Users Guide

7–RoCE Configuration
Configuring DCQCN
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Enabling DCQCN
To enable DCQCN for RoCE traffic, probe the qed driver with the dcqcn_enable
module parameter. DCQCN requires enabled ECN indications (see “Setting ECN
on RDMA Traffic” on page 173).
Configuring CNP
Congestion notification packets (CNPs) can have a separate configuration of
vLAN priority and DSCP. Control these packets using the dcqcn_cnp_dscp
and dcqcn_cnp_vlan_priority module parameters. For example:
modprobe qed dcqcn_cnp_dscp=10 dcqcn_cnp_vlan_priority=6
DCQCN Algorithm Parameters
Table 7-5 lists the algorithm parameters for DCQCN.
Table 7-5. DCQCN Algorithm Parameters
Parameter Description and Values
dcqcn_cnp_send_timeout Minimal difference of send time between CNPs.
Units are in microseconds. Values range between
50..500000.
dcqcn_cnp_dscp DSCP value to be used on CNPs. Values range
between 0..63.
dcqcn_cnp_vlan_priority vLAN priority to be used on CNPs. Values range
between 0..7. FCoE-Offload uses 3 and
iSCSI-Offload-TLV generally uses 4. Marvell rec-
ommends that you specify a number from 1–2 or
5–7. Use this same value throughout the entire net-
work.
dcqcn_notification_point 0 – Disable DCQCN notification point.
1 – Enable DCQCN notification point.
dcqcn_reaction_point 0 – Disable DCQCN reaction point.
1 – Enable DCQCN reaction point.
dcqcn_rl_bc_rate Byte counter limit
dcqcn_rl_max_rate Maximum rate in Mbps
dcqcn_rl_r_ai Active increase rate in Mbps
dcqcn_rl_r_hai Hyperactive increase rate in Mbps.
dcqcn_gd Alpha update gain denominator. Set to 32 for 1/32,
and so on.