Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751384AbbG1Xve (ORCPT ); Tue, 28 Jul 2015 19:51:34 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:41289 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750827AbbG1Xvd convert rfc822-to-8bit (ORCPT ); Tue, 28 Jul 2015 19:51:33 -0400 From: "Rafael J. Wysocki" To: Pan Xinhui Cc: Viresh Kumar , "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" , "mnipxh@163.com" , "yanmin_zhang@linux.intel.com" Subject: Re: [PATCH] cpufreq: Add scaling frequency range support Date: Wed, 29 Jul 2015 02:18:28 +0200 Message-ID: <15808229.KgKF05ecju@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.1.0-rc5+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <55B70ACD.9010402@intel.com> References: <55B6F7C3.8040405@intel.com> <20150728042945.GE1229@linux> <55B70ACD.9010402@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1983 Lines: 45 On Tuesday, July 28, 2015 12:53:33 PM Pan Xinhui wrote: > hi, Viresh > thanks for your reply :) > On 2015年07月28日 12:29, Viresh Kumar wrote: > > On 28-07-15, 11:32, Pan Xinhui wrote: > >> From: Pan Xinhui > >> > >> Userspace at most time do cpufreq tests very much inconveniently. > >> Currently they have to echo min and max cpu freq separately like below: > >> echo 480000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq > >> echo 2240000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq > >> > >> Add scaling_freq_range cpufreq attr to support userspace's demand. > >> Therefore it's easier for testers to write readable scripts like below: > >> echo 480000-2240000 > > >> /sys/devices/system/cpu/cpu0/cpufreq/scaling_freq_range > > > > I don't think this brings any good change, we already have support for > > that with min/max freqs and I don't see how scripts can be less > > readable with that. > > > yes, min/max are supported, however it is inconvenient. sometime it's very easy to cause obscure bugs. > For example, some one might write a script like below. > echo 480000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq > echo 960000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq > .....//other works > echo 1120000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq > echo 2240000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq > ...//other works > > But it did not work when we echo 112000 to min-freq, as the current max freq is smaller than it. > It's hard to figure it out in a big script... we have many such scripts. Fix them, then, pretty please. And adding this attribute is not going to magically fix them, is it? Thanks, Rafael -- 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/