Improving and increasing CPU utilization observed in some networking workloads for Mellanox (Cx-5) 100G NIC.

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

Increase in CPU utilization in some networking workloads (non-ENS).

Environment

VMware vSphere ESXi 8.0

Cause

nmlx5 driver increased default queue count to 24 to support higher throughput devices. While this helps to achieve pNic throughput improvements, it can also result in increased CPU utilization in some workloads.

Resolution

Load the driver with queue count to 16, to reduce the CPU utilization.

Workaround:

Load nmlx5 driver with below settings

esxcli system module parameters set -m nmlx5_core -p "max_queues=16 RSS=4 GEN_RSS=2"