pmd_buffer_scatter Test Suite

Multi-segment packet scattering testing suite.

This testing suite tests the support of transmitting and receiving scattered packets. This is shown by the Poll Mode Driver being able to forward scattered multi-segment packets composed of multiple non-contiguous memory buffers. To ensure the receipt of scattered packets, the DMA rings of the port’s Rx queues must be configured with mbuf data buffers whose size is less than the maximum length.

If it is the case that the Poll Mode Driver can forward scattered packets which it receives, then this suffices to show the Poll Mode Driver is capable of both receiving and transmitting scattered packets.

class TestPmdBufferScatter

Bases: TestSuite

DPDK PMD packet scattering test suite.

Configure the Rx queues to have mbuf data buffers whose sizes are smaller than the maximum packet size. Specifically, set mbuf data buffers to have a size of 2048 to fit a full 1512-byte (CRC included) ethernet frame in a mono-segment packet. The testing of scattered packets is done by sending a packet whose length is greater than the size of the configured size of mbuf data buffers. There are a total of 5 packets sent within test cases which have lengths less than, equal to, and greater than the mbuf size. There are multiple packets sent with lengths greater than the mbuf size in order to test cases such as:

  1. A single byte of the CRC being in a second buffer while the remaining 3 bytes are stored in the first buffer alongside packet data.

  2. The entire CRC being stored in a second buffer while all of the packet data is stored in the first.

  3. Most of the packet data being stored in the first buffer and a single byte of packet data stored in a second buffer alongside the CRC.

set_up_suite() → None

Set up the test suite.

Setup:

Increase the MTU of both ports on the traffic generator to 9000 to support larger packet sizes.

scatter_pktgen_send_packet(pkt_size: int) → list[scapy.packet.Packet]

Generate and send a packet to the SUT then capture what is forwarded back.

Generate an IP packet of a specific length and send it to the SUT, then capture the resulting received packets and filter them down to the ones that have the correct layers. The desired length of the packet is met by packing its payload with the letter “X” in hexadecimal.

Parameters:

pkt_size (int) – Size of the packet to generate and send.

Returns:

The filtered down list of received packets.

Return type:

list[scapy.packet.Packet]

pmd_scatter(mb_size: int, enable_offload: bool = False) → None

Testpmd support of receiving and sending scattered multi-segment packets.

Support for scattered packets is shown by sending 5 packets of differing length where the length of the packet is calculated by taking mbuf-size + an offset. The offsets used in the test are -1, 0, 1, 4, 5 respectively.

Parameters:

  • mb_size (int) – Size to set memory buffers to when starting testpmd.

  • enable_offload (bool) – Whether or not to offload the scattering functionality in testpmd.

Test:

Start testpmd and run functional test with preset mb_size.

test_scatter_mbuf_2048() → None

Run the pmd_scatter() test with mb_size set to 2048.

test_scatter_mbuf_2048_with_offload() → None

Run the pmd_scatter() test with mb_size set to 2048 and rx_scatter offload.

tear_down_suite() → None

Tear down the test suite.

Teardown:

Set the MTU of the tg_node back to a more standard size of 1500.

required_capabilities: ClassVar[set[Capability]] = {NicCapability.RX_OFFLOAD_VLAN_STRIP}

The capabilities the test case or suite requires in order to be executed.