How Onload Uses Packet Buffers

Each packet buffer is allocated to exactly one Onload stack and is used to receive, transmit or queue network data. Packet buffers are used by Onload in the following ways:

1. Receive descriptor rings. By default the RX descriptor ring will hold 512 packet buffers at all times. This value is configurable using the EF_RXQ_SIZE (per stack) variable.
2. Transmit descriptor rings. By default the TX descriptor ring will hold up to 512 packet buffers. This value is configurable using the EF_TXQ_SIZE (per stack) variable.
3. To queue data held in socket receive and send buffers.
4. TCP sockets can also hold packet buffers in the socket’s retransmit queue and in the reorder queue.
5. User-level pipes also consume packet buffer resources.