cpufreq: interactive: don't drop speed if recently at higher load

Apply min_sample_time to the last time the current target speed
was originally requested or re-validated as appropriate for the
current load, not to the time since the current speed was
originally set.  Avoids periodic dips in speed during bursty
loads.

Change-Id: I250bda657985de60373f9897cc41f480664d51a1
Signed-off-by: Todd Poynor <toddpoynor@google.com>

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index 12345c7bec28a3c12267879dfdf6222092ba5af9..59e7779a4a09849406b9be9cfe6c0bd4277497f0 100644 (file)
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -44,8 +44,8 @@ struct cpufreq_interactive_cpuinfo {
        u64 idle_exit_time;
        u64 timer_run_time;
        int idling;
-       u64 freq_change_time;
-       u64 freq_change_time_in_idle;
+       u64 target_set_time;
+       u64 target_set_time_in_idle;
        struct cpufreq_policy *policy;
        struct cpufreq_frequency_table *freq_table;
        unsigned int target_freq;
@@ -148,8 +148,9 @@ static void cpufreq_interactive_timer(unsigned long data)
        else
                cpu_load = 100 * (delta_time - delta_idle) / delta_time;
 
-       delta_idle = (unsigned int)(now_idle - pcpu->freq_change_time_in_idle);
-       delta_time = (unsigned int)(pcpu->timer_run_time - pcpu->freq_change_time);
+       delta_idle = (unsigned int)(now_idle - pcpu->target_set_time_in_idle);
+       delta_time = (unsigned int)(pcpu->timer_run_time -
+                                   pcpu->target_set_time);
 
        if ((delta_time == 0) || (delta_idle > delta_time))
                load_since_change = 0;
@@ -188,19 +189,12 @@ static void cpufreq_interactive_timer(unsigned long data)
 
        new_freq = pcpu->freq_table[index].frequency;
 
-       if (pcpu->target_freq == new_freq)
-       {
-               trace_cpufreq_interactive_already(data, cpu_load,
-                                                 pcpu->target_freq, new_freq);
-               goto rearm_if_notmax;
-       }
-
        /*
         * Do not scale down unless we have been at this frequency for the
         * minimum sample time.
         */
        if (new_freq < pcpu->target_freq) {
-               if (pcpu->timer_run_time - pcpu->freq_change_time
+               if (pcpu->timer_run_time - pcpu->target_set_time
                    < min_sample_time) {
                        trace_cpufreq_interactive_notyet(data, cpu_load,
                                         pcpu->target_freq, new_freq);
@@ -208,6 +202,15 @@ static void cpufreq_interactive_timer(unsigned long data)
                }
        }
 
+       pcpu->target_set_time_in_idle = now_idle;
+       pcpu->target_set_time = pcpu->timer_run_time;
+
+       if (pcpu->target_freq == new_freq) {
+               trace_cpufreq_interactive_already(data, cpu_load,
+                                                 pcpu->target_freq, new_freq);
+               goto rearm_if_notmax;
+       }
+
        trace_cpufreq_interactive_target(data, cpu_load, pcpu->target_freq,
                                         new_freq);
 
@@ -394,10 +397,6 @@ static int cpufreq_interactive_up_task(void *data)
                                                        max_freq,
                                                        CPUFREQ_RELATION_H);
                        mutex_unlock(&set_speed_lock);
-
-                       pcpu->freq_change_time_in_idle =
-                               get_cpu_idle_time_us(cpu,
-                                                    &pcpu->freq_change_time);
                        trace_cpufreq_interactive_up(cpu, pcpu->target_freq,
                                                     pcpu->policy->cur);
                }
@@ -443,9 +442,6 @@ static void cpufreq_interactive_freq_down(struct work_struct *work)
                                                CPUFREQ_RELATION_H);
 
                mutex_unlock(&set_speed_lock);
-               pcpu->freq_change_time_in_idle =
-                       get_cpu_idle_time_us(cpu,
-                                            &pcpu->freq_change_time);
                trace_cpufreq_interactive_down(cpu, pcpu->target_freq,
                                               pcpu->policy->cur);
        }
@@ -575,9 +571,9 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
                        pcpu->policy = policy;
                        pcpu->target_freq = policy->cur;
                        pcpu->freq_table = freq_table;
-                       pcpu->freq_change_time_in_idle =
+                       pcpu->target_set_time_in_idle =
                                get_cpu_idle_time_us(j,
-                                            &pcpu->freq_change_time);
+                                            &pcpu->target_set_time);
                        pcpu->governor_enabled = 1;
                        smp_wmb();
                }