[ovs-dev] Question about port statistics

[Junguk Cho]

Hi,

I used userplane OVS-2.7 with DPDK-16.11.1.
I set up two dpdk ring device ports in OVS.

27afd0dc-cdac-4bb4-947c-65e13df66e99
    Bridge "br0"
        Controller "tcp:10.1.2.2"
            is_connected: true
        fail_mode: secure
        Port "dpdkr2"
            Interface "dpdkr2"
                type: dpdkr
        Port "dpdkr1"
            Interface "dpdkr1"
                type: dpdkr
        Port "br0"
            Interface "br0"
                type: internal

I send traffic from dpdkr2 to dpdkr1 (Traffic rate is about 30MB/s) .
However, sometimes I saw packets drops.
When I printed out port statistics at that time, I saw tx_dropped and
tx_errors.

{rx_bytes=0, rx_dropped=0, rx_errors=0, rx_packets=0, tx_bytes=0,
tx_dropped=7068, tx_errors=7906, tx_packets=9043283}
{rx_bytes=0, rx_dropped=0, rx_errors=0, rx_packets=9050351, tx_bytes=0,
tx_dropped=0, tx_errors=0, tx_packets=0}

It seemed tx_dropped + tx_packets are equal to rx_packets.
What tx_dropped and tx_errors mean? What are the reasons?
Also, if tx_dropped means dropping packets, how rx_packets are higher than
tx_packets?

Thanks.