On 01/29/2018 01:47 PM, Toke Høiland-Jørgensen wrote:
Ben Greear <greearb@xxxxxxxxxxxxxxx> writes:
On 01/27/2018 05:11 AM, Toke Høiland-Jørgensen wrote:
Ben Greear <greearb@xxxxxxxxxxxxxxx> writes:
I'm doing a test with 200 virtual stations on each of 6 ath9k radios.
When I configure stations for DHCP, I see cases where stations on a particular
radio will not transmit anything sometimes. I see no 'XMIT' logs that show indication of
frames being received in the driver from the upper stack, but if I use 'tshark' on
a station interface, it shows frames being 'transmitted'.
I do, however, see this, which looks like it might show
an issue. It looks like whatever 'aqm' is, it has an ever expanding number
of backlog packets:
The aqm is the intermediate queues in mac80211. So this indicates that
the driver is not pulling packets for transmission.
With that many stations, I wonder whether it is due to the airtime
fairness scheduler throttling the station? What is the contents of
debug/ieee80211/wiphy2/netdev\:sta30194/stations/00\:0e\:8e\:69\:b8\:f7/airtime
while the station is not transmitting? And is it all stations on that
particular radio, or only some of them?
Here is the output of airtime and aqm on a hung station:
# cat /debug/ieee80211/wiphy0/netdev\:sta10057/stations/00\:0e\:8e\:50\:74\:8a/airtime
RX: 83706 us
TX: 4202 us
Deficit: VO: 198 us VI: 300 us BE: -8306 us BK: 300 us
Right. This looks like incoming traffic is depleting the airtime quantum
faster than it can be replenished by the scheduler, which means that the
station gets completely starved.
Could you try turning off the airtime scheduler?
echo 0 > /sys/kernel/debug/ieee80211/wiphy0/ath9k/airtime_flags
and see if the problem goes away.
If it does, please check if the problem persists when setting
airtime_flags to 1 (which means only include TX airtime).
-Toke
That did not seem to help:
# cat /debug/ieee80211/wiphy0/netdev\:sta10058/stations/00\:0e\:8e\:50\:74\:8a/node_aggr
Max-AMPDU: 65535
MPDU Density: 8
TID SEQ_START SEQ_NEXT BAW_SIZE BAW_HEAD BAW_TAIL BAR_IDX SCHED HAS-QUED
0 0 0 64 0 0 -1 1 1
# cat /debug/ieee80211/wiphy0/netdev\:sta10058/stations/00\:0e\:8e\:50\:74\:8a/airtime
RX: 0 us
TX: 4682 us
Deficit: VO: 300 us VI: 300 us BE: 300 us BK: 300 us
# cat /debug/ieee80211/wiphy0/netdev\:sta10058/stations/00\:0e\:8e\:50\:74\:8a/aqm
target 49999us interval 299999us ecn no
tid ac backlog-bytes backlog-packets new-flows drops marks overlimit collisions tx-bytes tx-packets flags
0 2 2406 11 3 0 0 0 7 0 0 0x6(RUN AMPDU NO-AMSDU)
1 3 0 0 0 0 0 0 0 0 0 0x0(RUN)
2 3 0 0 0 0 0 0 0 0 0 0x0(RUN)
3 2 0 0 0 0 0 0 0 0 0 0x0(RUN)
4 1 0 0 0 0 0 0 0 0 0 0x0(RUN)
5 1 0 0 0 0 0 0 0 0 0 0x0(RUN)
6 0 0 0 0 0 0 0 0 0 0 0x0(RUN)
7 0 0 0 12 0 0 0 13 312 13 0x0(RUN)
8 2 0 0 0 0 0 0 0 0 0 0x0(RUN)
9 3 0 0 0 0 0 0 0 0 0 0x0(RUN)
10 3 0 0 0 0 0 0 0 0 0 0x0(RUN)
11 2 0 0 0 0 0 0 0 0 0 0x0(RUN)
12 1 0 0 0 0 0 0 0 0 0 0x0(RUN)
13 1 0 0 0 0 0 0 0 0 0 0x0(RUN)
14 0 0 0 0 0 0 0 0 0 0 0x0(RUN)
15 0 0 0 0 0 0 0 0 0 0 0x0(RUN)
Thanks,
Ben
--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc http://www.candelatech.com
