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SubjectRe: [PATCH 1/7] sched: Update rq clock on nohz CPU before migrating tasks
From
2013/4/9 Peter Zijlstra <peterz@infradead.org>:
> On Sat, 2013-04-06 at 18:45 +0200, Frederic Weisbecker wrote:
>> Because the sched_class::put_prev_task() callback of rt and fair
>> classes are referring to the rq clock to update their runtime
>> statistics. A CPU running in tickless mode may carry a stale value.
>> We need to update it there.
>
> I'm failing to see how tickless makes a difference here.. we should
> never rely on a ->clock set at the last tick, that's wrong.

Ah I made that big mis-assumption then ;)

>
> So either explain which/how clock update gets lost by tickless or make
> it unconditional.

So most of those fixup need to be made unconditional I think.


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