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Date: Wed, 20 Feb 2013 22:50:29 +0200
From: Stratos Karafotis <stratosk@...aphore.gr>
To: "Rafael J. Wysocki" <rjw@...k.pl>
CC: cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH linux-next] cpufreq: ondemand: Calculate gradient of CPU load
to early increase frequency
Instead of checking only the absolute value of CPU load_freq to increase
frequency, we detect forthcoming CPU load rise and increase frequency
earlier.
Every sampling rate, we calculate the gradient of load_freq.
If it is too steep we assume that the load most probably will
go over up_threshold in next iteration(s). We reduce up_threshold
by early_differential to achieve frequency increase in the current
iteration.
A new tuner early_demand is introduced to enable this functionality
(disabled by default). Also we use new tuners to control early demand:
- early_differential: controls the final up_threshold
- grad_up_threshold: over this gradient of load we will decrease
up_threshold by early_differential.
Signed-off-by: Stratos Karafotis <stratosk@...aphore.gr>
---
drivers/cpufreq/cpufreq_governor.c | 1 +
drivers/cpufreq/cpufreq_governor.h | 4 ++++
drivers/cpufreq/cpufreq_ondemand.c | 41 +++++++++++++++++++++++++++++++++++++-
3 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 5a76086..348cb80 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -276,6 +276,7 @@ int cpufreq_governor_dbs(struct dbs_data *dbs_data,
} else {
od_dbs_info->rate_mult = 1;
od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
+ od_dbs_info->prev_load_freq = 0;
od_ops->powersave_bias_init_cpu(cpu);
if (!policy->governor->initialized)
diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index d2ac911..d1425a7 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -94,6 +94,7 @@ struct od_cpu_dbs_info_s {
unsigned int freq_hi_jiffies;
unsigned int rate_mult;
unsigned int sample_type:1;
+ unsigned int prev_load_freq;
};
struct cs_cpu_dbs_info_s {
@@ -112,6 +113,9 @@ struct od_dbs_tuners {
unsigned int adj_up_threshold;
unsigned int powersave_bias;
unsigned int io_is_busy;
+ unsigned int early_differential;
+ unsigned int grad_up_threshold;
+ unsigned int early_demand;
};
struct cs_dbs_tuners {
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index f3eb26c..458806f 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -30,6 +30,8 @@
#define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
#define DEF_FREQUENCY_UP_THRESHOLD (80)
#define DEF_SAMPLING_DOWN_FACTOR (1)
+#define DEF_GRAD_UP_THESHOLD (50)
+#define DEF_EARLY_DIFFERENTIAL (45)
#define MAX_SAMPLING_DOWN_FACTOR (100000)
#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
#define MICRO_FREQUENCY_UP_THRESHOLD (95)
@@ -49,8 +51,11 @@ static struct od_dbs_tuners od_tuners = {
.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
.adj_up_threshold = DEF_FREQUENCY_UP_THRESHOLD -
DEF_FREQUENCY_DOWN_DIFFERENTIAL,
+ .early_differential = DEF_EARLY_DIFFERENTIAL,
+ .grad_up_threshold = DEF_GRAD_UP_THESHOLD,
.ignore_nice = 0,
.powersave_bias = 0,
+ .early_demand = 0,
};
static void ondemand_powersave_bias_init_cpu(int cpu)
@@ -170,11 +175,29 @@ static void od_check_cpu(int cpu, unsigned int load_freq)
{
struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
+ unsigned int up_threshold = od_tuners.up_threshold;
+ unsigned int grad;
dbs_info->freq_lo = 0;
+ /*
+ * Calculate the gradient of load_freq. If it is too steep we assume
+ * that the load will go over up_threshold in next iteration(s). We
+ * reduce up_threshold by early_differential to achieve frequency
+ * increase earlier
+ */
+ if (od_tuners.early_demand) {
+ if (load_freq > dbs_info->prev_load_freq) {
+ grad = load_freq - dbs_info->prev_load_freq;
+
+ if (grad > od_tuners.grad_up_threshold * policy->cur)
+ up_threshold -= od_tuners.early_differential;
+ }
+ dbs_info->prev_load_freq = load_freq;
+ }
+
/* Check for frequency increase */
- if (load_freq > od_tuners.up_threshold * policy->cur) {
+ if (load_freq > up_threshold * policy->cur) {
/* If switching to max speed, apply sampling_down_factor */
if (policy->cur < policy->max)
dbs_info->rate_mult =
@@ -438,12 +461,26 @@ static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
return count;
}
+static ssize_t store_early_demand(struct kobject *a, struct attribute *b,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+
+ ret = sscanf(buf, "%u", &input);
+ if (ret != 1)
+ return -EINVAL;
+ od_tuners.early_demand = !!input;
+ return count;
+}
+
show_one(od, sampling_rate, sampling_rate);
show_one(od, io_is_busy, io_is_busy);
show_one(od, up_threshold, up_threshold);
show_one(od, sampling_down_factor, sampling_down_factor);
show_one(od, ignore_nice_load, ignore_nice);
show_one(od, powersave_bias, powersave_bias);
+show_one(od, early_demand, early_demand);
define_one_global_rw(sampling_rate);
define_one_global_rw(io_is_busy);
@@ -452,6 +489,7 @@ define_one_global_rw(sampling_down_factor);
define_one_global_rw(ignore_nice_load);
define_one_global_rw(powersave_bias);
define_one_global_ro(sampling_rate_min);
+define_one_global_rw(early_demand);
static struct attribute *dbs_attributes[] = {
&sampling_rate_min.attr,
@@ -461,6 +499,7 @@ static struct attribute *dbs_attributes[] = {
&ignore_nice_load.attr,
&powersave_bias.attr,
&io_is_busy.attr,
+ &early_demand.attr,
NULL
};
--
1.8.1.2
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