You can collect profile statistics of your design by calling event APIs in your PS host code. These event APIs are available both during simulation and when you run the design in hardware.
The AI Engine has hardware performance counters and can be configured to count hardware events for measuring performance metrics. You can use the event API together with the graph control API to profile certain performance metrics during a controlled period of graph execution. The event API supports only platform I/O ports (PLIO & GMIO) to measure performance metrics such as platform I/O port bandwidth, graph throughput, and graph latency.
The event API tracks the events that occurred on the stream switch of the nets
that cross the AI Engine - PL interfaces.
The events on the stream switch of the nets include
stall, as shown in following figure.
- When there is no data passing the stream switch, the stream switch is in an
- When there is data passing the stream switch, the stream switch is in a
- When all the FIFOs on the net are full, the stream switch is in a
- When the transfer of data resumes, the stream switch returns to a
The following graph shows an example of data being sent from the
mm2s PL kernel to the AI Engine. It also shows the graph sending data
from the AI Engine to the
s2mm PL kernel.
Different ports can go through the same AI Engine - PL interface column, which shares the performance counters in the interface. You may check the array view in Vitis Analyzer to see which columns are those ports routing through. The following picture shows an array view of the above example, and note that the stream switches in red circle are where the event API is monitoring.
- The input buffer
buf0in the AI Engine is ready to accept data from the
mm2sPL kernel after the graph has been initialized. As soon as the
mm2sPL kernel starts, it will sequentially fill up the PING-PONG buffers and FIFOs inside the stream switch connected to the
buf0. The data transported to and from these buffers do not depend on
- Each column of the AI Engine -
PL interface has two performance counters. Because there are limited performance
event::stop_profiling()can be used to release the performance counters.
- There is some overhead when calling the graph and profiling APIs. The
profiling results can be read using the
event::read_profiling(). The profiling results can vary if the performance counters are not stopped before