From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754417AbaEHPqO (ORCPT ); Thu, 8 May 2014 11:46:14 -0400 Received: from sema.semaphore.gr ([78.46.194.137]:55904 "EHLO sema.semaphore.gr" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753994AbaEHPqN (ORCPT ); Thu, 8 May 2014 11:46:13 -0400 Message-ID: <536BA6C1.5000200@semaphore.gr> Date: Thu, 08 May 2014 18:46:09 +0300 From: Stratos Karafotis User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: "Rafael J. Wysocki" , Viresh Kumar CC: "cpufreq@vger.kernel.org" , "linux-pm@vger.kernel.org" , LKML Subject: Re: [PATCH] cpufreq: Break out early when frequency equals target_freq References: <53600B71.2050904@semaphore.gr> In-Reply-To: <53600B71.2050904@semaphore.gr> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/04/2014 11:28 μμ, Stratos Karafotis wrote: > Many drivers keep frequencies in frequency table in ascending > or descending order. When governor tries to change to policy->min > or policy->max respectively then the cpufreq_frequency_table_target > could return on first iteration. This will save some iteration cycles. > > So, break out early when a frequency in cpufreq_frequency_table > equals to target one. > > Testing this during kernel compilation using ondemand governor > with a frequency table in ascending order, the > cpufreq_frequency_table_target returned early on the first > iteration at about 30% of times called. > > Signed-off-by: Stratos Karafotis > --- > drivers/cpufreq/freq_table.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c > index 8e518c6..1632981 100644 > --- a/drivers/cpufreq/freq_table.c > +++ b/drivers/cpufreq/freq_table.c > @@ -137,9 +137,13 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy, > i = pos - table; > if ((freq < policy->min) || (freq > policy->max)) > continue; > + if (freq == target_freq) { > + optimal.driver_data = i; > + break; > + } > switch (relation) { > case CPUFREQ_RELATION_H: > - if (freq <= target_freq) { > + if (freq < target_freq) { > if (freq >= optimal.frequency) { > optimal.frequency = freq; > optimal.driver_data = i; > @@ -152,7 +156,7 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy, > } > break; > case CPUFREQ_RELATION_L: > - if (freq >= target_freq) { > + if (freq > target_freq) { > if (freq <= optimal.frequency) { > optimal.frequency = freq; > optimal.driver_data = i; > Gentle reminder. Thanks, Stratos