Intel® Ethernet 800 Series Linux Flow Control
Configuration Guide for RDMA Use Cases
Step 1: Determine Flow Control Design Needed
Ensure that the QoS design is defined for the application per port. You will need to know the following parameters:
- Number of TCs and which TCs will use PFC
- DSCP mode or VLAN PFC/PCP mode to be used for PFC
- Priorities for the TCs
- Bandwidth allocation for the TCs
- Application ToS values
- Common ToS values for VLAN PFC are 0, 8, 16, and 24. These correspond with priorities 0, 2, 6, and 4, respectively. See Step 2: Kernel Priority (sk_prio) or DSCP to UP Mapping for details.
- DSCP is the upper six bits of the 8-bit ToS field. For historical reasons, DSCP and ToS are often used somewhat interchangeably, but they are different. Applications tend to set the entire ToS field, as this document references.