[Pm-utils] low power mode

[David Zeuthen]

On Mon, 2006-05-01 at 19:17 +0100, Matthew Garrett wrote:
> (I think several of the powersave "powersave" and "performance" 
> distinctions are bogus - we can do better than that by figuring out 
> what's actually needed rather than just having static configurations 
> that mostly just serve to give the user more buttons to press, 

As I've argued elsewhere in the thread there really is a good reason to
give users at least one extra button

 [ ] Sacrifice performance for energy saving

buried deep in e.g. gnome-power-preferences as Bob and Alice have
different concepts regarding "quality" and battery/performance trade
offs. Sure, most of the Alice's and Bob's of the world might not care
but some will and we shouldn't alienate those "just because we know
better"...

Btw, I don't think it's a huge usability cost as it's many clicks away -
and if we put the option in the tray icon (and I think we should) it
should be accompanied by a scary dialog that thoroughly explains the
user what will happen; e.g. 

 +---------------------------------------------------------+
 | Your battery will run out faster if you decide not to   |
 | sacrifice performance for battery savings.              |
 |                                                         |
 | Only resource intensive applications like media players |
 | and kernel compiles* benefit from changing this. Most   |
 | applications are not affected.                          |
 |                                                         |
 | [ ] Set this as default when running on battery         |
 |                                                         |
 |                  [Cancel] [Don't sacrifice performance] |
 +---------------------------------------------------------+
 

* : ok, kidding, someone please reword :-)


> and 
> "powersave" against "performance" just encourages the same sort of 
> binary thinking that led us to the dire speedstep situation on Windows 
> of "Oh look, my CPU goes really slowly now". Providing it doesn't cost 
> us usability, we should *always* be saving power. And that requires us 
> to learn from the embedded guys that have actually solved this problem 
> properly - can you imagine how pissed off people would get if their PDA 
> only had the same sort of functionality?)

I think this is largely going to be interesting in the application
space; e.g. we actually do need GStreamer to have performance-
configurable codecs in order for e.g. Totem to do anything intelligent
about this. Does anyone know the status of that?

And, btw, this is slightly off topic for pm-utils - I think the main
point is that the 1) power management daemon; and 2) the apps should be
intelligent about this. And that it makes sense to give the user this
preference. It's just whether the daemon decides to invoke
pm-setlowpower e.g. SetLowPower() on HAL.

    David