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sched: Add a comment to get_cpu_idle_time_us()

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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>
This commit is contained in:
Arjan van de Ven 2010-05-09 08:22:08 -07:00 committed by Ingo Molnar
parent e7858f52a5
commit b1f724c305
1 changed files with 14 additions and 0 deletions
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14
kernel/time/tick-sched.c
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@ -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);