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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>
This commit is contained in:
Stratos Karafotis 2014-05-14 21:05:52 +03:00 committed by Rafael J. Wysocki
parent e7b453d3dd
commit 1e4988563d
1 changed files with 6 additions and 2 deletions
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8
drivers/cpufreq/freq_table.c
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@ -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;