User Manual

Rev 2.3-1.0.1

Mellanox Technologies

Querying the Hardware Time

Querying the hardware for time is done via the

ibv_exp_query_values verb.

For example:

ret = ibv_exp_query_values(context, IBV_EXP_VALUES_HW_CLOCK, &queried_values);

if (!ret && queried_values.comp_mask & IBV_EXP_VALUES_HW_CLOCK)

queried_time = queried_values.hwclock;

To change the queried time in nanoseconds resolution, use the IBV_

EXP_

VALUES_HW_CLOCK_NS

flag along with the hwclock_ns field.

ret = ibv_exp_query_values(context, IBV_EXP_VALUES_HW_CLOCK_NS, &queried_values);

if (!ret && queried_values.comp_mask & IBV_EXP_VALUES_HW_CLOCK_NS)

queried_time_ns = queried_values.hwclock_ns;

Querying the Hardware Time is available only on physical functions / native machines.

3.1.11 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_exp_flow_attr), defined by a combination of

specifications (

struct ibv_exp_flow_spec_*).

3.1.11.1 Enable/Disable Flow Steering

Flow steering is generally enabled when the

log_num_mgm_entry_size module parameter is non

positive (e.g.,

-log_num_mgm_entry_size), meaning the absolute value of the parameter, is a bit

field. Every bit indicates a condition or an option regarding the flow steering mechanism:

bit Operation Description

b0 Force device managed Flow

Steering

When set to 1, it forces HCA to be enabled regardless of

whether NC-SI Flow Steering is supported or not.