User Manual

Rev 2.1-1.0.6
Mellanox Technologies
167
8.6 Quality of Service Management in OpenSM
8.6.1 Overview
When Quality of Service (QoS) in OpenSM is enabled (using the ‘-Q’ or ‘--qos’ flags), OpenSM
looks for a QoS Policy file. During fabric initialization and at every heavy sweep, OpenSM
parses the QoS policy file, applies its settings to the discovered fabric elements, and enforces the
provided policy on client requests. The overall flow for such requests is as follows:
• The request is matched against the defined matching rules such that the QoS Level def-
inition is found
• Given the QoS Level, a path(s) search is performed with the given restrictions imposed
by that level
Figure 4: QoS Manager
There are two ways to define QoS policy:
• Advanced – the advanced policy file syntax provides the administrator various ways to
match a PathRecord/MultiPathRecord (PR/MPR) request, and to enforce various QoS
constraints on the requested PR/MPR
• Simple – the simple policy file syntax enables the administrator to match PR/MPR
requests by various ULPs and applications running on top of these ULPs
8.6.2 Advanced QoS Policy File
The QoS policy file has the following sections:
I) Port Groups (denoted by port-groups)
This section defines zero or more port groups that can be referred later by matching rules (see
below). Port group lists ports by:
• Port GUID
• Port name, which is a combination of NodeDescription and IB port number
• PKey, which means that all the ports in the subnet that belong to partition with a given
PKey belong to this port group