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Subject[PATCH] cpufreq: ondemand: Don't synchronize sample rate unless mulitple cpus present
Date
From: Jocelyn Falempe <jocelyn.falempe@motorola.com>

For UP systems this is not required, and results in a more consistent
sample interval.

Signed-off-by: Jocelyn Falempe <jocelyn.falempe@motorola.com>
Signed-off-by: Mike Chan <mike@android.com>
---
drivers/cpufreq/cpufreq_ondemand.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 4b34ade..d139558 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -576,7 +576,9 @@ static void do_dbs_timer(struct work_struct *work)
/* We want all CPUs to do sampling nearly on same jiffy */
int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);

- delay -= jiffies % delay;
+ if (num_online_cpus() > 1)
+ delay -= jiffies % delay;
+
mutex_lock(&dbs_info->timer_mutex);

/* Common NORMAL_SAMPLE setup */
@@ -601,7 +603,9 @@ static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
{
/* We want all CPUs to do sampling nearly on same jiffy */
int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
- delay -= jiffies % delay;
+
+ if (num_online_cpus() > 1)
+ delay -= jiffies % delay;

dbs_info->sample_type = DBS_NORMAL_SAMPLE;
INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
--
1.6.6


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