linux-kernel - Re: [linux-pm] Attempted summary of suspend-blockers LKML thread

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Date:	Sun, 1 Aug 2010 18:11:48 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	James Bottomley <James.Bottomley@...e.de>
Cc:	Arjan van de Ven <arjan@...radead.org>, peterz@...radead.org,
	swetland@...gle.com, linux-kernel@...r.kernel.org,
	florian@...kler.org, linux-pm@...ts.linux-foundation.org,
	tglx@...utronix.de, alan@...rguk.ukuu.org.uk
Subject: Re: [linux-pm] Attempted summary of suspend-blockers LKML thread

On Sun, Aug 01, 2010 at 06:16:33PM -0500, James Bottomley wrote:
> On Sat, 2010-07-31 at 22:48 -0700, Paul E. McKenney wrote:
> > On Sat, Jul 31, 2010 at 09:52:14PM -0700, Arjan van de Ven wrote:
> > > On Sat, 31 Jul 2010 10:58:42 -0700
> > > "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> wrote:
> > > 
> > > > o	"Power-aware application" are applications that are permitted
> > > > 	to acquire suspend blockers on Android.  Verion 8 of the
> > > > 	suspend-blocker patch seems to use group permissions to
> > > > determine which applications are classified as power aware.
> > > > 
> > > > 	More generally, power-aware applications seem to be those that
> > > > 	have permission to exert some control over the system's
> > > > 	power state.
> > > 
> > > I don't like the term "Power aware application". An application is well
> > > behaved or it isn't. "aware" has nothing to do with it.
> > 
> > Applications are often complex enough to be aware of some things, naive
> > about others, well behaved in some ways, and ill-behaved in others.
> > This has been the case for some decades now, so it should not come as
> > a surprise.
> > 
> > I am of course open to suggestions for alternatives to the term "power
> > aware application", but most definitely not to obfuscating the difference
> > between power awareness (or whatever name one wishes to call it) and
> > the overall quality of the application, whatever "quality" might mean
> > in a given context.
> 
> So the reason everyone's having trouble with this definition is that it
> actually conflates two separate axes of power management.
> 
> There are good and bad applications in the power sense ... burns less vs
> burns more.
> 
> And there are user mandated vs user optional processes ...
> necessary/wanted vs unnecessary/unwanted.
> 
> What android actually does is reward well written applications because
> they "just work" and they don't have to be power aware at all ...
> they're usually event driven and split into the android
> provider/consumer model.
> 
> Badly written applications that are not suspend block aware get shut
> down (by system suspend) when the screen turns off, so they're also
> power/suspend unaware.
> 
> Applications that want to present the user with a choice in android are
> power/suspend aware because the only way they get to present the choice
> is via suspend blockers.
> 
> The "power problem" always devolves to resolving a set of choices around
> a given set of control axes.  The problem is that the set of control
> axes isn't unique and doesn't have a well agreed upon selection.  This
> makes it hard to make definitive terminology because you have to pick
> the set of axes (implicitly or explicitly) before defining terms ...

That does seem to be about the size of it...  :-/

							Thanx, Paul
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