Add the ability to profile the benchmarks w/ a flamegraph feature (#183)

* feat: Integrate flamegraph profiling in benchmarks

- Introduce "flamegraph" feature flag for optional profiling integration
- Add benchmark profiling support in `compressed_snark` and `recursive_snark` groups
- Update Cargo.toml with `pprof` and `cfg-if` dependencies

* ci: Build benches to make sure they don't bit-rot

- Integrate bench build step into GitHub Actions workflow

.github/workflows/rust.yml

@@ -25,6 +25,8 @@ jobs:
       run: cargo build --target wasm32-unknown-unknown
     - name: Build examples
       run: cargo build --examples --verbose
+    - name: Build benches
+      run: cargo build --benches --verbose
     - name: Run tests
       run: cargo +stable test --release --verbose
     - name: Check Rustfmt Code Style

Cargo.toml

@@ -40,6 +40,8 @@ pasta-msm = { version = "0.1.4" }
 criterion = { version = "0.4", features = ["html_reports"] }
 rand = "0.8.4"
 hex = "0.4.3"
+pprof = { version = "0.11" }
+cfg-if = "1.0.0"
 
 [[bench]]
 name = "recursive-snark"
@@ -59,3 +61,4 @@ default = []
 portable = ["pasta-msm/portable"]
 cuda = ["neptune/cuda", "neptune/pasta", "neptune/arity24"]
 opencl = ["neptune/opencl", "neptune/pasta", "neptune/arity24"]
+flamegraph = ["pprof/flamegraph", "pprof/criterion"]

benches/compressed-snark.rs

@@ -22,10 +22,24 @@ type S2 = nova_snark::spartan::RelaxedR1CSSNARK;
 type C1 = NonTrivialTestCircuit<<G1 as Group>::Scalar>;
 type C2 = TrivialTestCircuit<<G2 as Group>::Scalar>;
 
-criterion_group! {
-name = compressed_snark;
-config = Criterion::default().warm_up_time(Duration::from_millis(3000));
-targets = bench_compressed_snark
+// To run these benchmarks, first download `criterion` with `cargo install cargo install cargo-criterion`.
+// Then `cargo criterion --bench compressed-snark`. The results are located in `target/criterion/data/<name-of-benchmark>`.
+// For flamegraphs, run `cargo criterion --bench compressed-snark --features flamegraph -- --profile-time <secs>`.
+// The results are located in `target/criterion/profile/<name-of-benchmark>`.
+cfg_if::cfg_if! {
+  if #[cfg(feature = "flamegraph")] {
+    criterion_group! {
+      name = compressed_snark;
+      config = Criterion::default().warm_up_time(Duration::from_millis(3000)).with_profiler(pprof::criterion::PProfProfiler::new(100, pprof::criterion::Output::Flamegraph(None)));
+      targets = bench_compressed_snark
+    }
+  } else {
+    criterion_group! {
+      name = compressed_snark;
+      config = Criterion::default().warm_up_time(Duration::from_millis(3000));
+      targets = bench_compressed_snark
+    }
+  }
 }
 
 criterion_main!(compressed_snark);

benches/recursive-snark.rs

@@ -18,10 +18,24 @@ type G2 = pasta_curves::vesta::Point;
 type C1 = NonTrivialTestCircuit<<G1 as Group>::Scalar>;
 type C2 = TrivialTestCircuit<<G2 as Group>::Scalar>;
 
-criterion_group! {
-name = recursive_snark;
-config = Criterion::default().warm_up_time(Duration::from_millis(3000));
-targets = bench_recursive_snark
+// To run these benchmarks, first download `criterion` with `cargo install cargo install cargo-criterion`.
+// Then `cargo criterion --bench recursive-snark`. The results are located in `target/criterion/data/<name-of-benchmark>`.
+// For flamegraphs, run `cargo criterion --bench recursive-snark --features flamegraph -- --profile-time <secs>`.
+// The results are located in `target/criterion/profile/<name-of-benchmark>`.
+cfg_if::cfg_if! {
+  if #[cfg(feature = "flamegraph")] {
+    criterion_group! {
+      name = recursive_snark;
+      config = Criterion::default().warm_up_time(Duration::from_millis(3000)).with_profiler(pprof::criterion::PProfProfiler::new(100, pprof::criterion::Output::Flamegraph(None)));
+      targets = bench_recursive_snark
+    }
+  } else {
+    criterion_group! {
+      name = recursive_snark;
+      config = Criterion::default().warm_up_time(Duration::from_millis(3000));
+      targets = bench_recursive_snark
+    }
+  }
 }
 
 criterion_main!(recursive_snark);