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sched: Provide iowait counters

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For counting how long an application has been waiting for
(disk) IO, there currently is only the HZ sample driven
information available, while for all other counters in this
class, a high resolution version is available via
CONFIG_SCHEDSTATS.

In order to make an improved bootchart tool possible, we also
need a higher resolution version of the iowait time.

This patch below adds this scheduler statistic to the kernel.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4A64B813.1080506@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Arjan van de Ven
2009-07-20 11:26:58 -07:00
committed by Ingo Molnar
parent f14eff1cc2
commit 8f0dfc34e9
4 changed files with 17 additions and 0 deletions
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5
kernel/sched_fair.c
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@@ -652,6 +652,11 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
se->sum_sleep_runtime += delta;
if (tsk) {
if (tsk->in_iowait) {
se->iowait_sum += delta;
se->iowait_count++;
}
/*
* Blocking time is in units of nanosecs, so shift by
* 20 to get a milliseconds-range estimation of the