Layer 2 ef_vi Latency

Onload User Guide (UG1586)

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1.2 English

ef_vi is a network layer 2 API.

ef_vi test applications can be found in:


Run the eflatency UDP test application on both systems:

[sys-1]# taskset -c 1 eflatency <mode> -s <payload> pong <interface>
[sys-2]# taskset -c 1 eflatency <mode> -s <payload> ping <interface>


  • <mode> is -p only for 25 Gb, to force store and forward (no-poison) CTPIO
  • <payload> is the payload size, in bytes
  • <interface> is the interface to use.

The output gives various diagnostic information (ef_vi version, payload and frame length, number of iterations and warmups, and mode). It also identifies mean RTT, which is halved to give the mean ½ RTT latency.

Note: eflatency describes the eflatency application, command line options and provides example command lines.