cpufreq interactive governor: Update target frequency calculation

Updated target frequency calculation algorithm to take into account
current rate CPU is running at:

- When CPU is running below go_maxspeed_load threshold, adjust the
target frequency based on current rate to reach tunable sustainable
load (instead of applying cpu load to max possible cpu rate).

Tuned by setting new node ("0" falls back to using max_rate):
/sys/devices/system/cpu/cpufreq/interactive/sustain_load

- When CPU is running at/above go_maxspeed_load threshold, ramp the
target frequency starting from current exponentially with tunable base
(instead of immediate jump to maximum cpu rate).

Tuned by setting new node ("0" falls back to jump to max_rate):
/sys/devices/system/cpu/cpufreq/interactive/boost_factor

Defaults for the new tunning parameters are set to "0" - so no changes
in governor default behavior.

Change-Id: I0137c2fbc9c2cc1ae85869593319324d31974e1a
Reviewed-on: http://git-master/r/38817
Reviewed-by: Karan Jhavar <kjhavar@nvidia.com>
Tested-by: Karan Jhavar <kjhavar@nvidia.com>
Reviewed-by: Narendra Damahe <ndamahe@nvidia.com>
Reviewed-by: Chih-Lung Huang <lhuang@nvidia.com>
Reviewed-by: Jeremy Wyman <jwyman@nvidia.com>

1 files changed, 76 insertions, 10 deletions

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index 81783286cad2..8ba956a43910 100644
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -61,6 +61,15 @@ static spinlock_t down_cpumask_lock;
 #define DEFAULT_GO_MAXSPEED_LOAD 85
 static unsigned long go_maxspeed_load;
 
+/* Base of exponential raise to max speed; if 0 - jump to maximum */
+static unsigned long boost_factor;
+
+/*
+ * Targeted sustainable load relatively to current frequency.
+ * If 0, target is set realtively to the max speed
+ */
+static unsigned long sustain_load;
+
 /*
  * The minimum amount of time to spend at a frequency before we can ramp down.
  */
@@ -167,6 +176,36 @@ struct cpufreq_governor cpufreq_gov_interactive = {
 	.owner = THIS_MODULE,
 };
 
+static unsigned int cpufreq_interactive_get_target(
+	int cpu_load, int load_since_change, struct cpufreq_policy *policy)
+{
+	unsigned int target_freq;
+
+	/*
+	 * Choose greater of short-term load (since last idle timer
+	 * started or timer function re-armed itself) or long-term load
+	 * (since last frequency change).
+	 */
+	if (load_since_change > cpu_load)
+		cpu_load = load_since_change;
+
+	if (cpu_load >= go_maxspeed_load) {
+		if (!boost_factor)
+			return policy->max;
+
+		target_freq = policy->cur * boost_factor;
+	}
+	else {
+		if (!sustain_load)
+			return policy->max * cpu_load / 100;
+
+		target_freq = policy->cur * cpu_load / sustain_load;
+	}
+
+	target_freq = min(target_freq, policy->max);
+	return target_freq;
+}
+
 static void cpufreq_interactive_timer(unsigned long data)
 {
 	unsigned int delta_idle;
@@ -243,17 +282,12 @@ static void cpufreq_interactive_timer(unsigned long data)
 			100 * (delta_time - delta_idle) / delta_time;
 
 	/*
-	 * Choose greater of short-term load (since last idle timer
-	 * started or timer function re-armed itself) or long-term load
-	 * (since last frequency change).
+	 * Combine short-term load (since last idle timer started or timer
+	 * function re-armed itself) and long-term load (since last frequency
+	 * change) to determine new target frequency
 	 */
-	if (load_since_change > cpu_load)
-		cpu_load = load_since_change;
-
-	if (cpu_load >= go_maxspeed_load)
-		new_freq = pcpu->policy->max;
-	else
-		new_freq = pcpu->policy->max * cpu_load / 100;
+	new_freq = cpufreq_interactive_get_target(cpu_load, load_since_change,
+						  pcpu->policy);
 
 	if (cpufreq_frequency_table_target(pcpu->policy, pcpu->freq_table,
 					   new_freq, CPUFREQ_RELATION_H,
@@ -542,6 +576,36 @@ static ssize_t store_go_maxspeed_load(struct kobject *kobj,
 static struct global_attr go_maxspeed_load_attr = __ATTR(go_maxspeed_load, 0644,
 		show_go_maxspeed_load, store_go_maxspeed_load);
 
+static ssize_t show_boost_factor(struct kobject *kobj,
+				     struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", boost_factor);
+}
+
+static ssize_t store_boost_factor(struct kobject *kobj,
+			struct attribute *attr, const char *buf, size_t count)
+{
+	return strict_strtoul(buf, 0, &boost_factor);
+}
+
+static struct global_attr boost_factor_attr = __ATTR(boost_factor, 0644,
+		show_boost_factor, store_boost_factor);
+
+static ssize_t show_sustain_load(struct kobject *kobj,
+				     struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", sustain_load);
+}
+
+static ssize_t store_sustain_load(struct kobject *kobj,
+			struct attribute *attr, const char *buf, size_t count)
+{
+	return strict_strtoul(buf, 0, &sustain_load);
+}
+
+static struct global_attr sustain_load_attr = __ATTR(sustain_load, 0644,
+		show_sustain_load, store_sustain_load);
+
 static ssize_t show_min_sample_time(struct kobject *kobj,
 				struct attribute *attr, char *buf)
 {
@@ -559,6 +623,8 @@ static struct global_attr min_sample_time_attr = __ATTR(min_sample_time, 0644,
 
 static struct attribute *interactive_attributes[] = {
 	&go_maxspeed_load_attr.attr,
+	&boost_factor_attr.attr,
+	&sustain_load_attr.attr,
 	&min_sample_time_attr.attr,
 	NULL,
 };