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342 changes: 342 additions & 0 deletions benchmark/gemm/frost/benchmark_matmul_sm120.py
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# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0

"""Multi-library GEMM comparison for the frost sm120 matmul.

Benchmarks C = A @ B^T (TN, BF16 in / FP32 accumulate / BF16 out) across a
fixed 27-shape (M, N, K) sweep and prints a per-shape TFLOPS table comparing:

frost the sm120_matmul_1ctamma template (this repo)
cuBLAS torch.matmul (cuBLASLt)
CUTLASS classic CUTLASS python op (if installed)
TensorRT a single-MatMul engine (if installed)
b12x local-inference-lab/b12x (if importable)
FlashInfer flashinfer (if installed and it exposes a BF16 dense GEMM)

Libraries that are unavailable on the machine are reported as SKIP with the
reason; the table renders whatever columns actually ran.

CUDA_VISIBLE_DEVICES=2 python benchmark/gemm/frost/benchmark_matmul_sm120.py
... --shapes 4096x4096x4096,8192x8192x8192 # subset
... --libs frost,cublas # subset of libraries
... --check # bit-exactness vs cuBLAS
"""

from __future__ import annotations

import argparse
import os
import sys
import time

import torch

sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
from benchmark_utils import time_ms_delayed, time_ms_events # noqa: E402

# The 27-shape sweep (M, N, K).
SHAPES: list[tuple[int, int, int]] = [(m, n, k) for m in (4096, 8192, 16384) for n in (4096, 8192, 16384) for k in (4096, 8192, 16384)]

LIBS = ["frost", "cublas", "cutlass", "tensorrt", "b12x", "flashinfer"]


class Skip(Exception):
"""Raised by an adapter when its library can't run on this machine."""


# ---------------------------------------------------------------------------
# Adapters. Each setup_<lib>(M, N, K, data) returns a zero-arg callable that
# launches one GEMM on the (a, b, c) buffers, or raises Skip(reason).
# Layout contract: a[1,M,K] and b[1,N,K] row-major (both K-major), c[1,M,N].
# Stream contract: the harness times torch's CURRENT (non-default) stream; a
# library that does not follow it must be handed that stream explicitly, or
# the timer measures an empty stream (torch/flashinfer follow it by default).
# ---------------------------------------------------------------------------


def setup_frost(M: int, N: int, K: int, data, args):
import cudnn
import cudnn.gemm.frost # noqa: F401 — installs the pygraph recorder hook
from cudnn.gemm.frost.compiler import jit_from_cudnn_graph
from cudnn.gemm.frost.tile_config import by_name

major, minor = torch.cuda.get_device_capability()
if not (120 <= major * 10 + minor < 130):
raise Skip(f"needs a consumer-Blackwell GPU (sm120..12x), have sm_{major}{minor}")

g = cudnn.pygraph(
io_data_type=cudnn.data_type.BFLOAT16,
intermediate_data_type=cudnn.data_type.FLOAT,
compute_data_type=cudnn.data_type.FLOAT,
)
A = g.tensor(name="A", dim=[1, M, K], stride=[M * K, K, 1])
B = g.tensor(name="B", dim=[1, K, N], stride=[N * K, 1, K])
C = g.matmul(A=A, B=B, name="mm")
C.set_output(True)
compiled = jit_from_cudnn_graph(g, by_name(args.frost_config), cta_group=1)
a, b, c = data
bd = compiled.binding
pack = {bd.a_operands[0]: a, bd.b_operands[0]: b, bd.outputs[0]: c}
# A direct CompiledFusedGemm call launches on the DEFAULT stream when no
# stream is passed (the cuDNN-handle stream only arrives via engine
# dispatch), so hand it the harness stream.
stream = torch.cuda.current_stream().cuda_stream
return lambda: compiled(pack, stream=stream)


def setup_cublas(M: int, N: int, K: int, data, args):
a, b, c = data
bt = b.transpose(-1, -2)
return lambda: torch.matmul(a, bt, out=c)


def setup_cutlass(M: int, N: int, K: int, data, args):
# The classic CUTLASS python interface (package `nvidia-cutlass`, module
# cutlass.op). The nvidia-cutlass-dsl wheel installed alongside frost does
# NOT ship a prebuilt dense-GEMM op for sm120 (cutlass.utils.gemm only has
# sm100 tcgen05 helpers), so this probes for the classic API.
try:
import cutlass # noqa: F401
from cutlass.op import Gemm # type: ignore[attr-defined]
except Exception:
raise Skip("no CUTLASS python GEMM op (nvidia-cutlass-dsl has no sm120 dense-GEMM entry; pip install nvidia-cutlass for cutlass.op.Gemm)")
a, b, c = data
a2, b2, c2 = a[0], b[0].transpose(0, 1), c[0]
plan = Gemm(
A=a2,
B=b2,
C=c2,
D=c2,
alpha=1.0,
beta=0.0,
element_accumulator=torch.float32,
)
return lambda: plan.run(a2, b2, c2, c2, alpha=1.0, beta=0.0, sync=False)
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def setup_tensorrt(M: int, N: int, K: int, data, args):
try:
import tensorrt as trt
except Exception:
raise Skip("tensorrt not installed (pip install tensorrt)")
a, b, c = data
logger = trt.Logger(trt.Logger.WARNING)
builder = trt.Builder(logger)
# Strongly typed: BF16 flows from the input dtypes to the output. The
# weakly-typed route (BuilderFlag.BF16 + the ITensor.dtype setter) was
# deprecated in TRT 10 and removed in TRT 11.
network = builder.create_network(int(trt.NetworkDefinitionCreationFlag.STRONGLY_TYPED))
a_in = network.add_input("A", trt.DataType.BF16, (M, K))
b_in = network.add_input("B", trt.DataType.BF16, (N, K))
mm = network.add_matrix_multiply(a_in, trt.MatrixOperation.NONE, b_in, trt.MatrixOperation.TRANSPOSE)
out = mm.get_output(0)
out.name = "C"
network.mark_output(out)
config = builder.create_builder_config()
blob = builder.build_serialized_network(network, config)
if blob is None:
raise Skip("TensorRT engine build failed")
engine = trt.Runtime(logger).deserialize_cuda_engine(blob)
ctx = engine.create_execution_context()
ctx.set_tensor_address("A", a.data_ptr())
ctx.set_tensor_address("B", b.data_ptr())
ctx.set_tensor_address("C", c.data_ptr())
stream = torch.cuda.current_stream().cuda_stream
# Keep the engine/context alive via the closure.
return lambda _refs=(engine, ctx): ctx.execute_async_v3(stream)
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def setup_b12x(M: int, N: int, K: int, data, args):
# local-inference-lab / b12x. Not on PyPI: point PYTHONPATH (or --b12x-path)
# at the checkout, then adapt the entry-point probe below to its real API.
if args.b12x_path:
sys.path.insert(0, args.b12x_path)
mod = None
for name in ("b12x", "local_inference_lab.b12x", "local_inference_lab"):
try:
import importlib

mod = importlib.import_module(name)
break
except ImportError:
continue
if mod is None:
raise Skip("b12x not importable (clone local-inference-lab and pass --b12x-path)")
a, b, c = data
for entry in ("matmul", "gemm", "mm"):
fn = getattr(mod, entry, None)
if callable(fn):
return lambda _fn=fn: _fn(a[0], b[0], out=c[0])
raise Skip(f"b12x imported ({mod.__name__}) but exposes no known GEMM entry — adapt setup_b12x()")


def setup_flashinfer(M: int, N: int, K: int, data, args):
try:
from flashinfer.gemm import mm_bf16
except Exception:
raise Skip("flashinfer not installed or too old for gemm.mm_bf16 (pip install flashinfer-python)")
a, b, c = data
# mm_bf16 wants A (m, k) row-major and B (k, n) column-major — exactly the
# (N, K)-row-major buffer transposed.
a2, bt, c2 = a[0], b[0].transpose(0, 1), c[0]
# Its default backend='cudnn' can be broken independently of the others
# (e.g. a cuDNN sub-library mismatch), and 'auto' dies with it rather than
# falling back — so probe explicitly, first working backend wins.
backends = [args.flashinfer_backend] if args.flashinfer_backend else ["cublaslt", "cudnn", "cutlass", "tgv", "tinygemm"]
errs = []
for bk in backends:
run = lambda _bk=bk: mm_bf16(a2, bt, out=c2, backend=_bk)
try:
run()
torch.cuda.synchronize()
except Exception as e:
errs.append(f"{bk}: {str(e).splitlines()[0][:60]}")
continue
if not getattr(setup_flashinfer, "_noted", False):
print(f" [flashinfer: backend '{bk}']", flush=True)
setup_flashinfer._noted = True
return run
raise Skip("no working mm_bf16 backend — " + "; ".join(errs))


SETUP = {
"frost": setup_frost,
"cublas": setup_cublas,
"cutlass": setup_cutlass,
"tensorrt": setup_tensorrt,
"b12x": setup_b12x,
"flashinfer": setup_flashinfer,
}


# ---------------------------------------------------------------------------
# Harness
# ---------------------------------------------------------------------------


def _mkdata(M: int, N: int, K: int, check: bool):
torch.manual_seed(0)
if check:
# Small integers => exact FP32 reduction => bit-comparable outputs.
a = torch.empty(1, M, K, dtype=torch.int32).random_(-2, 2).to(dtype=torch.bfloat16, device="cuda")
b = torch.empty(1, N, K, dtype=torch.int32).random_(-2, 2).to(dtype=torch.bfloat16, device="cuda")
else:
a = torch.randn(1, M, K, device="cuda").to(torch.bfloat16)
b = torch.randn(1, N, K, device="cuda").to(torch.bfloat16)
c = torch.empty(1, M, N, dtype=torch.bfloat16, device="cuda")
return a, b, c


def _iters_for(flops: int) -> int:
# ~3e13 timed FLOP per measurement, clamped to [6, 50] iterations.
return max(6, min(50, int(3e13 // flops)))


def main() -> int:
parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
parser.add_argument("--libs", default=",".join(LIBS), help=f"comma list from {LIBS}")
parser.add_argument("--shapes", default="", help="comma list of MxNxK to run (default: the full 27-shape sweep)")
parser.add_argument("--warmup", type=int, default=5)
parser.add_argument("--iters", type=int, default=0, help="timed iterations (0 = auto-scale by FLOPs)")
parser.add_argument("--timing", choices=("delayed", "events"), default="delayed", help="delayed = kernel-only (host gaps hidden behind a CUDA sleep)")
parser.add_argument("--frost-config", default="CONFIG_sm120_128x128x128_128x128x32_cluster1x1")
parser.add_argument(
"--flashinfer-backend", default="", help="pin the mm_bf16 backend (cublaslt/cudnn/cutlass/tgv/tinygemm/cutile); default: probe in order"
)
parser.add_argument("--b12x-path", default=os.environ.get("B12X_PATH", ""), help="path to the local-inference-lab checkout for b12x")
parser.add_argument("--check", action="store_true", help="small-int inputs + compare every library bit-wise against cuBLAS")
parser.add_argument("--csv", default="", help="also write results to this CSV file")
args = parser.parse_args()

if not torch.cuda.is_available():
print("No CUDA device, exiting.")
return 1
# TRT's enqueueV3 inserts extra cudaStreamSynchronize calls on the DEFAULT
# stream (it warns about exactly this); a non-default stream keeps the
# delayed timer's back-to-back pipelining honest for every library.
torch.cuda.set_stream(torch.cuda.Stream())
libs = [x.strip() for x in args.libs.split(",") if x.strip()]
unknown = [x for x in libs if x not in SETUP]
if unknown:
sys.exit(f"unknown libs {unknown}; choose from {LIBS}")
if args.shapes:
shapes = []
for tok in args.shapes.split(","):
m, n, k = (int(x) for x in tok.lower().split("x"))
shapes.append((m, n, k))
else:
shapes = SHAPES

dev = torch.cuda.get_device_name()
cap = torch.cuda.get_device_capability()
timer = time_ms_delayed if args.timing == "delayed" else time_ms_events
print(f"GPU: {dev} (sm_{cap[0]}{cap[1]}) dtype: BF16 in / FP32 accum / BF16 out layout: TN (C = A @ B^T)")
print(f"timing: {args.timing}, warmup={args.warmup}, iters={'auto' if args.iters == 0 else args.iters}")

skip_reasons: dict[str, str] = {}
results: dict[tuple[int, int, int], dict[str, float]] = {}
t0 = time.time()

for M, N, K in shapes:
flops = 2 * M * N * K
iters = args.iters or _iters_for(flops)
data = _mkdata(M, N, K, args.check)
row: dict[str, float] = {}
ref = None
if args.check:
a, b, _ = data
ref = torch.matmul(a.to(torch.float32), b.transpose(-1, -2).to(torch.float32)).to(torch.bfloat16)
print(f"\n--- {M}x{N}x{K} ({flops / 1e12:.1f} TFLOP, iters={iters}) ---", flush=True)
for lib in libs:
if lib in skip_reasons:
continue
try:
run = SETUP[lib](M, N, K, data, args)
run()
torch.cuda.synchronize()
if ref is not None:
data[2].zero_()
run()
torch.cuda.synchronize()
bad = (data[2] != ref).sum().item()
if bad:
print(f" {lib:10s} CHECK FAILED: {bad} mismatches vs fp32 reference", flush=True)
ms = timer(lambda i, _r=run: _r(), lambda _r=run: _r(), warmup=args.warmup, iters=iters)
row[lib] = flops / (ms * 1e-3) / 1e12
print(f" {lib:10s} {row[lib]:8.2f} TFLOPS ({ms:.3f} ms)", flush=True)
except Skip as e:
skip_reasons[lib] = str(e)
print(f" {lib:10s} SKIP: {e}", flush=True)
except Exception as e:
msg = str(e).splitlines()[0][:70] if str(e) else type(e).__name__
row[lib] = float("nan")
print(f" {lib:10s} ERROR: {msg}", flush=True)
results[(M, N, K)] = row
del data
torch.cuda.empty_cache()

active = [l for l in libs if l not in skip_reasons]
width = 11
print("\n" + "=" * (22 + width * len(active)))
print(f" {'M x N x K':20s}" + "".join(f"{l:>{width}s}" for l in active))
print("=" * (22 + width * len(active)))
for (M, N, K), row in results.items():
cells = "".join(f"{row.get(l, float('nan')):>{width}.2f}" for l in active)
print(f" {f'{M}x{N}x{K}':20s}" + cells)
print("=" * (22 + width * len(active)))
print(" (TFLOPS; higher is better)")
for lib, why in skip_reasons.items():
print(f" SKIP {lib}: {why}")

if args.csv:
with open(args.csv, "w") as f:
f.write("M,N,K," + ",".join(active) + "\n")
for (M, N, K), row in results.items():
f.write(f"{M},{N},{K}," + ",".join(f"{row.get(l, float('nan')):.2f}" for l in active) + "\n")
print(f" CSV written to {args.csv}")
print(f"total: {time.time() - t0:.1f} s")
return 0


if __name__ == "__main__":
sys.exit(main())
2 changes: 1 addition & 1 deletion python/cudnn/gemm/frost/__init__.py
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
# Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: MIT

"""cudnn.gemm.frost: JIT fused sm100 GEMM kernels from cuDNN graphs via the CuTe DSL.
"""cudnn.gemm.frost: JIT fused GEMM kernels from cuDNN graphs via the CuTe DSL.

User code uses the plain cuDNN frontend API. The analyzer reads the python IR
(``graph.nodes``) directly; :class:`cudnn.gemm.frost.engine.FrostGemmEngine`
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