Johannes Berg <johannes@xxxxxxxxxxxxxxxx> writes: > On Wed, 2008-11-05 at 22:27 +0200, Kalle Valo wrote: >> I'm working on implementing the "dynamic Power Save" (ie. PS enabled >> after an idle period) feature to mac80211. Here are my current >> thoughts: >> >> First of all, I think we should enable CONF_PS only when associated. >> So instead of directly calling hw_config() from >> ieee80211_ioctl_siwpower() we should do that only when associated. >> Otherwise we change it only after association or disassociation. This >> means that we have to add a separate bit/variable for storing what >> user has requested. > > Totally agreed. Good :) >> PS should be disabled while associated and running software scan, and >> naturally re-enabled after the scan has finished. I assume hardware >> scanning implementations are clever enough to disable PS when scanning >> and we don't have to worry about that case. > > And on that too. And should there be a monitor flag that disables PS, so > that we can "refcount" the PS bit in a way? Sorry, I don't follow you here. What do you mean by a monitor flag? >> The dynamic PS implementation is still a bit open issue for me. I have >> been thinking something like that in tx.c frames will be queued if PS >> is enabled, PS will be disabled in a workqueue by calling >> ieee80211_hw_config() and only after that the queued frames are >> transfered. So something similar as sta->ps_tx_buf does in AP mode. No >> idea if this is feasible or not. > > Not sure I understand the dynamic PS yet. Basically the idea is to disable PS whenever we are transmitting (and maybe also receiving, don't know yet) frames, but whenever there's a long enough idle period PS would be enabled again. So in principle this would be a compromise of low power consumption and low latency. Naturally the idle period would be configurable with siwpower() and whatever nl80211 equivalent we will have in future. > Why would you queue up frames? To reduce the number of radio wakeups > when TX traffic is low? Just because I assume that invoke_tx_handlers() cannot sleep but ieee80211_hw_config() sleeps. I didn't think of any other way to solve this, but I haven't thought that much about this. What do you think? -- Kalle Valo -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
