On 09/26/2018 01:38 AM, Johannes Berg wrote:
On Tue, 2018-09-25 at 16:12 -0700, Ben Greear wrote:
While testing out some other issue, I noticed that my ath10k system creates
several hundred null-data probes when I abruptly down the AP the station
is connected to.
I guess this is because I use the mac80211 stack to handle the probes, and
the firmware then retries each mac80211 probe many times.
So, in the case where mac80211 is sending a null-data probe, is the assumption
that the driver will try each frame exactly once?
Not really, it should be treated like any other management frame.
Or is several hundred frames expected? I'm guessing the former, but before I go
hacking firmware, I thought I would ask...
Certainly not several hundred, but maybe a dozen? I think iwlwifi uses
16, and minstrel would set up max_rate_tries, which drivers set to
somewhere between 1 and 18? One seems s a bit low, mt76?
johannes
I have been running with mac80211/mlme.c's max_nullfunc_tries set to 5 for many years.
Long ago it helped with connectivity issues with lots of vdevs and and/orloaded APs
if I recall correctly.
In fact, I see 62 frames captured on air all with the same sequence number
in the test I just did, and subsequent frames with the next seq-no are sent
immediately after the first one. The frames are all right after each other, so
I guess this is probably firmware doing lots of HW retransmits and then *also*
doing software retransmits in the firmware (my reading of mlme.c indicates it should
only probe every 500ms).
I think I'll start by making sure the firmware does not do software retransmits
for frames from the driver (self-gen frames are OK to be retransmitted I guess).
Thanks,
Ben
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
