Profiling Jolt

Execution profiling

Jolt is instrumented using tokio-rs/tracing for execution profiling. We use the tracing_chrome crate to output traces in the format expected by Perfetto.

To generate a trace, run e.g.

cargo run --release -p jolt-core profile --name sha3 --format chrome

Where --name can be sha2, sha3, sha2-chain, fibonacci, or btreemap. The corresponding guest programs can be found in the examples directory. The benchmark inputs are provided in bench.rs.

The above command will output a JSON file in the workspace rootwith a name trace-<timestamp>.json, which can be viewed in Perfetto:

Memory profiling

Jolt uses allocative for memory profiling. Allocative allows you to (recursively) measure the total heap space occupied by any data structure implementing the Allocative trait, and optionally generate a flamegraph. In Jolt, most sumcheck data structures implement the Allocative trait, and we generate a flamegraph at the start and end of stages 2-5 of the Jolt DAG (see jolt_dag.rs).

To generate allocative output, run:

RUST_LOG=debug cargo run --release --features allocative -p jolt-core profile --name sha3 --format chrome

Where, as above, --name can be sha2, sha3, sha2-chain, fibonacci, or btreemap.

The above command will log memory usage info to the command line and output multiple SVG files, e.g. stage3_start_flamechart.svg, which can be viewed in a web browser of your choosing: