Issues with power management inhibition

[Fabian Köster]

Hello,

I discovered some issues on the Xfce desktop when it comes to usability
regarding power management.

For a good power management it is essential that it does not annoy the
user. Otherwise he is frustrated and turns it off entirely - not good
for low power consumption.

I see three scenarios where power management should be inhibited
automatically:

1.) Video playback
2.) Audio playback
3.) Long-running maintenance tasks like package upgrades, filesystem
    checks etc.

In the 1.) scenario the power management should be inhibited entirely:

* Disable Screensaver
* Disable Monitor Dimming
* Disable Monitor standby/power off
* Disable system standby

Nevertheless, the system may dynamically reduce its power consumption
by downclocking, slowing hard disks etc.

The 2.) scenario only requires to disable system standby.

The 3.) scenario has same requirements as the 2.)

===========================
==== Concrete Problems ====
===========================

On my test systems (Gentoo Linux and Xubuntu 11.10) I was not able to
realize the 1.) scenario.

== Totem ==

Totem only disables gnome-screensaver. 

Missing:

* Disable Monitor Dimming
* Disable Monitor standby/power off
* Disable system standby

== Parole ==

Parole only disables system standby

Missing:

* Disable Screensaver
* Disable Monitor Dimming
* Disable Monitor standby/power off


===========================
==== Possible solutions ===
===========================

I noticed that system standby can be inhibited via the
D-Bus interface /org/freedesktop/PowerManagement/Inhibit. This is
sufficient for applications in scenarios 2.) and 3.) and is what Parole 
is doing.

For scenario 1.) I could not find a full solution like above. There is
the xdg-screensaver tool from xdg-utils and
the /org/gnome/ScreenSaver/Inhibit interface for disabling the
screensaver, but not for disabling monitor dimming or monitor standby.
And there are also currently some bugs preventing a cross-desktop
solution for inhibiting the screensaver [1][2][3].

Also the proposed standardized /org/freedesktop/ScreenSaver
interface does not provide a solution for disabling monitor standby.

An extended version of the /org/freedesktop/PowerManagement/Inhibit
approach would be nice, allowing applications to inhibit single
power management features. 

Or am I missing something?

Fabian

[1] https://bugs.launchpad.net/ubuntu/+source/xdg-utils/+bug/497318
[2] https://bugzilla.gnome.org/show_bug.cgi?id=579430
[3] https://bugs.launchpad.net/gnome-screensaver/+bug/428884/
[4] http://lists.freedesktop.org/archives/xdg/2009-April/010317.html