In-Reply-To: <20130627164204.370dc4a6@amdc308.digital.local> References: <1370502472-7249-1-git-send-email-l.majewski@samsung.com> <1371661969-7660-1-git-send-email-l.majewski@samsung.com> <1371661969-7660-6-git-send-email-l.majewski@samsung.com> <20130627125819.5c90da30@amdc308.digital.local> <20130627164204.370dc4a6@amdc308.digital.local> Date: Fri, 28 Jun 2013 09:20:40 +0530 Message-ID: Subject: Re: [PATCH v4 5/7] cpufreq: Calculate number of busy CPUs From: Viresh Kumar To: Lukasz Majewski 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 , Zhang Rui , Eduardo Valentin Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2285 Lines: 60 On 27 June 2013 20:12, Lukasz Majewski wrote: > On Thu, 27 Jun 2013 16:46:44 +0530, Viresh Kumar wrote: >> @Rafael: We need you to jump into this discussion now, I don't >> have a good idea about what we should do :) >> >> On 27 June 2013 16:28, Lukasz Majewski wrote: >> > Do you have any idea of how to precisely set the load threshold? >> >> I thought we are talking about cpu being in idle state. > > If we _drop_ the idea with thermal subsystem to disable the boost, > the logic as far as I've understood shall here be as follow: > > Only enable BOOST when one CPU load > THRESHOLD_MAX and other CPUs < > THRESHOLD_MIN Again, I thought that we are talking about cpus being completely idle. i.e. in WFI (wait for interrupt) or deeper states. > THRESHOLD_MIN & THRESHOLD_MAX are SoC specific. > > In my opinion the above constrain imposes policy to the cpufreq driver. Hmm. > So thermal or "other solution" [*] shall disable boost when overheated > and enable it back when things cool down. yeah.. > [*] @ Viresh & Rafael do you have any idea about the "other solution" > here? Not really sure :) >> There might be platforms where overheating isn't a issue with boost, >> if it is only enabled while only one cpu is in use. > > Could you elaborate more on this? I meant platforms where chip doesn't heat up much when only one core is in use and is using boost frequency. So, they may not require support for thermal layer at all.. But I am not aware of what the ground reality is. If such systems can be possible or not. > This would prevent situation when somebody made a mistake and > had enabled boost, but for some reason had forgotten to > configure/enable thermal subsystem. > > Moreover Kconfig's CONFIG_CPUFREQ_BOOST flag would indicate that user > enabled boost for some reason and he/she (presumably) knows what is > doing. Yeah.. And drivers like ACPI cpufreq and exynos can simply do a select from their Kconfig entries so that user isn't required to select them. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/