Commit 1e498856 authored May 14, 2014 by Stratos Karafotis Committed by Rafael J. Wysocki May 20, 2014

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@semaphore.gr>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

parent e7b453d3

drivers/cpufreq/freq_table.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -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;