Quartus® Prime Pro Edition User Guide: Design Constraints

ID 683143
Date 11/07/2024
Public
Document Table of Contents

2.1.3.2. Reporting NoC Performance

For designs that include the Hard Memory NoC, you can interactively generate a NoC Performance Report in Interface Planner.

The NoC Performance Report generation performs a static analysis of the NoC initiator and target locations to evaluate whether the placement allows your design to meet the bandwidth requirements and transaction sizes that you specify in the NoC Assignment Editor. You can review the report, and then make changes in the Plan tab based on the results.

To access the NoC Performance Report in Interface Planner, click the Reports tab, and then double-click Report NoC Performance in the Tasks pane.

Figure 27. Sample NoC Performance Report


The NoC Performance Report reports performance data for each initiator to target connection. The latencies in this report are based on the minimum structural latency with respect to the initiator and target placement. These latencies are for the NoC portion of the path only. These latencies do not include any latency of, for instance, external memory access. Nor do these latencies account for potential delay due to congestion on the NoC. You can achieve lower minimum structural latency by placing the NoC initiators and targets closer together.

The NoC Performance Report reports performance data for each initiator to target connection. You can achieve lower minimum structural latency by placing the NoC initiators and targets closer together. You can also display the congestion on the horizontal links visually in the NoC View.

To display this congestion after generating the report:

  1. Switch back to the Plan tab.
  2. Select the NoC View option.
  3. In the NoC View, right-click and enable Show NoC Congestion from the context menu.

    Any segments of the horizontal links that are congested are highlighted in red.

Table 12.  NoC Performance Report Data
NoC Performance Report Column Description
Requested RD BW The requested read bandwidth in GB per second. This value is the same as the value that you specify in the NoC Assignment Editor.
Requested WR BW The requested write bandwidth in GB per second. This value is the same as the value that you specify in the NoC Assignment Editor.
Initiator placement The placement location of the initiator element.
Target placement The placement location of the target element.
Message A message indicating whether you can achieve the requested bandwidth, or whether the connection is congested; and information about the cause of the congestion. The cause of congestion is an indication of where the congestion occurs, and which other connections contribute to that congestion.

One possible reason the Message reports that the current placement cannot meet the requested bandwidth is because of over-saturation of an initiator or a target. For example, if the sum of all bandwidth requirements through a particular initiator is greater than the bandwidth that the initiator can support, based on the data width and operating frequency of its AXI4 interface. To avoid this problem, either reduce bandwidth requirements or increase bandwidth capability.

Another possible reason that the current placement cannot meet the requested bandwidth is over-saturation of the horizontal bandwidth available in the NoC. This condition is the result of multiple initiator to target connections requesting bandwidth in the same direction through a horizontal section of the NoC. The NoC Performance Report message reports the congested segments. You can adjust initiator placement to alleviate congestion.

Note: For important considerations when choosing initiator interface placement, refer to the tables in Horizontal Bandwidth Considerations, along with tables in High-Speed Interconnect NoC Locations in Interface Planner in the Agilex® 7 M-Series FPGA Network-on-Chip (NoC) User Guide to translate location choices into physical placements.

You can also view NoC elements in the Quartus® Prime Chip Planner, and view connectivity of NoC elements in following fitting in the NoC Connectivity Report, as the Agilex® 7 M-Series FPGA Network-on-Chip (NoC) User Guide.