#9535 HIGH 10.1.3: need multicast group wakeups using the 8686 for wake-on-wlan vs collaboration

[Zarro Boogs per Child]

#9535: need multicast group wakeups using the 8686 for wake-on-wlan vs
collaboration
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           Reporter:  cjb     |       Owner:  dsaxena      
               Type:  defect  |      Status:  new          
           Priority:  high    |   Milestone:  10.1.3       
          Component:  kernel  |     Version:  not specified
         Resolution:          |    Keywords:               
        Next_action:  design  |    Verified:  0            
Deployment_affected:          |   Blockedby:               
           Blocking:          |  
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Comment(by martin.langhoff):

 "how is this solution different from simply disabling power management?"

 Simple!

 If we just disable power mgmt (when Salut is in use), we are awake all the
 time. Given that a laptop "alone under a tree" (ie: no AP in sight...)
 auto-tunes to adhoc 1 (mimicking auto-tuning to mesh 1 in earlier
 releases) and to Salut (as it won't find an XMPP server), then the most
 common situation for a laptop has it fully awake and burning power, for no
 good reason.

 With the patch I propose, power mgmt stays on, and we save battery. In a
 perfectly quiet RF environment, we save lots of battery. Same on a mostly
 quiet network.

 If we see mcast or ucast frames we wake up briefly -- this means that
 presence announcements are received ok, and that if we are in a collab
 session we stay in sync with other nodes. So the Salut-is-broken-with-
 power-mgmt-on situation is avoided completely.

 If the laptop is on a very busy infra or ad-hoc network, where other XOs
 are sending mcast frames, we'll stay awake longer. If it's busy enough
 with mcast frames, we'll stay awake all the time.

 This gradual effect is a significant win: we save power in many/most
 cases, and Salut doesn't break.

 The only not-nice scenario is that a busy Salut collab session between A
 and B will keep C, D and E awake. So multicast group wakeups _are_ still
 the right fix. But my patch (with improvements as you've suggested) is the
 best workaround so far, by a large margin.

-- 
Ticket URL: <http://dev.laptop.org/ticket/9535#comment:47>
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