# ADR-0054: Milestone Eval Benches — self-contained sweep + figure benches

## Status

Accepted (2026-05-22).

Amends ADR-0044 (D1/D2) and ADR-0045 (D5) and supersedes the "logic lives
in `scripts/` + `tests/`" arrangement of ADR-0043/0044: the GEMM and
allreduce evaluation harnesses are now self-contained **benches** that a
user runs to regenerate every result + figure.

## Context

ADR-0043 (allreduce eval) and ADR-0044 (GEMM eval) split each harness into
a **sweep** (a manual `scripts/` driver, or — for allreduce — the
parametrized tests themselves) plus **figure tests** that render committed
data. The sweep/render logic therefore lived under `scripts/gemm_sweep.py`,
`tests/gemm/_gemm_plot_helpers.py`, and `tests/sccl/_allreduce_helpers.py`.

A milestone requirement ("refactor allreduce + GEMM evaluation so a user
can run *one bench* to generate all the results and plots") cannot be met
by that layout: a bench is production code and **must not import from
`tests/`** (ADR-0007 layer direction). The eval logic had to move into
production, reachable from a bench.

The chosen home is the bench module itself — not a separate
`kernbench.eval` package. A bench file may contain arbitrary module-level
code; collapsing the harness into the bench keeps one file per domain and
avoids an extra package layer.

## Decision

### D1. Two milestone benches own the eval logic

- `src/kernbench/benches/milestone_1h_gemm.py` — GEMM shape×variant sweep +
  the three figure renderers (moved from `scripts/gemm_sweep.py` +
  `tests/gemm/_gemm_plot_helpers.py`).
- `src/kernbench/benches/milestone_1h_ccl.py` — the distributed allreduce
  driver, latency + buffer-kind sweeps, topology diagram, FSIM comparison,
  and the direct-launch parity reference (moved from
  `tests/sccl/_allreduce_helpers.py`).

Each file is the **single home** for its domain's eval logic.

### D2. The "eval bench" pattern (extends ADR-0045 D5)

ADR-0045 D5 fixed a bench to a single configuration (single-SIP, or the
ADR-0024 multi-SIP CCL exception). This ADR adds a third pattern:

- An **eval bench** may drive *many* configurations and render figures. It
  builds its own per-config `GraphEngine` / `RuntimeContext` instances
  (one per sweep point) rather than using the outer `run_bench` engine.
- Because the outer ctx then has no submitted handles, the bench submits a
  **sentinel tensor** (`torch.zeros((1, 1), …)`) at the end to satisfy
  `run_bench`'s "must submit at least one request" contract (ADR-0045 D4),
  so the CLI exits 0.

### D3. Output location

Both benches write to `src/kernbench/benches/1H_milestone_output/{gemm,ccl}/`
(per user request — artifacts beside the bench). The directory holds only
generated PNG/CSV/JSON (never a `.py`/`__init__.py`), so the eager-import
audit (ADR-0045 first action) ignores it — `pkgutil.iter_modules` does not
yield non-package subdirectories. It is **git-ignored** (regenerable on
demand), unlike the committed `docs/diagrams/` artifacts.

### D4. GEMM heavy sweep — fresh by default, `MILESTONE_FAST` to reuse

`milestone-1h-gemm` runs the full 24-sim sweep by default (minutes; one
shape is 2048 tiles). `MILESTONE_FAST=1` reuses the committed
`docs/diagrams/gemm_sweep.json` and only re-renders (seconds). This
reverses ADR-0044 D1/D2's "heavy sweep stays a manual/`slow`-marked step":
running the bench *is* the regeneration. The slow path is exercised by a
`@pytest.mark.slow` bench test; the fast path runs by default.

### D5. Tests + script reuse via thin re-export shims (single home kept)

The pre-existing figure tests and the `scripts/gemm_sweep.py` entry point
are retained and now reuse the bench modules:

- `tests/gemm/_gemm_plot_helpers.py` → re-exports the renderers +
  `GEMM_SWEEP_JSON`/`GEMM_PLOTS_DIR`/`ROOT` from
  `kernbench.benches.milestone_1h_gemm`.
- `tests/sccl/_allreduce_helpers.py` → re-exports the driver core, config
  writers, sweep constants, renderers, and disk aggregators from
  `kernbench.benches.milestone_1h_ccl`, and keeps the **pytest-only** pieces
  local: the `pytest.param` matrices (`CONFIGS` / `_sweep_params` /
  `_bk_params`) and the fixture-coupled `_run_distributed`
  (`monkeypatch.chdir` + `_drive_distributed`) wrapper.
- `scripts/gemm_sweep.py` → thin wrapper over the bench's `run_sweep`.

Tests importing a bench module is permitted (tests sit above production,
ADR-0007); it triggers the whole-package eager audit, which already runs on
every `kernbench` invocation. matplotlib stays lazily imported inside the
renderers, so the audit's startup cost is unchanged.

### D6. Flat module naming (no `benches/` subfolder)

A `benches/` subpackage named `1H_milestone…` is impossible — a Python
package name cannot start with a digit. The benches are therefore flat
modules `milestone_1h_gemm.py` / `milestone_1h_ccl.py` with bench names
`milestone-1h-gemm` / `milestone-1h-ccl` (kebab-case, letter-first per
ADR-0045 D1).

## Consequences

### Positive

- `kernbench run --bench milestone-1h-gemm` (or `…-ccl`) regenerates all of
  a domain's results + figures in one command — the milestone requirement.
- Single source for the eval logic (the bench), reused by tests and the
  script via shims; no duplication.
- The figure tests and `scripts/gemm_sweep.py` keep working unchanged.

### Negative / limitations

- The two bench files are large (the CCL one mixes the distributed driver,
  sweeps, and matplotlib drawing). A "bench" that is mostly an eval harness
  is unusual; this ADR legitimizes it.
- Generated artifacts live inside the source tree (`src/kernbench/benches/`)
  by explicit request; git-ignored to avoid committing them.
- `milestone-1h-ccl` (and the default `milestone-1h-gemm`) take minutes —
  acceptable for an on-demand milestone artifact, not for routine runs.

## Dependencies

- **ADR-0007**: layer direction (why tests may import production but a bench
  may not import tests).
- **ADR-0043 / ADR-0044**: the allreduce / GEMM eval harnesses this ADR
  relocates into benches.
- **ADR-0045**: bench module contract; D2 here extends its D5 (single-device
  rule) with the eval-bench pattern, and relies on D4 (NO_REQUESTS) for the
  sentinel.
- **ADR-0024**: rank = SIP launcher driven by the allreduce sweeps.

## Open questions

- Should the GEMM theoretical-model constants (ADR-0044 D5) be sourced from
  ADR-0033/0014 rather than copied? Unchanged by this ADR.
- Should `build_overview_slides.py` consume the milestone output PNGs
  instead of drawing GEMM bars natively? Still open (ADR-0044 D6 / Negative).