uzu-quant-kit / scripts /preflight.py
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Rebuild: 45434a3a (bf16 guard on pre-Ampere)
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#!/usr/bin/env python3
"""Preflight a machine before a lane starts.
Two T4 lanes died 10 minutes in because Turing has no BF16 matmul and lalamo's
attention requests `ALG_DOT_BF16_BF16_F32`. Catch that in seconds instead.
python scripts/preflight.py
python scripts/preflight.py --strict # exit 1 when BF16 is unavailable
python scripts/preflight.py --json out.json
Checks: jax devices, compute capability, an actual BF16 matmul, working/RAM/disk,
and the kit manifest commit when present.
"""
from __future__ import annotations
import argparse
import json
import os
import re
import shutil
import subprocess
import sys
from pathlib import Path
TRITON_MIN = 8.0
def parse_capabilities(output: str) -> list[float]:
values = []
for line in output.splitlines():
text = line.strip().split(",")[0].strip()
try:
values.append(float(text))
except ValueError:
continue
return values
def verdict(capabilities: list[float], probes: dict | None = None) -> dict:
"""Pure decision table so it can be tested without a GPU."""
probes = probes or {}
ampere = bool(capabilities) and all(value >= TRITON_MIN for value in capabilities)
def status(name: str) -> str:
return str(probes.get(name, "skip"))
# qad_grad is checked separately: it needs a mesh context that non-QAD
# lanes never create, so a failure there must not block ordinary lanes.
core = ("dot", "dot_f32_acc", "sdpa_xla", "quant_roundtrip", "tokenizer")
failures = [name for name in core if status(name) == "fail"]
qad_failure = status("qad_grad") == "fail"
bf16 = all(status(name) == "pass" for name in ("dot", "dot_f32_acc", "sdpa_xla"))
if status("sdpa_xla") == "fail":
attention = "unavailable"
note = "dot_product_attention is unsupported on this GPU: use CPU or Modal"
elif status("sdpa_xla") == "pass":
attention = "default"
note = "" if bf16 else "BF16 accumulation unsupported: use float32"
else:
attention = "default" if ampere else "xla"
note = "" if bf16 else "BF16 unsupported: use float32 or CPU/Modal"
return {
"ampere_or_newer": ampere,
"bf16_matmul": bf16,
"bf16_source": "measured" if probes else "capability",
"probes": probes,
"probe_failures": failures,
"lane_ok": not failures,
"qad_ok": not qad_failure,
"eval_dtype": "bfloat16" if bf16 else "float32",
"attention": attention,
"note": note,
}
PROBES = {
# plain bf16 matmul: T4 passes this (XLA upcasts internally)
"dot": (
"import jax.numpy as jnp\n"
"x = jnp.ones((32, 32), dtype=jnp.bfloat16)\n"
"(x @ x).block_until_ready()\n"
),
# bf16 inputs with f32 accumulation. Shape matters: a 32x32 dot is lowered
# differently and passes on T4, which made the gate useless. Real shapes
# pick ALG_DOT_BF16_BF16_F32 and fail on pre-Ampere GPUs.
"dot_f32_acc": (
"import jax.numpy as jnp\n"
"x = jnp.ones((512, 1024), dtype=jnp.bfloat16)\n"
"jnp.dot(x, x.T, preferred_element_type=jnp.float32).block_until_ready()\n"
),
# lalamo's xla attention uses jax.nn.dot_product_attention(implementation='xla').
# Use production-ish shape (1, heads, tokens, head_dim); tiny probes pass on T4.
"sdpa_xla": (
"import jax, jax.numpy as jnp\n"
"q = jnp.ones((1, 12, 512, 64), dtype=jnp.bfloat16)\n"
"jax.nn.dot_product_attention(q, q, q, implementation='xla').block_until_ready()\n"
),
# tokenizer: load and round-trip both scripts
"tokenizer": (
"import sys\n"
"from tokenizers import Tokenizer\n"
"tok = Tokenizer.from_file(sys.argv[1])\n"
"for text in ('the quick brown fox', '日本語のテキストです'):\n"
" ids = tok.encode(text).ids\n"
" assert ids, text\n"
" tok.decode(ids)\n"
),
# quantize / dequantize a tiny matrix through lalamo's INT4 + RHT path
"quant_roundtrip": (
"from lalamo.compressed.hybrid import HybridSpec\n"
"from lalamo.compressed.int import IntSpec\n"
"from lalamo.compressed.incoherence import HadamardSpec, IncoherenceProcessingMode\n"
"from lalamo.utils.sharding import ShardingConfig\n"
"from lalamo.weight_matrix import Layout\n"
"import jax, jax.numpy as jnp, numpy as np\n"
"spec = HybridSpec(\n"
" quantization_spec=IntSpec(bits=4, group_size=32, is_symmetric=False, layout=Layout.OUTPUT_INPUT),\n"
" adapter_spec=None,\n"
" incoherence_spec=HadamardSpec(block_size=32, processing_mode=IncoherenceProcessingMode.INPUT_OUTPUT),\n"
")\n"
"cfg = ShardingConfig.replicated()\n"
"w = jax.device_put(np.random.RandomState(0).randn(64, 32).astype(np.float32), cfg.resolve_sharding((None, None)))\n"
"compressed = spec.compress(w, key=jax.random.key(0), sharding_config=cfg)\n"
"restored = compressed.decompress()\n"
"assert bool(jnp.isfinite(restored).all())\n"
"assert restored.shape == w.shape\n"
),
# QAD gradient path: finite grads through quantize/dequantize
"qad_grad": (
"from lalamo.compressed.hybrid import HybridSpec\n"
"from lalamo.compressed.int import IntSpec\n"
"from lalamo.utils.sharding import ShardingConfig\n"
"from lalamo.weight_matrix import Layout\n"
"import jax, jax.numpy as jnp, numpy as np\n"
"spec = HybridSpec(\n"
" quantization_spec=IntSpec(bits=4, group_size=32, is_symmetric=False, layout=Layout.OUTPUT_INPUT),\n"
" adapter_spec=None, incoherence_spec=None,\n"
")\n"
"sharding = ShardingConfig.replicated()\n"
"def loss(w):\n"
" return jnp.sum(spec.compress(w, key=jax.random.key(0), sharding_config=sharding).decompress() ** 2)\n"
"w = jax.device_put(np.random.RandomState(0).randn(64, 32).astype(np.float32), sharding.resolve_sharding((None, None)))\n"
"mesh = sharding.resolve_sharding((None, None)).mesh\n"
"with jax.set_mesh(mesh):\n"
" grad = jax.grad(loss)(w)\n"
"assert bool(jnp.isfinite(grad).all())\n"
),
}
# probes that need lalamo; missing lalamo is a skip, not a failure
LALAMO_PROBES = {"quant_roundtrip", "qad_grad"}
def classify_probe_failure(name: str, message: str) -> tuple[str, str | None]:
"""Missing top-level lalamo is a skip; a missing submodule is a failure.
The PyPI lalamo 0.17.0 tree reports ModuleNotFoundError for
``lalamo.compressed.incoherence``. Treating that as "skip" would let the
wrong environment pass the gate.
"""
if name in LALAMO_PROBES and re.search(r"No module named 'lalamo'(\s|$|\")", message):
return "skip", "lalamo not importable in this interpreter"
return "fail", message
def run_probe(name: str, code: str, extra: list[str] | None = None) -> tuple[str, str | None]:
"""Returns (pass|fail|skip, error)."""
try:
result = subprocess.run(
[sys.executable, "-c", code, *(extra or [])],
text=True,
capture_output=True,
timeout=180,
check=False,
)
except (OSError, subprocess.TimeoutExpired) as error:
return "fail", str(error)
if result.returncode == 0:
return "pass", None
message = (result.stderr or result.stdout or "").strip()[-400:] or "unknown failure"
# Only a missing top-level package is a skip. A missing submodule means the
# installed lalamo is the wrong tree (PyPI 0.17.0 has no compressed/
# incoherence.py), which must fail the gate instead of being skipped.
return classify_probe_failure(name, message)
def measure_probes(tokenizer_path: Path | None = None) -> tuple[dict, dict]:
results, errors = {}, {}
for name, code in PROBES.items():
extra = [str(tokenizer_path)] if name == "tokenizer" and tokenizer_path else None
if name == "tokenizer" and tokenizer_path is None:
results[name] = "skip"
continue
status, error = run_probe(name, code, extra)
results[name] = status
if error:
errors[name] = error
return results, errors
def disk_free_gib(path: Path) -> float:
try:
usage = shutil.disk_usage(path)
except OSError:
return -1.0
return round(usage.free / 1024**3, 1)
def kit_commit(root: Path) -> str | None:
manifest = root / "kit_manifest.json"
if manifest.exists():
try:
return json.loads(manifest.read_text(encoding="utf-8")).get("built_from_commit")
except json.JSONDecodeError:
return None
return None
def main() -> None:
parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
parser.add_argument("--json", type=Path, default=None)
parser.add_argument("--strict", action="store_true", help="exit 1 if BF16 matmul is unavailable")
parser.add_argument("--skip-bf16", action="store_true", help="do not import jax / lalamo")
parser.add_argument("--tokenizer", type=Path, default=None, help="tokenizer.json for the round-trip probe")
args = parser.parse_args()
try:
nvidia = subprocess.run(
["nvidia-smi", "--query-gpu=compute_cap,name", "--format=csv,noheader"],
text=True,
capture_output=True,
check=False,
timeout=20,
)
nvidia_stdout = (nvidia.stdout or "") if nvidia.returncode == 0 else ""
except (OSError, subprocess.TimeoutExpired):
nvidia_stdout = ""
capabilities = parse_capabilities(nvidia_stdout)
tokenizer_path = args.tokenizer
if tokenizer_path is None:
for candidate in Path("/kaggle/input").rglob("tokenizer.json"):
tokenizer_path = candidate
break
if args.skip_bf16:
probes, probe_errors = {}, {}
else:
probes, probe_errors = measure_probes(tokenizer_path)
report = {
"jax_platform": os.environ.get("JAX_PLATFORM_NAME"),
"compute_capabilities": capabilities,
"gpu_names": [line.split(",")[-1].strip() for line in nvidia_stdout.splitlines() if line.strip()],
"probe_errors": probe_errors if not args.skip_bf16 else {},
"disk_free_gib": disk_free_gib(Path("/kaggle/working")) if Path("/kaggle/working").exists() else disk_free_gib(Path(".")),
"kit_commit": kit_commit(Path("kit")),
}
report.update(verdict(capabilities, probes))
try:
from env_fingerprint import fingerprint
report["environment"] = fingerprint()
except Exception: # noqa: BLE001 - older kits may not ship env_fingerprint.py
report["environment"] = {}
report["jax_version"] = None
try:
from importlib.metadata import version
report["jax_version"] = version("jax")
except Exception: # noqa: BLE001
pass
print(json.dumps(report, indent=2, ensure_ascii=False))
if args.json:
args.json.parent.mkdir(parents=True, exist_ok=True)
args.json.write_text(json.dumps(report, indent=2, ensure_ascii=False) + "\n", encoding="utf-8")
if args.strict and not report["bf16_matmul"]:
raise SystemExit(1)
if __name__ == "__main__":
main()