RFC: better timer interface

[David Laight]

From: Thomas Gleixner
> Sent: 23 May 2017 12:59
> On Tue, 23 May 2017, David Laight wrote:
> 
> > From: Thomas Gleixner
> > > Sent: 21 May 2017 19:15
> > ...
> > > > timer_start(timer, ms, abs)
> > >
> > > I'm not even sure, whether we need absolute timer wheel timers at
> > > all, because most use cases are relative to now.
> >
> > Posix requires absolute timers for some userspace calls
> > (annoying because the code often wants relative).
> 
> Posix is completely irrelevant here. These timers are purely kernel
> internal.

Somehow pthread_cond_timedwait() has to be implemented.
Doing so without kernel timers that use absolute 'wall clock' time is tricky.

	David