From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH] cpufreq: ondemand: Change the calculation of target frequency Date: Mon, 3 Jun 2013 16:54:08 +0530 Message-ID: References: <51A7BFA6.3070800@semaphore.gr> <2413427.Abjbfkms0Z@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <2413427.Abjbfkms0Z@vostro.rjw.lan> Sender: cpufreq-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: Stratos Karafotis , linux-kernel@vger.kernel.org, cpufreq@vger.kernel.org, linux-pm@vger.kernel.org List-Id: linux-pm@vger.kernel.org On 3 June 2013 16:27, Rafael J. Wysocki wrote: > The question is if we want policy->max to re-scale them effectively (i.e. to > change weights so that the maximum load maps to the highest frequency available > at the moment) or if we want policy->max to work as a cap (i.e. to map all > loads above certain value to the maximum frequency available at the moment, so > that the criteria for selecting the lower frequencies don't change). In my > opinion the second option is better, because it means "OK, we can't use some > high frequencies, but let's not hurt performance for the loads that wouldn't > require them anyway". Otherwise, we'll effectively throttle all loads and > that not only causes performance to drop, but also causes more energy to be > used overall. I wouldn't say that I don't agree with you as I do to some extent. But the question that comes to my mind now is: Why is policy->max reduced in the first place? User doesn't have control over which freqs to expose, so available_frequencies will stay the same. The only thing he is capable of doing is: reduce policy->max.. Which in a way means that.. "I don't want to use higher frequencies (power, thermal reasons) and I know performance will go down with it and I don't care for it now." And this way I feel policy->max isn't a bad choice either. BUT as you said: policy->max isn't there to say don't be so aggressive now in increasing frequencies but just only to say, don't go over this frequency.. So, probably we can use cpuinfo.max_freq :)