#10363 NORM 10.1.3: Auto-Suspend gets in the way when sharing over Salut

[Tomeu Vizoso]

On Thu, Sep 23, 2010 at 15:30, Tomeu Vizoso <tomeu at tomeuvizoso.net> wrote:
> On Mon, Sep 20, 2010 at 12:56, Paul Fox <pgf at laptop.org> wrote:
>> tomeu wrote:
>>  > On Thu, Sep 16, 2010 at 23:38, Martin Langhoff
>>  > <martin.langhoff at gmail.com> wrote:
>>  > > On Thu, Sep 16, 2010 at 5:05 AM, Tomeu Vizoso <tomeu at tomeuvizoso.net> wrote:
>>  > >> So the problem is that if you had to resync all state for each machine
>>  > >> every time they wake up, you would use lots of bandwidth with the
>>  > > (...)
>>  > >> Another issue with this is that you not only want to resync presence,
>>  > >> but shared activities also would need to resync their state.
>>  > >
>>  > > Correct. My notes on the bug are probably unreadable -- it was late
>>  > > last night, apologies.
>>  > >
>>  > > What I mean to say is that we could
>>  > >
>>  > > 1 - explore the interaction between sleep timeouts and Salut resync
>>  > > frequency for presence
>>  > >
>>  > > 2 - hack the Tubes/Telepathy stack to _prevent sleep_ while an actual
>>  > > collaboration session is running
>>  > >
>>  > > I think #1 needs to be done regardless, as it'll improve behaviour
>>  > > even if/when we our networking/suspend issues sorted. And some of the
>>  > > issues in network/suspend interaction won't be easy to resolve.
>>  >
>>  > I doubt there's much that can be done in Salut about it, should be
>>  > instead done inside Avahi. I would see how mDNS works, then look for
>>  > opportunities of tuning knobs in Avahi to speed up rediscovery:
>>  >
>>  > http://tools.ietf.org/html/draft-ietf-dnsext-mdns-47
>>  >
>>  > I'm going to ask around in case somebody has already thought of it and
>>  > can provide a shortcut.
>>
>> the laptop knows how long it was suspended, and this information could
>> be made available to a resume hook (which almost exists, but not
>> quite, in powerd) if it would be useful.  i.e., a a post-resume script
>> could decide whether to kick the protocols to do something differently,
>> if that was needed.
>
> Paul, what do you think about powerd implementing org.freedesktop.UPower ?
>
> http://upower.freedesktop.org/docs/UPower.html

If so, Lennart could be interested in accepting a patch that makes
Avahi listen for Resuming() and that implements the wake-up behavior
as specified in
http://files.multicastdns.org/draft-cheshire-dnsext-multicastdns.txt .

After a quick read, looks like it would involve querying the network
with the QU bit set so the other nodes can send unicast replies
instead of multicast, thus saving bandwidth.

Regards,

Tomeu

> Regards,
>
> Tomeu
>
>> paul
>> =---------------------
>>  paul fox, pgf at laptop.org
>>
>