Re: [RFC] Improve software scan timing

[Johannes Berg <johannes@sipsolutions.net>]

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On Tue, 2010-02-23 at 16:19 +0100, Helmut Schaa wrote:

> However I've got a few open questions:
> 
> Does anybody know if pm_qos is already used by any applications? At
> least on my system it seems that nothing sets any latency requirements.

Yeah, it doesn't seem to be used...

> Should we also consider the current listen_interval for deciding how
> long
> we could stay away from the operating channel? That should prevent us
> from losing too many frames but since most drivers don't register a
> max_listen_interval we usually end up with a listen_interval of
> 1 which is quite short (which means only scanning one channel in a
> row).
> 
> Kalle, Johannes, how is the listen_interval handled in the powersave
> code?
> Are we only sleeping for one beacon interval or are we ignoring the
> listen_interval currently.

I figured this listen interval stuff would come back to bite us at some
point. I don't think we should negotiate a listen interval of 1. OTOH,
I'm not convinced that all APs would reject it with a status code of 51
if it's too large? Or is that tested anywhere like WFA?

In any case, right now the powersave code pretty much ignores it,
although that's not really a good plan.

johannes

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