7–RoCE Configuration
Configuring DCQCN
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DCB-related Parameters
Use DCB to map priorities to traffic classes (priority groups). DCB also controls
which priority groups are subject to PFC (lossless traffic), and the related
bandwidth allocation (ETS).
Global Settings on RDMA Traffic
Global settings on RDMA traffic include configuration of vLAN priority, ECN, and
DSCP.
Setting vLAN Priority on RDMA Traffic
Use an application to set the vLAN priority used by a specified RDMA Queue Pair
(QP) when creating a QP. For example, the
ib_write_bw
benchmark controls
the priority using the
-sl
parameter. When RDMA-CM (RDMA Communication
Manager) is present, you may be unable to set the priority.
Another method to control the vLAN priority is to use the
rdma_glob_vlan_pri
node. This method affects QPs that are created after setting the value. For
example, to set the vLAN priority number to 5 for subsequently created QPs,
issue the following command:
./debugfs.sh -n eth0 -t rdma_glob_vlan_pri 5
Setting ECN on RDMA Traffic
Use the
rdma_glob_ecn
node to enable ECN for a specified RoCE priority. For
example, to enable ECN on RoCE traffic using priority 5, issue the following
command:
./debugfs.sh -n eth0 -t rdma_glob_ecn 1
This command is typically required when DCQCN is enabled.
Setting DSCP on RDMA Traffic
Use the
rdma_glob_dscp
node to control DSCP. For example, to set DSCP on
RoCE traffic using priority 5, issue the following command:
./debugfs.sh -n eth0 -t rdma_glob_dscp 6
This command is typically required when DCQCN is enabled.
Configuring DSCP-PFC
Use
dscp_pfc
nodes to configure the
dscp->priority
association for PFC.
You must enable the feature before you can add entries to the map. For example,
to map DSCP value 6 to priority 5, issue the following commands:
./debugfs.sh -n eth0 -t dscp_pfc_enable 1
./debugfs.sh -n eth0 -t dscp_pfc_set 6 5
