Hi,

I'm running the copp test on my box and found out there is large gap of the value of RX counter between CPU and ptf_nn_agent:

I'm using /proc/bcm/knet/stats to get the RX counter of CPU like following after test(Ex, DHCPTest):

root@switch2:/home/admin# cat /proc/bcm/knet/stats | grep "Rx0 packets"
Rx0 packets 100127 --> About 100K packets received by CPU

But the RX counter of ptf_nn_agent is only around 83K

2017-10-20 01:27:45 : DHCPTest
2017-10-20 01:28:20 :
2017-10-20 01:28:20 : Counters before the test:
2017-10-20 01:28:20 : If counter (0, n): (87, 0)
2017-10-20 01:28:20 : NN counter (0, n): (66637, 500002)
2017-10-20 01:28:20 : If counter (1, n): (2, 0)
2017-10-20 01:28:20 : NN counter (1, n): (2, 0)
2017-10-20 01:28:20 :
2017-10-20 01:28:20 : Counters after the test:
2017-10-20 01:28:20 : If counter (0, n): (87, 100000)
2017-10-20 01:28:20 : NN counter (0, n): (66637, 600002)
2017-10-20 01:28:20 : If counter (1, n): (83074, 0)
2017-10-20 01:28:20 : NN counter (1, n): (83074, 0)
2017-10-20 01:28:20 :
2017-10-20 01:28:20 : Sent through NN to local ptf_nn_agent: 100000
2017-10-20 01:28:20 : Sent through If to remote ptf_nn_agent: 100000
2017-10-20 01:28:20 : Recv from If on remote ptf_nn_agent: 83072
2017-10-20 01:28:20 : Recv from NN on from remote ptf_nn_agent: 83072
2017-10-20 01:28:20 :
2017-10-20 01:28:20 : test stats
2017-10-20 01:28:20 : Packet sent = 100000
2017-10-20 01:28:20 : Packet rcvd = 83072
2017-10-20 01:28:20 : Test time = 0:00:23.654488
2017-10-20 01:28:20 : TX PPS = 4227
2017-10-20 01:28:20 : RX PPS = 3511
2017-10-20 01:28:20 :
2017-10-20 01:28:20 : Checking constraints (NoPolicy):
2017-10-20 01:28:20 : rx_pps (3511) > NO_POLICER_LIMIT (840): True
2017-10-20 01:28:20 : total_rcv_pkt_cnt (83072) > pkt_rx_limit (90000): False

After doing some research, I added 1µs delay between each send packet:

for i in xrange(count):
testutils.send_packet(self, send_intf, packet)
time.sleep(1.0 / 1000000.0)

Also I got pass result when I rerun test test when above script modification:

2017-10-20 01:45:19 : DHCPTest
2017-10-20 01:46:07 :
2017-10-20 01:46:07 : Counters before the test:
2017-10-20 01:46:07 : If counter (0, n): (11, 0)
2017-10-20 01:46:07 : NN counter (0, n): (66685, 1100002)
2017-10-20 01:46:07 : If counter (1, n): (23, 0)
2017-10-20 01:46:07 : NN counter (1, n): (567847, 0)
2017-10-20 01:46:07 :
2017-10-20 01:46:07 : Counters after the test:
2017-10-20 01:46:07 : If counter (0, n): (15, 100000)
2017-10-20 01:46:07 : NN counter (0, n): (66689, 1200002)
2017-10-20 01:46:07 : If counter (1, n): (98760, 0)
2017-10-20 01:46:07 : NN counter (1, n): (666584, 0)
2017-10-20 01:46:07 :
2017-10-20 01:46:07 : Sent through NN to local ptf_nn_agent: 100000
2017-10-20 01:46:07 : Sent through If to remote ptf_nn_agent: 100000
2017-10-20 01:46:07 : Recv from If on remote ptf_nn_agent: 98737
2017-10-20 01:46:07 : Recv from NN on from remote ptf_nn_agent: 98737
2017-10-20 01:46:07 :
2017-10-20 01:46:07 : test stats
2017-10-20 01:46:07 : Packet sent = 100000
2017-10-20 01:46:07 : Packet rcvd = 98733
2017-10-20 01:46:07 : Test time = 0:00:34.352164
2017-10-20 01:46:07 : TX PPS = 2911
2017-10-20 01:46:07 : RX PPS = 2874
2017-10-20 01:46:07 :
2017-10-20 01:46:07 : Checking constraints (NoPolicy):
2017-10-20 01:46:07 : rx_pps (2874) > NO_POLICER_LIMIT (840): True
2017-10-20 01:46:07 : total_rcv_pkt_cnt (98733) > pkt_rx_limit (90000): True

Please refer the following as my testbed topology:

[testbed_server]---[fan-out switch]---[DUT]
PTF_host_node remote_node
172.20.200.202 172.20.192.94

Using CLI "python ptf_nn_agent.py --device-socket 0@tcp://172.20.192.94:10900 -i 0-3@Ethernet12&" to bring up the remote node by ptf_nn_agent.py on DUT.

And run the copp test with CLI 'ansible-playbook test_sonic.yml -i inventory --limit DUT --become --tags copp --extra-vars "ptf_host=172.20.200.202"' on testbed server.

Not sure there is anyone hit the same or similar situation as mine. Also please advice me if any, thanks.

Regards,
Kenie Liu