Re: Attempted summary of suspend-blockers LKML thread

Mikael Abrahamsson
2010-08-01T06:49:43Z

On Sun, 1 Aug 2010, Mikael Abrahamsson wrote:

> it's just that mobile (low power) wasn't the intended target of the
> application when it was written, and this commonly shows.

I have another aspect I just thought about. I work for a telephony
company. We provide Internet connectivity throught various means, DSL,
Ethernet to the Home, mobile etc.

For ETTH and DSL, network usage is pretty straight forward, you send
packets, they get delivered pretty quickly with low marginal cost per
packet. For mobile, this is not quite so simple. Mobile networks are
designed for terminal/UE (user equipment) to use low power, so they go
down in low power state after a while. Let's take the case of 3G/HSPA:

After a short while (second) of idleness (no packets being sent), the
mobile network negotiates away the high speed resources (the one that
enables multimegabit/s transfers) and tries to give it to someone else.
After approximately 30 seconds, the terminal goes to "idle", meaning it
has no network resources at all. Next time it wants to send something (or
the network wants to deliver something to it), network resources need to
be negotiated again. This can take 1-2 seconds and uses battery power of
course. It also consumes resources in the operator network (because
mobility control units need to talk to base stations, tunnels need to be
re-negotiated etc).

Anyhow, my point is that not only is there a benefit in having multiple
applications wake up at the same time for power reasons within the device,
there is also a point in having coordination of their network access. If a
device is running 3 IM programs at the same time, it'd be beneficial if
they were coordinated in their communication with their Internet servers.
Same goes for the "check for new email" application. If they all were
optimized to only wake up the network connectivity once every 180 seconds
instead of doing it when the individual application felt like it, power
and other resources would be saved by all involved parties.

--
Mikael Abrahamsson email: swmike@swm.pp.se