Achieve a high throughput for a VNIC for customers who use 100G NICs
Article ID: 312057
Updated On:
Products
Issue/Introduction
This article is a useful for performance tuning recommendation for users.
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, our recommendation is that the vNIC will need to configure ethernetX.pnicFeatures=4, and ethernetX.ctxPerDev=3 in 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:
1. https://docs.vmware.com/en/VMware-NSX/4.1/administration/GUID-4A1E3CE2-1362-4927-84CD-999F78BAA5F9.html
2. https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/whitepaper/vmware-vsphere-pnics-performance-white-paper.pdf
Workaround:
Currently there is no workaround.
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