Re: [PATCH 1/9] sched: add schedule_timeout_idle()

Peter Zijlstra
2016-03-22T21:24:07Z

On Tue, Mar 22, 2016 at 01:56:26PM -0400, Johannes Weiner wrote:
> On Tue, Mar 22, 2016 at 02:22:49PM +0100, Peter Zijlstra wrote:
> > On Tue, Mar 22, 2016 at 02:08:23PM +0100, Michal Hocko wrote:
> > > On Tue 22-03-16 13:51:13, Peter Zijlstra wrote:
> > > If that sounds like a more appropriate plan I won't object. I can simply
> > > change my patch to do __set_current_state and schedule_timeout.
> >
> > I dunno, I just think these wrappers are silly.
>
> Adding out-of-line, exported wrappers for every single task state is
> kind of silly. But it's still a common operation to wait in a certain
> state, so having a single function for that makes sense. Kind of like
> spin_lock_irqsave and friends.
>
> Maybe this would be better?:
>
> static inline long schedule_timeout_state(long timeout, long state)
> {
> __set_current_state(state);
> return schedule_timeout(timeout);
> }

Probably. However, with such semantics the schedule*() name is wrong
too, you cannot use these functions to build actual wait loops etc.

So maybe:

static inline long sleep_in_state(long timeout, long state)
{
__set_current_state(state);
return schedule_timeout(timeout);
}

might be an even better name; but at that point we look very like the
msleep*() class of function, so maybe we should do:

long sleep_in_state(long state, long timeout)
{
while (timeout && !signal_pending_state(state, current)) {
__set_current_state(state);
timeout = schedule_timeout(timeout);
}
return timeout;
}

Hmm ?