User Manual

Rev 2.3-1.0.1

Mellanox Technologies

Step 2. Enable ECN CLI.

options mlx4_ib en_ecn=1

Step 3. Restart the driver.

/etc/init.d/openibd restart

Step 4. Mount debugfs to access ECN attributes.

mount -t debugfs none /sys/kernel/debug/

Please note, mounting of debugfs is required.

The following is an example for ECN configuration through debugfs (echo 1 to enable attribute):

/sys/kernel/debug/mlx4_ib/<device>/ecn/<algo>/ports/1/params/prios/<prio>/<the

requested attribute>

ENC supports the following algorithms:

• r_roce_ecn_rp

• r_roce_ecn_np

Each algorithm has a set of relevant parameters and statistics, which are defined per device, per

port, per priority.

r_roce_ecn_np has an extra set of general parameters which are defined per device.

ECN and QCN are not compatible. When using ECN, QCN (and all its related dae-

mons/utilities that could enable it, i.e - lldpad) should be turned OFF.

3.1.7.2 Various ECN Paths

The following are the paths to ECM algorithm, general parameters and counters.

• The path to an algorithm attribute is (except for general parameters):

/sys/kernel/debug/mlx4_ib/{DEVICE}/ ecn/{algorithm}/ports/{port}/params/prios/{prio}/

{attribute}

• The path to a general parameter is:

/sys/kernel/debug/mlx4_ib/{DEVICE}/ ecn/r_roce_ecn_np/gen_params/{attribute}

• The path to a counter is:

/sys/kernel/debug/mlx4_ib/{DEVICE}/ ecn/{algorithm}/ports/{port}/statistics/prios/

{prio}/{counter}

3.1.8 Power Management

pm_qos API is used by mlx4_en, to enforce minimum DMA latency requirement on the system

when ingress traffic is detected. Additionally, it decreases packet loss on systems configured with

abundant power state profile when Flow Control is disabled.

The pm_qos API contains the following functions:

• pm_qos_add_request

• pm_qos_update_request

• pm_qos_remove_request