Hi there,

I'm developing a custom virtual switch 
using OVS-DPDK(v19.11.10). In order to achieve 10Gbit/s, I modified the OVS 
pmd mode from run-to-completion to pipeline. I used 1 thread as rx thread, 
4 threads as worker thread and 1 thread as tx thread.  it's a load balance 
archiecture.

I found the forwarding rate can reach 10Gbit/s in first 2 minite, and then drop to 5Gbit/s . My traffic generator keeps send packets at 10G rate. I debugged and found that packet loss occurred in `rte_eth_tx_burst`, then it invoke `ixgbe_xmit_pkts_vec` -> `ixgbe_xmit_fixed_burst_vec` , in `ixgbe_xmit_fixed_burst_vec`it should be `txq->nb_tx_free` < `nb_pkts`, it means there is not enough TX descriptor to be allocated.

I have tried increasing socket-mem when starting program and reducing the size of batch sent, neither worked. I wonder if i am missing something important? This question has been bugging me for weeks.

Does anyone know this issue?

Thanks,

BR,

Yalou