Currently the driver supports 16 queues per port.total of 32.
You can try enable RPS which is a standard interface for any NIC and set rps_cpus mask to the remaining 8 cores.
This will allow utilization of all the cores in the system.
Thank you for the information.
We tried RPS, but our testing showed it comes with a significant penalty compared to (hardware) RSS due to the extra required inter-processor interrupts. This is especially noticeable at high packet rates.