[PATCH] cpufreq: stats: Use lock by stat to replace global spin lock

[Kyle Lin]

Stats is updated by each policy, using the lock by stat can
reduce the contention.

Signed-off-by: Kyle Lin <linkyle0...@gmail.com>
---
 drivers/cpufreq/cpufreq_stats.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index e2db5581489a..17beb1bc7e16 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -14,7 +14,6 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 
-static DEFINE_SPINLOCK(cpufreq_stats_lock);
 
 struct cpufreq_stats {
        unsigned int total_trans;
@@ -23,6 +22,7 @@ struct cpufreq_stats {
        unsigned int state_num;
        unsigned int last_index;
        u64 *time_in_state;
+       spinlock_t lock;        /*spinlock for stats update*/
        unsigned int *freq_table;
        unsigned int *trans_table;
 };
@@ -39,12 +39,12 @@ static void cpufreq_stats_clear_table(struct cpufreq_stats 
*stats)
 {
        unsigned int count = stats->max_state;
 
-       spin_lock(&cpufreq_stats_lock);
+       spin_lock(&stats->lock);
        memset(stats->time_in_state, 0, count * sizeof(u64));
        memset(stats->trans_table, 0, count * count * sizeof(int));
        stats->last_time = get_jiffies_64();
        stats->total_trans = 0;
-       spin_unlock(&cpufreq_stats_lock);
+       spin_unlock(&stats->lock);
 }
 
 static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
@@ -62,9 +62,9 @@ static ssize_t show_time_in_state(struct cpufreq_policy 
*policy, char *buf)
        if (policy->fast_switch_enabled)
                return 0;
 
-       spin_lock(&cpufreq_stats_lock);
+       spin_lock(&stats->lock);
        cpufreq_stats_update(stats);
-       spin_unlock(&cpufreq_stats_lock);
+       spin_unlock(&stats->lock);
 
        for (i = 0; i < stats->state_num; i++) {
                len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
@@ -211,6 +211,7 @@ void cpufreq_stats_create_table(struct cpufreq_policy 
*policy)
        stats->state_num = i;
        stats->last_time = get_jiffies_64();
        stats->last_index = freq_table_get_index(stats, policy->cur);
+       spin_lock_init(&stats->lock);
 
        policy->stats = stats;
        ret = sysfs_create_group(&policy->kobj, &stats_attr_group);
@@ -242,11 +243,11 @@ void cpufreq_stats_record_transition(struct 
cpufreq_policy *policy,
        if (old_index == -1 || new_index == -1 || old_index == new_index)
                return;
 
-       spin_lock(&cpufreq_stats_lock);
+       spin_lock(&stats->lock);
        cpufreq_stats_update(stats);
 
        stats->last_index = new_index;
        stats->trans_table[old_index * stats->max_state + new_index]++;
        stats->total_trans++;
-       spin_unlock(&cpufreq_stats_lock);
+       spin_unlock(&stats->lock);
 }
-- 
2.21.0.392.gf8f6787159e-goog