Auto-suspend and Presence Service

[Greg Smith]

Hi John,

Thanks for the comments and early catch on this.

Robert and wireless/collaboration experts,

Can you comment on this?

There are a couple of relevant requirements and known issues documented 
here: http://wiki.laptop.org/go/Feature_roadmap/Improved_battery_life

It sounds like we need a solid design proposal which defines exactly 
how/when the wireless uses power and how/when the XO wakes up. Any links 
or suggestions welcome.

Thanks,

Greg S

John Gilmore wrote:
> In 9.1.0, auto-suspend is going to be on by default, which we estimate
> will roughly triple our battery life.  We're working on fixing all the
> bugs that would prevent that.
> 
> One of them is not strictly a bug -- it's a performance issue.  The
> Presence Service sends packets frequently, for tracking the presence
> of your friends and any shared activities.  Many of these are
> multicast packets (some are probably unicast jabber packets, too).
> 
> In 8.2.0, with auto-suspend enabled, you have to run a specific command
> to enable suspended laptops to awaken when multicast packets arrive;
> see bug #6818 and run "ethtool -s msh0 wol um".  This will become the
> default in 9.1.0.
> 
> The problem I can foresee is that the Presence Service will send 
> packets so frequently that everyone's laptop will always be waking up,
> negating the power-stretching abilities of auto-suspend.  This seems
> to occur with only a few laptops around (in my tests at home); yet
> we need to make it work with dozens of laptops within range, for
> our deployments.
> 
> I hope that the Collabora team is running in this mode now, and
> working out ways to reduce packet traffic to let sleeping laptops lie.
> The cellular phone industry went through several cycles of design
> improvements like this, enabling today's remarkable phone battery
> life, without impact on our ability to rapidly communicate whenever
> desired.  OLPC hasn't yet done the first round of such improvements,
> and I hope it WILL do so before 9.1.0.  We could all use those long
> battery lives -- especially the kids in the rural deployments.  We
> don't want to tell them to turn off collaboration if they want their
> laptop to last all day; it's one of our key features.
> 
>         John
> 
> 
> 
>