High virtual network throughput performance tuning recommendation when using 100G network interface cards
Article ID: 312057
Updated On:
Products
Issue/Introduction
This article provides performance tuning recommendations for physical NICs in a vSphere environment.
Symptoms:
Users might not see a high enough throughput for a VNIC to fill the physical NIC bandwidth.
Environment
VMware NSX 4.0.0.1
VMware vSphere ESXi 8.0.2
Cause
By default, ESX/NSX networking uses limited number of threads to service Tx and Rx of a vNIC. Throughput of a vNIC is limited by the processing capacity of those threads.
Resolution
If a vNIC requires high throughput, whether just high Rx side throughput or bi-directional, is is recommended to configure ethernetX.pnicFeatures=4, and ethernetX.ctxPerDev=3 in the virtual machine's VMX file, to get the parallelism in the networking layer. This gives a much more balanced Tx side and Rx side bandwidth, roughly equally in the bi-directional test. These tunings work best with pNIC RSS enabled.
Relevant documents:
Receive Side Scaling
Performance Best Practices for VMware vSphere 8.0
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