Entropyk/docs/benchmarks/phase-0-baseline.md

Phase-0 Performance Baseline

This document records the Phase-0 benchmark results for entropyk-solver. All later Epic-1 speedup claims (NFR1 ≥2× speedup, NFR2 100% parity) are measured against these numbers.

Environment

Property	Value
Date	2026-07-18
Host OS	Windows (x86_64)
Rust toolchain	1.89.0 (stable, pinned via rust-toolchain.toml)
Cargo profile	bench (release)
Linear algebra path	nalgebra 0.33 dense LU

How to Reproduce

# Ensure the pinned toolchain is active
cargo --version  # should report 1.89.0

# Run the full benchmark suite
cargo bench -p entropyk-solver

Benchmark Results

Results were produced by cargo bench -p entropyk-solver on the commit captured in the story frontmatter (baseline_commit).

LU Solve (Dense)

Benchmark	Mean time
lu_solve_mock_9x9	425.54 ns

Measures one Ruiz-equilibrated dense LU solve on the 9×9 Jacobian assembled from the deterministic mock refrigeration cycle.

Residual / Jacobian Assembly

Benchmark	Mean time
residual_assembly_mock	420.95 ns
jacobian_assembly_mock	157.47 ns

Measures a single full-system pass of compute_residuals and jacobian_entries on the mock cycle.

Full Solve — Reference Cycles

Each benchmark builds a real CoolProp-backed emergent-pressure R134a cycle (4 components, 9 unknowns) and solves it end-to-end with the fallback Newton solver.

Benchmark	Mean time
full_solve_reference_cycle_a	48.64 ms
full_solve_reference_cycle_b	67.06 ms
full_solve_reference_cycle_c	66.78 ms

Sequential Batch Solve Scaling

N	Mean time
1	56.03 ms
2	118.01 ms
4	240.03 ms

This is the Phase-0 sequential baseline. Parallel batch solving is out of scope and belongs to Epic 4.

Golden Snapshots

The golden regression test solves the three reference cycles and compares the converged state against committed canonical JSON snapshots. Run with ENTROPYK_BLESS=1 to regenerate snapshots after an intentional change.

Cycle	SHA-256 (canonical JSON)
golden_cycle_a.json	073408dede4ad4622272e9c9375d9f4823e7984ec9e54910a9790229d52af899
golden_cycle_b.json	c01e7cb892ed5829926c38ad5ee1423fdfaa7d262c473a8eca46ebc4632b9142
golden_cycle_c.json	6e1a77958cce1d1cf5e730505912a887c8bf4fc7dcaed820c7da482aa0ad9f98

Integration Corpus

The NFR2 parity corpus consists of 31 pre-existing integration test files in crates/solver/tests/ (including _scratch_debug.rs and _tmp_analytic.rs). This story added one new file (golden_snapshot.rs), bringing the solver test count to 32. The 31 pre-existing files must continue to pass unmodified as later Epic-1 stories land; golden_snapshot.rs is part of the Phase-0 safety net and must also remain green.

Reproduction Commands

# Ensure the pinned toolchain is active
cargo --version  # should report 1.89.0

# Full workspace test suite
cargo test --workspace

# Solver integration corpus only (includes golden snapshot)
cargo test -p entropyk-solver --tests

# Golden snapshot regression test specifically
cargo test -p entropyk-solver --test golden_snapshot --features coolprop

# Regenerate snapshots after an intentional physics/solver change
ENTROPYK_BLESS=1 cargo test -p entropyk-solver --test golden_snapshot --features coolprop

# Benchmark suite
cargo bench -p entropyk-solver

# Lint/format gates
cargo fmt --check
cargo clippy --workspace --all-targets -- -D warnings