User Manual

Driver FeaturesRev 2.2-1.0.1

Mellanox Technologies

4. The UP is mapped to the TC as configured by the mlnx_qos tool or by the lldpad daemon if

DCBX is used.

With RoCE, there can only be 4 predefined ToS values for the purpose of QoS mapping.

4.6.5 Raw Ethernet QP Quality of Service Mapping

Applications open a Raw Ethernet QP using VERBs directly.

The following is the RoCE QoS mapping flow:

1. The application sets the UP of the Raw Ethernet QP during the INIT to RTR state transition of

the QP:

• Sets

qp_attrs.ah_attrs.sl = up

• Calls modify_qp with IB_QP_AV set in the mask

2. The UP is mapped to the TC as configured by the

mlnx_qos tool or by the lldpad daemon if

DCBX is used

When using Raw Ethernet QP mapping, the TOS/sk_prio to UP mapping is lost.

Performing the Raw Ethernet QP mapping forces the QP to transmit using the given UP.

If packets with VLAN tag are transmitted, UP in the VLAN tag will be overwritten with

the given UP.

4.6.6 Map Priorities with tc_wrap.py/mlnx_qos

Network flow that can be managed by QoS attributes is described by a User Priority (UP). A

user's

sk_prio is mapped to UP which in turn is mapped into TC.

• Indicating the UP

• When the user uses

sk_prio, it is mapped into a UP by the ‘tc’ tool. This is done by the

tc_wrap.py tool which gets a list of <= 16 comma separated UP and maps the sk_prio to

the specified UP.

For example,

tc_wrap.py -ieth0 -u 1,5 maps sk_prio 0 of eth0 device to UP 1 and

sk_prio 1 to UP 5.

• Setting

set_egress_map in VLAN, maps the skb_priority of the VLAN to a vlan_qos.

The

vlan_qos is represents a UP for the VLAN device.

• In RoCE,

rdma_set_option with RDMA_OPTION_ID_TOS could be used to set the UP

• When creating QPs, the

sl field in ibv_modify_qp command represents the UP

• Indicating the TC

• After mapping the

skb_priority to UP, one should map the UP into a TC. This assigns

the user priority to a specific hardware traffic class. In order to do that,

mlnx_qos should