| Message ID | 53600B71.2050904@semaphore.gr (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On 29/04/2014 11:28 ??, 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 <stratosk@semaphore.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; > Gentle reminder. Thanks, Stratos -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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;
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> --- drivers/cpufreq/freq_table.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)