Reproduce the Benchmark

The benchmark script lives in benchmark.ts at the repo root. It synthesizes a test workspace, runs each strategy, and measures rollback latency with process.hrtime.bigint().

Prerequisites

Node.js 20+
Git (for the legacy runner baseline)
Linux or WSL2 for tmpfs and rsync rows

Clone the repository:

git clone https://github.com/ayush585/Hyperion-Delta.git
cd Hyperion-Delta
npm ci

Smoke test

For a fast local regression check:

npm run benchmark:smoke

Smoke mode uses a small fixture and temporary work root. It validates the benchmark shape and strategy routing — not final performance evidence.

Full benchmark

For the full audit-scale defaults:

npm run benchmark

The full run preserves the audit-scale defaults in benchmark.ts. For the cleanest filesystem signal, run inside a native Linux filesystem or the XFS loopback mount used during audit testing. The tmpfs row appears automatically when /dev/shm is available.

Environment overrides

HYPERION_FILE_COUNT=1000 HYPERION_ITERATIONS=3 npm run benchmark

Variable	Default	Description
`HYPERION_FILE_COUNT`	50000	Number of files in the synthetic workspace
`HYPERION_ITERATIONS`	10	Rollback cycles per runner

WSL2 notes

When launched from WSL under /mnt/c, the script automatically stages generated benchmark workspaces in native Linux /tmp and prints the selected work root. This keeps the requested Windows project path usable while avoiding DrvFS metadata emulation from dominating the benchmark.

Interpreting results

The target outcome is not “copy-on-write always wins.” The meaningful result is:

Git reset scales with repository-wide filesystem inspection
Full tree clone/delete scales with repository-wide metadata churn
Hyperion targeted rollback scales with the dirty set
tmpfs dirty-set rollback shows the upper bound when rollback data stays in RAM

Strategy rows

Row	Requires	What it tests
Legacy Runner	Git	`git reset --hard` + `git clean -fd` baseline
Manifest Restore	None	Universal targeted rollback
rsync Link-Dest	`rsync`	POSIX copy-on-write optimization
tmpfs Dirty-Set	`/dev/shm`	RAM-backed rollback cache

If a required capability is unavailable, that row is reported as skipped instead of failing the run. The script prints the selected work root, fixture size, iteration count, and runner strategy rows before starting.