#9048 HIGH Not Tri: Wireless scanning causes network pauses

[Zarro Boogs per Child]

#9048: Wireless scanning causes network pauses
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           Reporter:  johnf      |       Owner:  mbletsas        
               Type:  defect     |      Status:  new             
           Priority:  high       |   Milestone:  Not Triaged     
          Component:  wireless   |     Version:  not specified   
         Resolution:             |    Keywords:  scan packet loss
        Next_action:  never set  |    Verified:  0               
Deployment_affected:  Australia  |   Blockedby:                  
           Blocking:             |  
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Comment(by annaneal):

 I have prepared a patch.

 Upon investigation I found that netif_carrier_off/on is causing the
 interface to be brought down during each scan.  It is not necessary to
 bring
 down the interface to stop it from transmitting during a scan.  The
 netif_stop_queue command is used for this.  The netif_wake_queue command
 will
 need to be called to make sure the queue wakes up and transmits anything
 that
 has been waiting.

 Removing the netif_carrier_off/on calls will leave the packet buffering up
 to
 the kernel.  This means that if the buffer fills up, some packets may
 still be
 lost.  Because the scan takes a short amount of time this should not cause
 too
 much interruption.

 In addition, when looking at other device drivers and the mac80211
 stack the carrier is never turned off during a scan.

 After removing the netif_carrier_off/on calls in the scan routine tests
 show
 that only one packet is lost at every other scan.  This is in contrast to
 a
 consistent 8 packet loss on every scan.

 I have attached a patch to this ticket.  In this patch I removed the
 carrier_off/on calls.

 Anna

-- 
Ticket URL: <http://dev.laptop.org/ticket/9048#comment:18>
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