In NSX for EDP, logical cores can be assigned automatically for packet processing in two methods. Each method has advantages depending on the nature of the traffic and workload configuration.
NSX supports automatic assignment of logical cores to vNICs such that dedicated logical cores manage the traffic to and from vNICs.
Every vNIC on a node has two directions for network traffic: one for incoming traffic (RX) and another for outgoing traffic (TX). Depending on the node configuration, each direction can also have multiple queues. A logical core can be assigned independently to a vNIC direction. When multiple logical cores are configured, the host automatically determines which logical core must be assigned to a vNIC direction.
The lcores are assigned based on the following configuration modes:
vNIC-count mode: In this default mode, the processing of incoming or outgoing traffic for any vNIC direction on an EDP switch requires the same amount of the CPU resources. Each logical core is assigned the same number of vNIC directions based on the available number of logical cores. This mode is reliable and must be used in cases where the traffic is symmetrical.
CPU-usage mode: In this mode, host continuously monitors the CPU usage required to process incoming or outgoing traffic at each vNIC direction on an EDP switch. Consider this mode in cases where the workload processes asymmetrical traffic distributions. In this mode, the host predicts where more resources are needed and changes the logical core assignments to balance the load among logical cores. The CPU usage mode is dynamic and helps achieve an optimal logical core assignment.
However, if the traffic pattern changes frequently, the predicted CPU resources requirement and the logical core assignment might also change frequently. Frequent changes to the logical core assignment can cause minimal packet drops.
In the vNIC-count mode, configure an appropriate number of logical cores. The number of logical cores to assign per NUMA, depends on the number of vNICs, the speed of the pNIC, the capabilities of the data plane workload, and the call model. The number of logical cores must be proportional to the number of vNICs so that each logical core can be assigned to a vNIC direction.
When a vNIC is connected or disconnected or when a logical core is added or removed, hosts automatically detect the changes and rebalance the logical core assignment. For information about setting the automatic logical core assignment mode, see the NSX Administration Guide.
