On Tue, 2009-12-01 at 09:01 +0200, Kalle Valo wrote: > Johannes Berg <johannes@xxxxxxxxxxxxxxxx> writes: > > > Add spatial multiplexing power save configuration > > hooks to cfg80211/nl80211. > > Is it really necessary to export this to user space, at least via > nl80211? If we add this to nl80211, we have to support this almost > forever. > > Also how are planning to use this? What components will use the > interface and how? Good questions. > My concern here is that we will end up having, yet again, complicated > user space interface for power save. The ideal situation would be that > kernel would configure all this automatically and we would have a > simple interface just to disable power save in cases where it doesn't > work (broken APs etc). I'm not actually sure that there are APs broken wrt. SM PS, it seems highly unlikely -- even if there are (like mac80211!!) the rate control algorithm would recover the situation. As such, I suppose it's somewhat a debugging API. On the other hand, there are actual traffic throughput consequences of enabling SM PS, even when in powersave. Powersave will be turned off automatically if there's enough traffic, but SM PS won't. The default, automatic, means it just follows powersave (dynamic SM PS if on, no SM PS if off), but I'm not sure that is typically desirable. Of course, on the other hand, I don't see many users actually setting it. An alternative could be to try to estimate traffic, but that gets messy fairly quickly because the thresholds depend on the environment. If you prefer to leave it out for now, I can probably move it to debugfs until we have a more clearly defined use case, although if we decide that we never want it then obviously the action frame handling can go away again. johannes
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