HCCL_RDMA_TC

Description

Sets the traffic class of the RDMA NIC.

The value of this environment variable ranges from [0, 255] and must be an integral multiple of 4. The default value is 132.

In the RoCE V2 protocol, this value corresponds to the type of service (ToS) field in the IP packet header. The ToS field consists of 8 bits. Specifically, bits [0, 1] are fixed at 0, and bits [2, 7] indicate the DSCP value (calculated by dividing the environment variable value by 4).

Example

# If this environment variable is set to 100 (25 × 4), the DSCP value is 25.
export HCCL_RDMA_TC=100

Restrictions

If you call the HCCL C APIs to initialize a communicator with specific configurations and set the traffic class of the RDMA NIC using the hcclRdmaTrafficClass parameter of HcclCommConfig, the configuration of the communicator takes precedence.

Applicability

Atlas A3 training products / Atlas A3 inference products

Atlas A2 training products / Atlas A2 inference products (For Atlas A2 training products / Atlas A2 inference products , only the Atlas 800T A2 training server, Atlas 900 A2 PoD cluster basic unit, and Atlas 200T A2 Box16 heterogeneous subrack are supported.)

Atlas training products

Atlas inference products (For the Atlas inference products , only the Atlas 300I Duo inference card is supported.)