Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)

Peter Zijlstra
2010-05-27T17:13:11Z

On Thu, 2010-05-27 at 18:07 +0100, Matthew Garrett wrote:
> On Thu, May 27, 2010 at 07:04:38PM +0200, Thomas Gleixner wrote:
> > On Thu, 27 May 2010, Matthew Garrett wrote:
> > > Sure, if you're not using opportunistic suspend then I don't think
> > > there's any real need for the userspace side of this. The question is
> > > how to implement something with the useful properties of opportunistic
> > > suspend without without implementing something pretty much equivalent to
> > > the userspace suspend blockers. I've sent another mail expressing why I
> > > don't think your proposed QoS style behaviour provides that.
> >
> > Opportunistic suspend is just a deep idle state, nothing else.
>
> No. The useful property of opportunistic suspend is that nothing gets
> scheduled. That's fundamentally different to a deep idle state.

I think Alan and Thomas but certainly I am saying is that you can get to
the same state without suspend.

Either you suspend (forcefully don't schedule stuff), or you end up
blocking all tasks on QoS/resource limits and end up with an idle system
that goes into a deep idle state (aka suspend).

So why isn't blocking every task on a QoS/resource good enough for you?