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authorAndreas Schwab <schwab@linux-m68k.org>2013-09-07 18:35:08 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-09-10 02:49:46 +0200
commita857c0b9e24e39fe5be82451b65377795f9538d8 (patch)
tree9a1338d24be24c358b2fb00e4cfcc2a5fa6b5b6a /drivers/cpufreq
parentcpufreq: serialize calls to __cpufreq_governor() (diff)
downloadlinux-a857c0b9e24e39fe5be82451b65377795f9538d8.tar.xz
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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 <C.Emde@osadl.org> Signed-off-by: Andreas Schwab <schwab@linux-m68k.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq_stats.c2
1 files changed, 1 insertions, 1 deletions
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;
}