Created attachment 287 [details]
mpps and packets stats of 8 cores 8 queues

Environment: Intel Cascadelak server running Centos 7.

Mellanox ConnectX6 NIC and used cores are on same one NUMA node.

Input traffic is always line rate 100Gbps, 64 bytes packets, 256 flows. 
Test duration is 30 seconds.

Run testpmd io mode with 7 cores and 7 queues: ./dpdk-testpmd -l 24-32 -n 4 -a
af:00.0 -- --nb-cores=7 --rxq=7 --txq=7 -i

Rx/Tx throughput is 91.6/91.6 MPPS. No TX-dropped packets. 

However, run testpmd io mode with 8 cores and 8 queues: ./dpdk-testpmd -l 24-32
-n 4 -a af:00.0 -- --nb-cores=8 --rxq=8 --txq=8 -i

Rx/Tx throughput is 113.6/85.4 MPPS. The tx is lower than tx of 7 core. There
are a lot of TX-dropped. Please refer to attached picture.

I notice similar issue on other x86 and aarch64 servers too.