Re: [PATCH/RFC] wait_for_completion_timeout() considered harmful.

From: Ingo Molnar
Date: Tue Nov 19 2013 - 02:06:07 EST



* Jonathan Corbet <corbet@xxxxxxx> wrote:

> On Tue, 19 Nov 2013 00:42:09 +0100
> Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> > I briefly talked to Thomas about this earlier today and we need to
> > fix this at a lower level -- the quick 'n dirty solution is to add
> > 1 jiffy down in the timer-wheel when we enqueue these things.
>
> That can lead to situations like the one I encountered years ago
> where msleep(1) would snooze for 20ms. I didn't get much love for
> my idea of switching msleep() to hrtimers back then, but I still
> think it might be be better to provide the resolution that the
> interface appears to promise.

That looks like a sensible approach - mind resending that patch? We
can put it into the timer tree and see what happens.

Thanks,

Ingo
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