libtrace might drop packets when filtering a NIC bound to DPDK

[Crazycuo]

Hi,

we are testing libtrace performance compared to dpdk and non-dpdk.

Here are our steps:

1. we use tcpreplay to replay a pcap in which all pakcets' src or dst port is 8119 on one computer(called A);
2. on another computer(called B), we write a c++ program which use libtrace to receive and filter "vlan and port 8119" pakcets. we print how many packets we received;
3. meanwhile, we use dpdk rte_eth_stats_get() to check if dpdk drop packets;
4. the two computers are directed connected. The two nics' name are p2p2;
5. we replay 83433 packets on computer A at the rate 100Mbps

so, on B computer, we test how many pakcets we recevie by bounding the p2p2 nic to dpdk or non-dpdk.
here are the result:
p2p2 on non-dpdk mode : receives 83433(no drop).
p2p2 on dpdk mode: only receives 80779. no matter how many times i re-test, i alway get 80779.

meanwhile, i use dpdk rte_eth_stats_get(), i got below:
Port 0 statistics:
RX packets: 383433
TX packets: 0
RX bytes: 32618600
TX bytes: 0
RX missed: 0
RX errors: 0
TX errors: 0
RX no buffer: 0

It looks like dpdk doesn't drop packets. (Rx missed and Rx no buffer is 0). so, it looks like libtrace is dropping pakcets?

Any ideas are appreciated!