Intel® Arria® 10 Hard Processor System Technical Reference Manual

ID 683711
Date 1/10/2023
Public

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8.1.6. About Arbitration and Quality of Service

When multiple transactions need the same interconnect resource at the same time, arbitration logic resolves the contention. The quality-of-service (QoS) logic gives you control over how the contention is resolved.

Arbitration and QoS logic work together to enable optimal performance in your system. For example, by setting QoS parameters, you can prevent one master from using up the interconnect's bandwidth at the expense of other masters.

The system interconnect supports QoS optimization through programmable QoS generators. The QoS generators are located on interconnect initiators, which correspond to master interfaces. The initiators insert packets into the interconnect, with each packet carrying a transaction between a master and a slave. Each QoS generator creates control signals that prioritize the handling of individual transactions to meet performance requirements.

Arbitration and QoS in the HPS system interconnect are based on the following concepts:

  • Priority—Each packet has a priority value. The arbitration logic generally gives resources to packets with higher priorities.
  • Urgency—Each master has an urgency value. When it initiates a packet, it assigns a priority equal to its urgency.
  • Pressure—Each data path has a pressure value. If the pressure is raised, packets on that path are treated as if their priority was also raised.
  • Hurry—Each master has a hurry value. If the hurry is raised, all packets from that master are treated as if their priority was also raised.

Proper QoS settings depend on your performance requirements for each component and peripheral, and for system performance as a whole. Intel recommends that you become familiar with QoS optimization techniques before you try to change the QoS settings in the HPS system interconnect.