Profiling and tracing

VizTracer can record CPU traces and CPU and memory usage statistics for investigating HTTomo performance.

Record a serial run

$ python -m viztracer \
    --plugin "vizplugins --cpu_usage --memory_usage" \
    --output_file output.json \
    -m httomo run --no-standalone \
    data.nxs pipeline.yaml output_directory

Record an MPI run

Create a separate trace for each MPI rank:

$ mpirun -n 4 bash -c \
    'python -m viztracer \
    --plugin "vizplugins --cpu_usage --memory_usage" \
    --output_file output_rank_${OMPI_COMM_WORLD_RANK}.json \
    -m httomo run --no-standalone \
    data.nxs pipeline.yaml output_directory'

Combine and inspect traces

Combine the rank-specific traces:

$ viztracer --combine output_rank_*.json -o output.json

View the result locally:

$ vizviewer output.json

VizTracer output can also be opened using the online Perfetto viewer.