From a857c0b9e24e39fe5be82451b65377795f9538d8 Mon Sep 17 00:00:00 2001 From: Andreas Schwab Date: Sat, 7 Sep 2013 18:35:08 +0200 Subject: [PATCH] cpufreq: Fix wrong time unit conversion The time spent by a CPU under a given frequency is stored in jiffies unit in the cpu var cpufreq_stats_table->time_in_state[i], i being the index of the frequency. This is what is displayed in the following file on the right column: cat /sys/devices/system/cpu/cpuX/cpufreq/stats/time_in_state 2301000 19835820 2300000 3172 [...] Now cpufreq converts this jiffies unit delta to clock_t before returning it to the user as in the above file. And that conversion is achieved using the API cputime64_to_clock_t(). Although it accidentally works on traditional tick based cputime accounting, where cputime_t maps directly to jiffies, it doesn't work with other types of cputime accounting such as CONFIG_VIRT_CPU_ACCOUNTING_* where cputime_t can map to nsecs or any granularity preffered by the architecture. For example we get a buggy zero delta on full dyntick configurations: cat /sys/devices/system/cpu/cpuX/cpufreq/stats/time_in_state 2301000 0 2300000 0 [...] Fix this with using the proper jiffies_64_t to clock_t conversion. Reported-and-tested-by: Carsten Emde Signed-off-by: Andreas Schwab Signed-off-by: Frederic Weisbecker Acked-by: Paul E. McKenney Signed-off-by: Rafael J. Wysocki --- 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 04452f026ed0..4cf0d2805cb2 100644 --- a/drivers/cpufreq/cpufreq_stats.c +++ b/drivers/cpufreq/cpufreq_stats.c @@ -74,7 +74,7 @@ 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; } -- 2.20.1