User Manual

Driver FeaturesRev 2.1-1.0.6

Mellanox Technologies

• ibv_open_qp

Please use ibv_xsrq_pingpong for basic tests and code reference. For detailed information

regarding the various options for these verbs, please refer to their appropriate man pages.

4.12 Flow Steering

Flow Steering is applicable to the mlx4 driver only.

Flow steering is a new model which steers network flows based on flow specifications to specific

QPs. Those flows can be either unicast or multicast network flows. In order to maintain flexibil-

ity, domains and priorities are used. Flow steering uses a methodology of flow attribute, which is

a combination of L2-L4 flow specifications, a destination QP and a priority. Flow steering rules

may be inserted either by using ethtool or by using InfiniBand verbs. The verbs abstraction uses a

different terminology from the flow attribute (ibv_flow_attr), defined by a combination of speci-

fications (struct ibv_flow_spec_*).

4.12.1 Enable/Disable Flow Steering

Flow Steering is disabled by default and regular L2 steering is performed instead (B0 Steering).

When using SR-IOV, flow steering is enabled if there is an adequate amount of space to store the

flow steering table for the guest/master.

 To enable Flow Steering:

Step 1. Open the /etc/modprobe.d/mlnx.conf file.

Step 2. Set the parameter log_num_mgm_entry_size to -1 by writing the option mlx4_core

log_num_mgm_entry_size=-1

Step 3. Restart the driver

 To disable Flow Steering:

Step 1. Open the /etc/modprobe.d/mlnx.conf file.

Step 2. Remove the options mlx4_core log_num_mgm_entry_size= -1.

Step 3. Restart the driver

4.12.2 Flow Domains and Priorities

Flow steering defines the concept of domain and priority. Each domain represents a user agent

that can attach a flow. The domains are prioritized. A higher priority domain will always super-

sede a lower priority domain when their flow specifications overlap. Setting a lower priority

value will result in higher priority.

In addition to the domain, there is priority within each of the domains. Each domain can have at

most 2^12 priorities in accordance with its needs.

The following are the domains at a descending order of priority:

• User Verbs allows a user application QP to be attached into a specified flow when

using

ibv_create_flow and ibv_destroy_flow verbs