IMX6Q Ethernet UDP Performance

[sonpham]

Hi All,

Two IMX6Q is connected through a gigabit switch and the following test was performed using iperf3 

Micrel KSZ9021 Gigabit PHY

Client:

iperf3 -u -c 10.88.22.22 -b 1G

Connecting to host 10.88.22.22, port 5201
[ 5] local 10.88.11.11 port 55031 connected to 10.88.22.22 port 5201
[ ID] Interval Transfer Bitrate Total Datagrams
[ 5] 0.00-1.00 sec 42.5 MBytes 357 Mbits/sec 30787
[ 5] 1.00-2.00 sec 42.5 MBytes 357 Mbits/sec 30786
[ 5] 2.00-3.00 sec 42.5 MBytes 357 Mbits/sec 30779
[ 5] 3.00-4.00 sec 42.4 MBytes 356 Mbits/sec 30691
[ 5] 4.00-5.00 sec 42.5 MBytes 357 Mbits/sec 30782
[ 5] 5.00-6.00 sec 42.9 MBytes 360 Mbits/sec 31052
[ 5] 6.00-7.00 sec 42.9 MBytes 360 Mbits/sec 31049
[ 5] 7.00-8.00 sec 42.9 MBytes 360 Mbits/sec 31046
[ 5] 8.00-9.00 sec 42.9 MBytes 359 Mbits/sec 31034
[ 5] 9.00-10.00 sec 42.9 MBytes 360 Mbits/sec 31042
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-10.00 sec 427 MBytes 358 Mbits/sec 0.000 ms 0/309048 (0%) sender
[ 5] 0.00-10.05 sec 158 MBytes 132 Mbits/sec 0.036 ms 194168/308873 (63%) receiver

iperf Done.

Server:

-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 10.88.11.11, port 50210
[ 5] local 10.88.22.22 port 5201 connected to 10.88.11.11 port 55031
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-1.00 sec 14.8 MBytes 124 Mbits/sec 0.051 ms 18419/29132 (63%)
[ 5] 1.00-2.00 sec 16.3 MBytes 136 Mbits/sec 0.046 ms 19008/30790 (62%)
[ 5] 2.00-3.00 sec 16.1 MBytes 135 Mbits/sec 0.044 ms 19152/30782 (62%)
[ 5] 3.00-4.00 sec 16.0 MBytes 135 Mbits/sec 0.048 ms 19070/30683 (62%)
[ 5] 4.00-5.00 sec 15.9 MBytes 133 Mbits/sec 0.048 ms 19260/30762 (63%)
[ 5] 5.00-6.00 sec 15.8 MBytes 132 Mbits/sec 0.042 ms 19629/31054 (63%)
[ 5] 6.00-7.00 sec 15.8 MBytes 132 Mbits/sec 0.052 ms 19636/31045 (63%)
[ 5] 7.00-8.00 sec 15.5 MBytes 130 Mbits/sec 0.052 ms 19812/31039 (64%)
[ 5] 8.00-9.00 sec 15.6 MBytes 130 Mbits/sec 0.037 ms 19775/31040 (64%)
[ 5] 9.00-10.00 sec 16.0 MBytes 134 Mbits/sec 0.059 ms 19465/31049 (63%)
[ 5] 10.00-10.05 sec 785 KBytes 133 Mbits/sec 0.036 ms 942/1497 (63%)
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Jitter Lost/Total Datagrams
[ 5] 0.00-10.05 sec 158 MBytes 132 Mbits/sec 0.036 ms 194168/308873 (63%) receiver
iperf3: the client has unexpectedly closed the connection
-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------

As you can see, the packet loss is very high. Has anyone experience similar issue or know the root cause?

[jontsmith]

There is a performance improvement if you turn ON ethernet flow control (pause frames) in your switch.  Then the imx6 will pause the flow as the UDP buffer fills up.  I have seen the imx6 receive at 30 mbit/s with zero dropped packets with flow control on.  Without flow control, even 8 mbit/s is too fast and it drops some packets. 

You should be able to run this command and get zero loss.

iperf3 -u -c 10.88.22.22 -b 30M

[sonpham]

Hi igorpadykov,

what would you recommend for us to evaluate UDP link then?

[igorpadykov]

Hi Son

please check below reports, in particular measurements dependancy of iperf version:

Extremely high packet loss with UDP test · Issue #296 · esnet/iperf · GitHub 

Best regards
igor
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