The Timeline Trace collects and displays host and kernel events on a common timeline to help you understand and visualize the overall health and performance of your systems. The graphical representation lets you see issues regarding kernel synchronization and efficient concurrent execution. The displayed events include:
- XRT API calls from the host code
- Device trace data including compute units, AXI transaction start/stop
- Host events and kernel start/stops
While the timeline and device trace data are useful for debugging and profiling the application, collecting the data can affect application performance by adding time to the execution. However, the trace data is collected with dedicated resources in the kernel, and so does not affect kernel functionality. By default, the collected trace data is offloaded at the end of the run, though the tool can be configured to offload data continuously which can help when debugging application crashes.
The following is a snapshot of the Timeline Trace window which displays host and device events on a common timeline. Host activity is displayed at the top of the image and kernel activity is shown on the bottom of the image. Host activities include creating the program, running the kernel and data transfers between global memory and the host. The kernel activities include read/write accesses and transfers between global memory and the kernel(s). This information helps you understand details of application execution and identify potential areas for improvements.
Timeline data can be enabled and collected through the command line flow. However, viewing must be done in the Vitis analyzer as described in Working with the Analysis View (Vitis Analyzer) in the Vitis Reference Guide (UG1702).