[PATCH] cpufreq-stats: fix time_in_state statistics

[PATCH] cpufreq-stats: fix time_in_state statistics

[Andreas Schwab]

The time_in_state numbers are in units of jiffies, not cputime.

Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
---
 drivers/cpufreq/cpufreq_stats.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
index d37568c..10e6138 100644
--- a/drivers/cpufreq/cpufreq_stats.c
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -81,7 +81,7 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
 	for (i = 0; i < stat->state_num; i++) {
 		len += sprintf(buf + len, "%u %llu\n", stat->freq_table[i],
 			(unsigned long long)
-			cputime64_to_clock_t(stat->time_in_state[i]));
+			jiffies_64_to_clock_t(stat->time_in_state[i]));
 	}
 	return len;
 }
-- 
1.8.3.4

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Re: [PATCH] cpufreq-stats: fix time_in_state statistics

[Viresh Kumar]

Please see MAINTAINERS file to get list of people/lists you need
to send your patch to.

On Sat, Aug 3, 2013 at 12:01 AM, Andreas Schwab <schwab@linux-m68k.org> wrote:
> The time_in_state numbers are in units of jiffies, not cputime.
>
> Signed-off-by: Andreas Schwab <schwab@linux-m68k.org>
> ---
>  drivers/cpufreq/cpufreq_stats.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
> index d37568c..10e6138 100644
> --- a/drivers/cpufreq/cpufreq_stats.c
> +++ b/drivers/cpufreq/cpufreq_stats.c
> @@ -81,7 +81,7 @@ static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
>         for (i = 0; i < stat->state_num; i++) {
>                 len += sprintf(buf + len, "%u %llu\n", stat->freq_table[i],
>                         (unsigned long long)
> -                       cputime64_to_clock_t(stat->time_in_state[i]));
> +                       jiffies_64_to_clock_t(stat->time_in_state[i]));

I tried to go to the history a bit but really couldn't make out what was
the real intention initially:

Following patches did this change:

-               stat->time_in_state[stat->last_index] +=
-                       delta_time(stat->last_time, jiffies);
-       stat->last_time = jiffies;
+               stat->time_in_state[stat->last_index] =
+                       cputime64_add(stat->time_in_state[stat->last_index],
+                                     cputime_sub(cur_time, stat->last_time));

commit 58f1df25403988b73d7129fcd2c4d4c24017f1af
Author: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Date:   Wed May 25 14:46:50 2005 -0700

    [PATCH] cpufreq-stats driver updates


And it was then simplified by:

commit 648616343cdbe904c585a6c12e323d3b3c72e46f
Author: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date:   Thu Dec 15 14:56:09 2011 +0100

    [S390] cputime: add sparse checking and cleanup

-               stat->time_in_state[stat->last_index] =
-                       cputime64_add(stat->time_in_state[stat->last_index],
-                                     cputime_sub(cur_time, stat->last_time));
+               stat->time_in_state[stat->last_index] +=
+                       cur_time - stat->last_time;


And obviously cur_time is in jiffies... I am okay with your patch
if Rafael doesn't see any issues with it...

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>