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| author | Arjan van de Ven <arjan@linux.intel.com> | 2010-05-09 08:22:08 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-05-09 19:35:25 +0200 |
| commit | b1f724c3055fa75a31d272222213647547a2d3d4 (patch) | |
| tree | 9f9e9105a01405e252b5214e83bdbfcd10921f43 /kernel/time | |
| parent | e7858f52a5cb868289a72264534a1f05f3340c6c (diff) | |
| download | linux-b1f724c3055fa75a31d272222213647547a2d3d4.tar.bz2 | |
sched: Add a comment to get_cpu_idle_time_us()
The exported function get_cpu_idle_time_us() has no comment
describing it; add a kerneldoc comment
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: davej@redhat.com
LKML-Reference: <20100509082208.7cb721f0@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/tick-sched.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index f25735a767af..358822ee32d5 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -179,6 +179,20 @@ static ktime_t tick_nohz_start_idle(struct tick_sched *ts) return now; } +/** + * get_cpu_idle_time_us - get the total idle time of a cpu + * @cpu: CPU number to query + * @last_update_time: variable to store update time in + * + * Return the cummulative idle time (since boot) for a given + * CPU, in microseconds. The idle time returned includes + * the iowait time (unlike what "top" and co report). + * + * This time is measured via accounting rather than sampling, + * and is as accurate as ktime_get() is. + * + * This function returns -1 if NOHZ is not enabled. + */ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) { struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |