Re: [PATCH] hrtimers: Special-case zero length sleeps

Matthew Garrett
2012-02-15T20:22:24Z

On Wed, Feb 15, 2012 at 09:14:30PM +0100, Thomas Gleixner wrote:

> Just for the extended fun of it: The pre hrtimer implementation in
> Linux put the task on sleep as well up to the next jiffies boundary,
> so anything which used sleep(0) on a pre hrtimer kernel was going to
> sleep. That's also the case today when high resolution timers are
> disabled (compile or runtime).
>
> So anything which relies on sleep(0) as a fast scheduling point is and
> has been broken forever.

Excellent. So the real question is what /should/ sleep(0) do - nothing,
schedule or sleep for an arbitrary period of time that could be years?

--
Matthew Garrett | mjg59@srcf.ucam.org