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Subject[PATCH] cpufreq: ondemand: Replace down_differential tuner with adj_up_threshold
In order to avoid the calculation of up_threshold - down_differential
every time that the frequency must be decreased, we replace the
down_differential tuner with the adj_up_threshold which keeps the
difference across multiple checks.

Update the adj_up_threshold only when the up_theshold is also updated.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
---
drivers/cpufreq/cpufreq_governor.h | 2 +-
drivers/cpufreq/cpufreq_ondemand.c | 16 ++++++++++------
2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index f661654..4250944 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -108,7 +108,7 @@ struct od_dbs_tuners {
unsigned int sampling_rate;
unsigned int sampling_down_factor;
unsigned int up_threshold;
- unsigned int down_differential;
+ unsigned int adj_up_threshold;
unsigned int powersave_bias;
unsigned int io_is_busy;
};
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 7731f7c..2cc76ad 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -47,7 +47,8 @@ static struct cpufreq_governor cpufreq_gov_ondemand;
static struct od_dbs_tuners od_tuners = {
.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
- .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
+ .adj_up_threshold = DEF_FREQUENCY_UP_THRESHOLD -
+ DEF_FREQUENCY_DOWN_DIFFERENTIAL,
.ignore_nice = 0,
.powersave_bias = 0,
};
@@ -192,11 +193,9 @@ static void od_check_cpu(int cpu, unsigned int load_freq)
* support the current CPU usage without triggering the up policy. To be
* safe, we focus 10 points under the threshold.
*/
- if (load_freq < (od_tuners.up_threshold - od_tuners.down_differential) *
- policy->cur) {
+ if (load_freq < od_tuners.adj_up_threshold * policy->cur) {
unsigned int freq_next;
- freq_next = load_freq / (od_tuners.up_threshold -
- od_tuners.down_differential);
+ freq_next = load_freq / od_tuners.adj_up_threshold;

/* No longer fully busy, reset rate_mult */
dbs_info->rate_mult = 1;
@@ -351,6 +350,10 @@ static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
input < MIN_FREQUENCY_UP_THRESHOLD) {
return -EINVAL;
}
+ /* Calculate the new adj_up_threshold */
+ od_tuners.adj_up_threshold += input;
+ od_tuners.adj_up_threshold -= od_tuners.up_threshold;
+
od_tuners.up_threshold = input;
return count;
}
@@ -507,7 +510,8 @@ static int __init cpufreq_gov_dbs_init(void)
if (idle_time != -1ULL) {
/* Idle micro accounting is supported. Use finer thresholds */
od_tuners.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
- od_tuners.down_differential = MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
+ od_tuners.adj_up_threshold = MICRO_FREQUENCY_UP_THRESHOLD -
+ MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
/*
* In nohz/micro accounting case we set the minimum frequency
* not depending on HZ, but fixed (very low). The deferred
--
1.8.1


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