Onload User Guide (UG1586)

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1.2 English

The ef_vi API is a layer 2 API that grants an application direct access to the Solarflare network adapter datapath to deliver lower latency and reduced per message processing overheads. ef_vi is the internal API used by Onload for sending and receiving packets. It can be used directly by applications that want the very lowest latency send and receive API and that do not require a POSIX socket interface.

  • ef_vi is packaged with the Onload distribution.
  • ef_vi is an OSI level 2 interface which sends and receives raw Ethernet frames.
  • ef_vi supports a zero-copy interface because the user process has direct access to memory buffers used by the hardware to receive and transmit data.
  • An application can use both ef_vi and Onload at the same time. For example, use ef_vi to receive UDP market data and Onload sockets for TCP connections for trading.
  • The ef_vi API can deliver lower latency than Onload and incurs reduced per message overheads.
  • ef_vi is free software distributed under a LGPL license.
  • The user application wishing to use the layer 2 ef_vi API must implement the higher layer protocols.