Re: Attempted summary of suspend-blockers LKML thread

Alan Stern
2010-08-01T22:16:57Z

On Sun, 1 Aug 2010, Paul E. McKenney wrote:

> > I should have made a stronger point: "power-aware" is _not_ a good
> > term for these applications. "power-enabled" would be better but
> > still not ideal. Maybe "power-permitted"? The definition is that
> > they are _permitted_ to do something (acquire suspend blockers), not
> > that they actually _do_ something.
>
> How about "PM-driving applications", as Rafael suggested?

Perhaps. But it's a little misleading, since what these applications
are permitted to do is to _prevent_ the system from going to low power.
So in a real sense they don't drive PM -- they block it. (Indeed,
that's what inspired the name "suspend blocker".) Of course, the same
objection applies to "power-permitted".

> > I was agreeing with the requirement but disagreeing with the reason
> > given for it. Even when buffers are large enough that the danger of
> > overrunning them is infinitesimal, delays in input event delivery are
> > still undesirable.
> >
> > Besides, the Android kernel doesn't vary its behavior based on whether
> > the recipient is power-permitted or power-naive; it _always_ delivers
> > input events in a timely fashion.
>
> True, the difference between the two classes of applications is in
> whether or not the application is permitted to process the event.
>
> I added "and to minimize response latencies" to the requirement.
> Does that capture it?

Yes.

> > > But leaving that aside, I thought that Arve and Brian explicitly
> > > stated this as a requirement on power-aware applications -- one of the
> > > responsibilities that came with the power to block suspend.
> >
> > No. There are _no_ requirements on power-permitted (or power-aware if
> > you prefer) applications, other than that the user decides to give it
> > the appropriate permission.
> >
> > Internally, of course, Android may enforce this rule on their own
> > software. But it has no force in regard to external applications.
>
> So should this be moved to a new "ANDROID POLICY" section or some such?

Or DESIRED BEHAVIOR, or some such.

Alan Stern