Messages in this thread | | | From | Divyesh Shah <> | Date | Sat, 12 Jun 2010 08:51:54 -0700 | Subject | Re: [PATCH 2/2] Use ktime_get() instead of sched_clock() for blkio cgroup stats. |
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On Sat, Jun 12, 2010 at 12:18 AM, Ingo Molnar <mingo@elte.hu> wrote: > > * Divyesh Shah <dpshah@google.com> 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.
Ok. The negative checks are already in the code.
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