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Subject[PATCH V2] cpufreq: stats: Use local_clock() instead of jiffies
Date
local_clock() has better precision and accuracy as compared to jiffies,
lets use it for time management in cpufreq stats.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
V2:
- Doesn't change the units to msec and use local_clock() instead of
ktime.

drivers/cpufreq/cpufreq_stats.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index 6cd5c8ab5d49..da717f7cd9a9 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -9,9 +9,9 @@
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/module.h>
+#include <linux/sched/clock.h>
#include <linux/slab.h>

-
struct cpufreq_stats {
unsigned int total_trans;
unsigned long long last_time;
@@ -30,7 +30,7 @@ struct cpufreq_stats {
static void cpufreq_stats_update(struct cpufreq_stats *stats,
unsigned long long time)
{
- unsigned long long cur_time = get_jiffies_64();
+ unsigned long long cur_time = local_clock();

stats->time_in_state[stats->last_index] += cur_time - time;
stats->last_time = cur_time;
@@ -42,7 +42,7 @@ static void cpufreq_stats_reset_table(struct cpufreq_stats *stats)

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->last_time = local_clock();
stats->total_trans = 0;

/* Adjust for the time elapsed since reset was requested */
@@ -82,18 +82,18 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
* before the reset_pending read above.
*/
smp_rmb();
- time = get_jiffies_64() - READ_ONCE(stats->reset_time);
+ time = local_clock() - READ_ONCE(stats->reset_time);
} else {
time = 0;
}
} else {
time = stats->time_in_state[i];
if (i == stats->last_index)
- time += get_jiffies_64() - stats->last_time;
+ time += local_clock() - stats->last_time;
}

len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
- jiffies_64_to_clock_t(time));
+ nsec_to_clock_t(time));
}
return len;
}
@@ -109,7 +109,7 @@ static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,
* Defer resetting of stats to cpufreq_stats_record_transition() to
* avoid races.
*/
- WRITE_ONCE(stats->reset_time, get_jiffies_64());
+ WRITE_ONCE(stats->reset_time, local_clock());
/*
* The memory barrier below is to prevent the readers of reset_time from
* seeing a stale or partially updated value.
@@ -249,7 +249,7 @@ void cpufreq_stats_create_table(struct cpufreq_policy *policy)
stats->freq_table[i++] = pos->frequency;

stats->state_num = i;
- stats->last_time = get_jiffies_64();
+ stats->last_time = local_clock();
stats->last_index = freq_table_get_index(stats, policy->cur);

policy->stats = stats;
--
2.25.0.rc1.19.g042ed3e048af
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