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

[Ingo Molnar]

* 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());

Ugh!

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 
negative.

	Ingo
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