Re: [PATCH 2/2] Use ktime_get() instead of sched_clock() for blkiocgroup stats.

From: Ingo Molnar
Date: Sat Jun 12 2010 - 03:19:23 EST

* Divyesh Shah <dpshah@xxxxxxxxxx> wrote:

> This will take care of the pre-emptive kernel issue and the unbounded
> TSC drift problem. We will lose resolution though in some cases.

> - blkg->stats.start_group_wait_time = sched_clock();
> + blkg->stats.start_group_wait_time = ktime_to_ns(ktime_get());


ktime_get() can have insanely high overhead. Peter has added local_clock(), if
then you should use that and apply checks to make sure the result isnt

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