Performance Metrics - 2025.2 English - UG1076

Figure 1. Performance Metrics View

1. Click the Performance Metrics view.
2. Choose the stall type from the drop-down list. The metrics separate different types of stalls. It shows the existing stalls in the simulation result.

   Lock Stall Time (ps)

   The percentage of lock stall time during which buffers in the AI Engine tile are being acquired.

   Lock Stall Count

   The number of lock stalls in a specific tile.

   Memory Stall Time (ps)

   Percentage of memory stall time that memory accesses in the AI Engine tile have conflicts.

   Memory Stall Count

   The number of memory stalls in a specific tile.

   Stream Stall Time (ps)

   Percentage of stream stall time due to full or empty stream.

   Stream Stall Count

   The number of stream stalls in a specific tile.

   Cascade Stall Time (ps)

   Percentage of cascade stream stall time that either due cascade stream is full or empty.

   Cascade Stall Count

   The number of cascade stream stalls in a specific tile.

3. The Performance Metrics view shows each AI Engine tile as a bar. The higher the stall percentage, the more towards the right the bar is. Pay more attention to the highest bars. Click one of the bars to select the tile to focus.
4. The Tiles view at the bottom lists all the AI Engine tiles. It includes information about: column, row, kernels, buffers, all stall times, percentage, and count. Click the title row to sort on a specific column.
   Tip: When the number or information in the view is in green, the view can be cross-probed with other views.
5. Click the % button beside the drop-down list to switch between displaying the stall in percentage or absolute values.
6. While exploring the information in the Performance Metrics view, it is usually helpful to cross-probe with other views. For example, Trace View as shown below:
   Figure 2. Trace View
7. Choose the tile that has the largest stall time. Then go to the Trace view to see the position and frequency of the stalls.
8. Zoom in and out of the Trace view for a better view of the stall in the timeline.
9. Click on the Stalls view and from the drop-down list, select the type of stalls to examine. Select a stall in the Stalls view to highlight it in the Trace view.

The Performance Metrics view, Trace view, Graph view, and Array view can be cross-probed between each other. Graph view helps in understanding where the stall happens in the graph, and Array view helps in viewing the positions of the objects in hardware. The following sections explain more about analyzing each type of stall.