Improve throughput of packets flowing from a vNIC to hypervisor or packets flowing in the reverse direction, by configuring multiple logical cores or Multiple Context functionality for vNIC queues.
In the Enhanced Datapath mode, you can configure Multiple Context functionality for vNIC traffic flowing to and from the hypervisor. Multiple Context means that multiple logical cores can serve Tx and Rx queues, in contrast to the single context, where one logical core serves both Tx and Rx queue. A Tx and Rx queue pair represents a vNIC queue.
As an admin, you might want to assign Multiple Context to vNIC queues based on the current network traffic or anticipated network traffic load. As traffic load increases for a vNIC queue, the configured single context or logical core for a specific vNIC queue might prove to be insufficient to load balance traffic. Assigning Multiple Context to that vNIC allocates more vCPU resources to load balance traffic.
The number of logical cores assigned depends on the capacity of the host.
The number of DRSS configurable on hosts depends on the maximum number of physical CPUs available on the host.
Logical cores can be shared across Default Receive Side Scaling (DRSS) and Multiple Context queues.
Both DRSS and Multiple Context can function independently. However, configuring them together provides additional performance benefits to physical hardware queues (DRSS) and vNIC queues. See Configure Default Queue Receive Side Scaling for more details on configuring DRSS.
- To configure the Multiple Context functionality for a vNIC, ensure that multiple logical cores are created on the host .
- Ensure that the host transport nodes are prepared in ENS Interrupt or Enhanced Datapath mode. The Multiple Context functionality is not available in the Standard mode.
- To verify that a host transport node is enabled for Enhanced Datapath:
- Navigate to .
- Select the transport node.
- Select the Overview tab and verify Enhanced Datapath Capable parameter is set to Yes.
- To configure Multiple Context functionality for vNIC traffic managed through Enhanced Datapath mode, edit configuration options of VMs and set the following parameter value. See the latest vSphere Virtual Machine Administration guide for details on how to edit VM configuration options.
ethernetX.ctxPerDev = "3"
Where, the value
3indicates that Multiple Context functionality is applied per vNIC queue.Other supported values for contexts are:
ethernetX.ctxPerDev =1indicates that Multiple Context functionality is applied per VM.
ethernetX.ctxPerDev =2indicates that Multiple Context functionality is applied per vNIC.