powerd-dbus network extension

[Sascha Silbe]

Excerpts from Daniel Drake's message of Wed Aug 03 21:39:55 +0200 2011:

> Good suggestion, I assume you are talking about
> http://people.gnome.org/~mccann/gnome-session/docs/gnome-session.html

As mentioned before [1], UPower provides related functionality [2]
that's better suited for automatic power management. Gnome-session seems
to be targeted at manual power management, i.e. explicitly suspending
the machine on a user request (and that's what it actually implements).

At least on Debian, the UPower API is unrestricted, so activities could
start to use it right away. It doesn't fit perfectly (you can only
register DMA latency and network throughput requirements), but better
than nothing. And unlike gnome-session UPower is a system daemon.

powerd-dbus could listen to LatencyChanged('network', ...). Not sure
what it would actually do with the value, though: It's a bandwidth
(Kbps) rather than a latency (µs). Should be worth a try asking the
UPower folks to add another metric, though - especially since one of the
use cases listed in the blog post [3] needs this: "I want my IM
application to request 0.5s latency for messages".

> Unfortunately it would be a lot of work to implement, because
> gnome-session implements this interface. We would have to rebase sugar
> around that.

I already have a patch to use upstream gnome-session instead of the
ancient copy we ship in sugar-toolkit. The only missing piece is API to
trigger Shutdown and Reboot [4] without gnome-session popping up a
dialog. With the upstream gnome-session, we benefit from their
accessibility work (=> automated UI testing).

Sascha

[1] http://lists.laptop.org/pipermail/devel/2010-April/028394.html
[2] http://upower.freedesktop.org/docs/QoS.html
[3] http://blogs.gnome.org/hughsie/2008/11/06/devicekit-power-latency-control/
[4] https://bugzilla.gnome.org/show_bug.cgi?id=575880
-- 
http://sascha.silbe.org/
http://www.infra-silbe.de/
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