Profiling

Requires the profiling feature.

Syren can emit a timeline of where a tick spends its time as a Chrome Trace file, viewable in chrome://tracing or Perfetto.

Spans compile away when off

The framework and model code annotate work with tracing spans. When the profiling feature is off, those spans compile to nothing, so a build without the feature has no span overhead and span annotations can stay in model code.

Capturing a trace

Initialise the profiler with an output path before running, and shut it down afterwards so the trace is flushed:

syren::init("profile/run.json");
// ... run the model ...
syren::shutdown();

The framework's own systems and boundaries are already instrumented, so a capture shows the stages of each tick and the time inside them. Add spans in your systems to attribute time to specific model phases.

Reading a trace

Open the JSON file in chrome://tracing or Perfetto. Each tick appears as a run of stages, with the systems in a stage executing in parallel. A trace shows whether time is spent in one system, in a stage that parallelises poorly, or in structural mutation at a scheduler boundary.

See collect results and profiles and performance methodology.