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Date: Tue, 29 Apr 2014 23:28:33 +0300 From: Stratos Karafotis <stratosk@...aphore.gr> To: "Rafael J. Wysocki" <rjw@...ysocki.net>, Viresh Kumar <viresh.kumar@...aro.org> CC: "cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>, "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org> Subject: [PATCH] cpufreq: Break out early when frequency equals target_freq 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 <stratosk@...aphore.gr> --- 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; -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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