Re: [RFC v3] mac80211: Optimize scans on current operating channel.

[Ben Greear <greearb@candelatech.com>]

On 01/31/2011 05:56 AM, Johannes Berg wrote:
>
>>> However -- I was thinking of something else, not data packets. While
>>> scanning, all received beacons will be handed to the scan code. But if
>>> the mlme code isn't told to stop looking for them, it'll still expect to
>>> see the beacons.
>>
>> Currently, it seems mlme timers are stopped when we start scanning,
>> and then started when scanning is complete.
>
> Ok, I wasn't quite sure about that part -- whether it happened when
> going off-channel or when starting scan. If it happened while going
> off-channel this would've been problematic here.
>
>> However, I don't see any similar effort in the work_work() method
>> when it goes off-channel.
>>
>> Should we move the timer pause&  restart logic into the offchannel_stop_vifs
>> and offchannel_return methods?
>
> Well, sort of no, and sort of yes -- both will disrupt that code in a
> sense, but even scanning on the same channel will disrupt it due to the
> beacon diversion, unless we copy the beacons and give them to both sides
> (scan and mlme)?

Seems to me both sides should get them.  I'll try to figure out how to
do that properly today.

But, if work_work() takes us off-channel often enough, wouldn't that
cause undue beacon loss and/or timed-out tx acks?  Are there any guarantees
about how often and how long work_work() can take us off-channel?

Thanks,
Ben

>
> johannes


-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com