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SubjectRe: [PATCH V2] cpufreq: stats: Use local_clock() instead of jiffies
On Tue, Nov 17, 2020 at 12:32 PM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> 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;
> --

Applied as 5.11 material, thanks!

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