cpufreq: interactive: restructure CPUFREQ_GOV_LIMITS

The cpufreq_interactive_timer gets cancelled and rescheduled
whenever the cpufreq_policy is changed. When the cpufreq policy is
changed at a rate faster than the sampling_rate of the interactive
governor, then the governor misses to change the target frequency
for long duration. The patch removes the need of cancelling the
timers when policy->min is changed.

Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
Change-Id: Ibd98d151e1c73b8bd969484583ff98ee9f1135ef

diff --git a/drivers/cpufreq/cpufreq_interactive.c b/drivers/cpufreq/cpufreq_interactive.c
index 786fd012e8b222dec030223643f3ae52b4993aeb..0e3e45e9e084b2b8695aaa7c0055b587af848e93 100644 (file)
--- a/drivers/cpufreq/cpufreq_interactive.c
+++ b/drivers/cpufreq/cpufreq_interactive.c
@@ -44,8 +44,10 @@ struct cpufreq_interactive_cpuinfo {
        u64 cputime_speedadj_timestamp;
        struct cpufreq_policy *policy;
        struct cpufreq_frequency_table *freq_table;
+       spinlock_t target_freq_lock; /*protects target freq */
        unsigned int target_freq;
        unsigned int floor_freq;
+       unsigned int max_freq;
        u64 floor_validate_time;
        u64 hispeed_validate_time;
        struct rw_semaphore enable_sem;
@@ -358,6 +360,7 @@ static void cpufreq_interactive_timer(unsigned long data)
        if (WARN_ON_ONCE(!delta_time))
                goto rearm;
 
+       spin_lock_irqsave(&pcpu->target_freq_lock, flags);
        do_div(cputime_speedadj, delta_time);
        loadadjfreq = (unsigned int)cputime_speedadj * 100;
        cpu_load = loadadjfreq / pcpu->target_freq;
@@ -383,6 +386,7 @@ static void cpufreq_interactive_timer(unsigned long data)
                trace_cpufreq_interactive_notyet(
                        data, cpu_load, pcpu->target_freq,
                        pcpu->policy->cur, new_freq);
+               spin_unlock_irqrestore(&pcpu->target_freq_lock, flags);
                goto rearm;
        }
 
@@ -390,8 +394,10 @@ static void cpufreq_interactive_timer(unsigned long data)
 
        if (cpufreq_frequency_table_target(pcpu->policy, pcpu->freq_table,
                                           new_freq, CPUFREQ_RELATION_L,
-                                          &index))
+                                          &index)) {
+               spin_unlock_irqrestore(&pcpu->target_freq_lock, flags);
                goto rearm;
+       }
 
        new_freq = pcpu->freq_table[index].frequency;
 
@@ -405,6 +411,7 @@ static void cpufreq_interactive_timer(unsigned long data)
                        trace_cpufreq_interactive_notyet(
                                data, cpu_load, pcpu->target_freq,
                                pcpu->policy->cur, new_freq);
+                       spin_unlock_irqrestore(&pcpu->target_freq_lock, flags);
                        goto rearm;
                }
        }
@@ -426,6 +433,7 @@ static void cpufreq_interactive_timer(unsigned long data)
                trace_cpufreq_interactive_already(
                        data, cpu_load, pcpu->target_freq,
                        pcpu->policy->cur, new_freq);
+               spin_unlock_irqrestore(&pcpu->target_freq_lock, flags);
                goto rearm_if_notmax;
        }
 
@@ -433,6 +441,7 @@ static void cpufreq_interactive_timer(unsigned long data)
                                         pcpu->policy->cur, new_freq);
 
        pcpu->target_freq = new_freq;
+       spin_unlock_irqrestore(&pcpu->target_freq_lock, flags);
        spin_lock_irqsave(&speedchange_cpumask_lock, flags);
        cpumask_set_cpu(data, &speedchange_cpumask);
        spin_unlock_irqrestore(&speedchange_cpumask_lock, flags);
@@ -576,16 +585,17 @@ static void cpufreq_interactive_boost(void)
 {
        int i;
        int anyboost = 0;
-       unsigned long flags;
+       unsigned long flags[2];
        struct cpufreq_interactive_cpuinfo *pcpu;
        struct cpufreq_interactive_tunables *tunables;
 
-       spin_lock_irqsave(&speedchange_cpumask_lock, flags);
+       spin_lock_irqsave(&speedchange_cpumask_lock, flags[0]);
 
        for_each_online_cpu(i) {
                pcpu = &per_cpu(cpuinfo, i);
                tunables = pcpu->policy->governor_data;
 
+               spin_lock_irqsave(&pcpu->target_freq_lock, flags[1]);
                if (pcpu->target_freq < tunables->hispeed_freq) {
                        pcpu->target_freq = tunables->hispeed_freq;
                        cpumask_set_cpu(i, &speedchange_cpumask);
@@ -601,9 +611,10 @@ static void cpufreq_interactive_boost(void)
 
                pcpu->floor_freq = tunables->hispeed_freq;
                pcpu->floor_validate_time = ktime_to_us(ktime_get());
+               spin_unlock_irqrestore(&pcpu->target_freq_lock, flags[1]);
        }
 
-       spin_unlock_irqrestore(&speedchange_cpumask_lock, flags);
+       spin_unlock_irqrestore(&speedchange_cpumask_lock, flags[0]);
 
        if (anyboost)
                wake_up_process(speedchange_task);
@@ -1114,6 +1125,7 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
        struct cpufreq_interactive_cpuinfo *pcpu;
        struct cpufreq_frequency_table *freq_table;
        struct cpufreq_interactive_tunables *tunables;
+       unsigned long flags;
 
        if (have_governor_per_policy())
                tunables = policy->governor_data;
@@ -1215,6 +1227,7 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
                                ktime_to_us(ktime_get());
                        pcpu->hispeed_validate_time =
                                pcpu->floor_validate_time;
+                       pcpu->max_freq = policy->max;
                        down_write(&pcpu->enable_sem);
                        del_timer_sync(&pcpu->cpu_timer);
                        del_timer_sync(&pcpu->cpu_slack_timer);
@@ -1250,29 +1263,37 @@ static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
                for_each_cpu(j, policy->cpus) {
                        pcpu = &per_cpu(cpuinfo, j);
 
-                       /* hold write semaphore to avoid race */
-                       down_write(&pcpu->enable_sem);
+                       down_read(&pcpu->enable_sem);
                        if (pcpu->governor_enabled == 0) {
-                               up_write(&pcpu->enable_sem);
+                               up_read(&pcpu->enable_sem);
                                continue;
                        }
 
-                       /* update target_freq firstly */
+                       spin_lock_irqsave(&pcpu->target_freq_lock, flags);
                        if (policy->max < pcpu->target_freq)
                                pcpu->target_freq = policy->max;
                        else if (policy->min > pcpu->target_freq)
                                pcpu->target_freq = policy->min;
 
-                       /* Reschedule timer.
+                       spin_unlock_irqrestore(&pcpu->target_freq_lock, flags);
+                       up_read(&pcpu->enable_sem);
+
+                       /* Reschedule timer only if policy->max is raised.
                         * Delete the timers, else the timer callback may
                         * return without re-arm the timer when failed
                         * acquire the semaphore. This race may cause timer
                         * stopped unexpectedly.
                         */
-                       del_timer_sync(&pcpu->cpu_timer);
-                       del_timer_sync(&pcpu->cpu_slack_timer);
-                       cpufreq_interactive_timer_start(tunables, j);
-                       up_write(&pcpu->enable_sem);
+
+                       if (policy->max > pcpu->max_freq) {
+                               down_write(&pcpu->enable_sem);
+                               del_timer_sync(&pcpu->cpu_timer);
+                               del_timer_sync(&pcpu->cpu_slack_timer);
+                               cpufreq_interactive_timer_start(tunables, j);
+                               up_write(&pcpu->enable_sem);
+                       }
+
+                       pcpu->max_freq = policy->max;
                }
                break;
        }
@@ -1308,6 +1329,7 @@ static int __init cpufreq_interactive_init(void)
                init_timer(&pcpu->cpu_slack_timer);
                pcpu->cpu_slack_timer.function = cpufreq_interactive_nop_timer;
                spin_lock_init(&pcpu->load_lock);
+               spin_lock_init(&pcpu->target_freq_lock);
                init_rwsem(&pcpu->enable_sem);
        }