On 09/19/2011 10:40 PM, Dave Taht wrote: > On Mon, Sep 19, 2011 at 11:38 AM, Kalle Valo <kvalo@xxxxxxxxxxxxxxxx> wrote: >> When pinging form ar6003 to the AP RTT was high even when power save was >> disabled: >> >> 100 packets transmitted, 97 received, 3% packet loss, time 99125ms >> rtt min/avg/max/mdev = 1.875/46.733/795.506/139.181 ms >> >> After some investigation one reason for this was that received >> multicast traffic confused the aggrecation logic and caused 400 ms >> timeouts when receiving multicast frames from AP. >> >> A simple way to fix is to pass only unicast frames for aggregation. This >> improves RTT: >> >> 100 packets transmitted, 99 received, 1% packet loss, time 99144ms >> rtt min/avg/max/mdev = 2.083/13.084/403.390/56.794 ms > > I note that while the improvement above is enormous, a 403ms RTT for > a packet is the rough equivalent of a detour around all of planet Earth... > between your couch and the AP. That's because firmware doesn't disable 802.11 power save when I ping with one second interval. Apparently it needs two frames within ~200 ms to disable power save. > Can outliers of this sort be improved? Definitely. I just want to fix serious bugs first, like the one above. > At what point are packets dropped? I'm guessing that the power save has issues and drops packets occasionally. I haven't investigated it yet. Kalle -- 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
