From: Stratos Karafotis <stratosk@semaphore.gr>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Viresh Kumar <viresh.kumar@linaro.org>
Cc: "cpufreq@vger.kernel.org" <cpufreq@vger.kernel.org>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH] cpufreq: Break out early when frequency equals target_freq
Date: Tue, 29 Apr 2014 23:28:33 +0300 [thread overview]
Message-ID: <53600B71.2050904@semaphore.gr> (raw)
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;
--
1.9.0
next reply other threads:[~2014-04-29 20:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-29 20:28 Stratos Karafotis [this message]
2014-05-08 15:46 ` [PATCH] cpufreq: Break out early when frequency equals target_freq Stratos Karafotis
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