User Manual

Driver FeaturesRev 2.1-1.0.6

Mellanox Technologies

4.4.2 QoS Architecture

QoS functionality is split between the SM/SA, CMA and the various ULPs. We take the “chro-

nology approach” to describe how the overall system works.

1. The network manager (human) provides a set of rules (policy) that define how the network is

being configured and how its resources are split to different QoS-Levels. The policy also

define how to decide which QoS-Level each application or ULP or service use.

2. The SM analyzes the provided policy to see if it is realizable and performs the necessary fab-

ric setup. Part of this policy defines the default QoS-Level of each partition. The SA is

enhanced to match the requested Source, Destination, QoS-Class, Service-ID, PKey against

the policy, so clients (ULPs, programs) can obtain a policy enforced QoS. The SM may also

set up partitions with appropriate IPoIB broadcast group. This broadcast group carries its QoS

attributes: SL, MTU, RATE, and Packet Lifetime.

3. IPoIB is being setup. IPoIB uses the SL, MTU, RATE and Packet Lifetime available on the

multicast group which forms the broadcast group of this partition.

4. MPI which provides non IB based connection management should be configured to run using

hard coded SLs. It uses these SLs for every QP being opened.

5. ULPs that use CM interface (like SRP) have their own pre-assigned Service-ID and use it

while obtaining PathRecord/MultiPathRecord (PR/MPR) for establishing connections. The

SA receiving the PR/MPR matches it against the policy and returns the appropriate PR/MPR

including SL, MTU, RATE and Lifetime.

6. ULPs and programs (e.g. SDP) use CMA to establish RC connection provide the CMA the

target IP and port number. ULPs might also provide QoS-Class. The CMA then creates Ser

vice-ID for the ULP and passes this ID and optional QoS-Class in the PR/MPR request. The

resulting PR/MPR is used for configuring the connection QP.

PathRecord and MultiPathRecord Enhancement for QoS:

As mentioned above, the PathRecord and MultiPathRecord attributes are enhanced to carry the

Service-ID which is a 64bit value. A new field QoS-Class is also provided.

A new capability bit describes the SM QoS support in the SA class port info. This approach pro-

vides an easy migration path for existing access layer and ULPs by not introducing new set of

PR/MPR attributes.

4.4.3 Supported Policy

The QoS policy, which is specified in a stand-alone file, is divided into the following four sub-

sections:

I. Port Group

A set of CAs, Routers or Switches that share the same settings. A port group might be a partition

defined by the partition manager policy, list of GUIDs, or list of port names based on NodeDe-

scription.