cpufreq: interactive: add sysfs control for timer rate

Add a new sysfs control that tunes the rate of the timer used to
increase cpu frequency

Change-Id: I1aa13ae54bb43aff5b3688984d2955f56aae1658
Signed-off-by: Allen Martin <amartin@nvidia.com>

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index fe20e31..6a98631 100644 (file)
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -66,6 +66,12 @@ static unsigned long go_maxspeed_load;
 #define DEFAULT_MIN_SAMPLE_TIME 80000;
 static unsigned long min_sample_time;
 
+/*
+ * The sample rate of the timer used to increase frequency
+ */
+#define DEFAULT_TIMER_RATE 30000;
+static unsigned long timer_rate;
+
 static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
                unsigned int event);
 
@@ -219,7 +225,7 @@ rearm:
 
                pcpu->time_in_idle = get_cpu_idle_time_us(
                        data, &pcpu->idle_exit_time);
-               mod_timer(&pcpu->cpu_timer, jiffies + 2);
+               mod_timer(&pcpu->cpu_timer, jiffies + usecs_to_jiffies(timer_rate));
        }
 
 exit:
@@ -254,7 +260,7 @@ static void cpufreq_interactive_idle_start(void)
                        pcpu->time_in_idle = get_cpu_idle_time_us(
                                smp_processor_id(), &pcpu->idle_exit_time);
                        pcpu->timer_idlecancel = 0;
-                       mod_timer(&pcpu->cpu_timer, jiffies + 2);
+                       mod_timer(&pcpu->cpu_timer, jiffies + usecs_to_jiffies(timer_rate));
                }
 #endif
        } else {
@@ -304,7 +310,7 @@ static void cpufreq_interactive_idle_end(void)
                        get_cpu_idle_time_us(smp_processor_id(),
                                             &pcpu->idle_exit_time);
                pcpu->timer_idlecancel = 0;
-               mod_timer(&pcpu->cpu_timer, jiffies + 2);
+               mod_timer(&pcpu->cpu_timer, jiffies + usecs_to_jiffies(timer_rate));
        }
 
 }
@@ -429,9 +435,32 @@ static ssize_t store_min_sample_time(struct kobject *kobj,
 static struct global_attr min_sample_time_attr = __ATTR(min_sample_time, 0644,
                show_min_sample_time, store_min_sample_time);
 
+static ssize_t show_timer_rate(struct kobject *kobj,
+                       struct attribute *attr, char *buf)
+{
+       return sprintf(buf, "%lu\n", timer_rate);
+}
+
+static ssize_t store_timer_rate(struct kobject *kobj,
+                       struct attribute *attr, const char *buf, size_t count)
+{
+       int ret;
+       unsigned long val;
+
+       ret = strict_strtoul(buf, 0, &val);
+       if (ret < 0)
+               return ret;
+       timer_rate = val;
+       return count;
+}
+
+static struct global_attr timer_rate_attr = __ATTR(timer_rate, 0644,
+               show_timer_rate, store_timer_rate);
+
 static struct attribute *interactive_attributes[] = {
        &go_maxspeed_load_attr.attr,
        &min_sample_time_attr.attr,
+       &timer_rate_attr.attr,
        NULL,
 };
 
@@ -547,6 +576,7 @@ static int __init cpufreq_interactive_init(void)
 
        go_maxspeed_load = DEFAULT_GO_MAXSPEED_LOAD;
        min_sample_time = DEFAULT_MIN_SAMPLE_TIME;
+       timer_rate = DEFAULT_TIMER_RATE;
 
        /* Initalize per-cpu timers */
        for_each_possible_cpu(i) {