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vllm/tests/kernels/quantization/test_marlin_tile_padding.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Tests for Marlin thread-tile padding of TP-sharded weight shapes.
Run `pytest tests/kernels/quantization/test_marlin_tile_padding.py`.
"""
import pytest
import torch
from vllm import _custom_ops as ops
from vllm.model_executor.layers.quantization.utils.marlin_utils import (
GPTQ_MARLIN_TILE,
apply_gptq_marlin_linear,
marlin_make_empty_g_idx,
marlin_make_workspace_new,
marlin_pad_qweight,
marlin_pad_scales,
marlin_padded_nk,
marlin_permute_scales,
marlin_repacked_nk,
marlin_zero_points,
)
from vllm.model_executor.layers.quantization.utils.marlin_utils_fp4 import (
apply_fp4_marlin_linear,
is_fp4_marlin_supported,
prepare_fp4_layer_for_marlin,
)
from vllm.model_executor.layers.quantization.utils.marlin_utils_fp8 import (
apply_fp8_marlin_linear,
apply_mxfp8_marlin_linear,
is_fp8_marlin_supported,
prepare_fp8_layer_for_marlin,
prepare_mxfp8_layer_for_marlin,
)
from vllm.model_executor.layers.quantization.utils.quant_utils import (
gptq_pack,
gptq_quantize_weights,
quantize_weights,
)
from vllm.platforms import current_platform
from vllm.scalar_type import scalar_types
# (size_n, size_k) rank-local shapes that violate Marlin tile alignment,
# e.g. produced by TP-sharding dims that are valid at TP=1.
ODD_SHAPES = [
(200, 288), # N padded
(256, 208), # K padded
(200, 208), # both padded
(4640, 512), # Nemotron-Super-120B q_proj shard at TP=4
]
ALIGNED_SHAPES = [(64, 128), (128, 64), (256, 256), (4608, 4096)]
def _is_tile_aligned(size_n: int, size_k: int) -> bool:
return (size_n % 64 == 0 and size_k % 128 == 0) or (
size_n % 128 == 0 and size_k % 64 == 0
)
@pytest.mark.parametrize("shape", ODD_SHAPES + ALIGNED_SHAPES)
@pytest.mark.parametrize("group_size", [-1, 16, 32, 64, 128])
def test_marlin_padded_nk(shape, group_size):
size_n, size_k = shape
padded_n, padded_k = marlin_padded_nk(size_n, size_k, group_size)
assert padded_n >= size_n and padded_k >= size_k
assert _is_tile_aligned(padded_n, padded_k)
if group_size > 0:
assert padded_k % group_size == 0
# Aligned shapes must pass through unchanged (zero hot-path cost).
if _is_tile_aligned(size_n, size_k) and (
group_size <= 0 or size_k % group_size == 0
):
assert (padded_n, padded_k) == (size_n, size_k)
# Minimal: no valid shape with a smaller padded area exists.
area = padded_n * padded_k
for cand_n in range(size_n, padded_n + 1):
for cand_k in range(size_k, padded_k + 1):
if (
_is_tile_aligned(cand_n, cand_k)
and (group_size <= 0 or cand_k % group_size == 0)
and cand_n * cand_k < area
):
pytest.fail(f"({cand_n}, {cand_k}) beats ({padded_n}, {padded_k})")
# Apply-time derivation from the repacked-tensor shape must round-trip.
for num_bits in (4, 8):
pack_factor = 32 // num_bits
repacked_shape = (
padded_k // GPTQ_MARLIN_TILE,
padded_n * GPTQ_MARLIN_TILE // pack_factor,
)
repacked = torch.empty(repacked_shape, device="meta")
assert marlin_repacked_nk(repacked, num_bits) == (padded_n, padded_k)
def test_marlin_pad_helpers_shapes():
size_n, size_k, group_size = 200, 208, 16
padded_n, padded_k = marlin_padded_nk(size_n, size_k, group_size)
qweight = torch.zeros(size_k // 8, size_n, dtype=torch.int32)
padded = marlin_pad_qweight(qweight, size_n, size_k, padded_n, padded_k)
assert padded.shape == (padded_k // 8, padded_n)
scales = torch.ones(size_k // group_size, size_n)
padded = marlin_pad_scales(scales, size_n, size_k, padded_n, padded_k, group_size)
assert padded.shape == (padded_k // group_size, padded_n)
assert padded[:, size_n:].abs().sum() == 0
channelwise = torch.ones(1, size_n)
padded = marlin_pad_scales(channelwise, size_n, size_k, padded_n, padded_k, -1)
assert padded.shape == (1, padded_n)
def _gpu_marlin_unsupported() -> bool:
return not (
current_platform.is_cuda() and current_platform.has_device_capability(80)
)
@pytest.mark.skipif(
_gpu_marlin_unsupported() or not is_fp8_marlin_supported(),
reason="FP8 Marlin is not supported on this GPU type.",
)
@pytest.mark.parametrize("shape", ODD_SHAPES)
@pytest.mark.parametrize("use_bias", [False, True])
def test_fp8_marlin_padded_round_trip(shape, use_bias):
size_n, size_k = shape
dtype = torch.float16
layer = torch.nn.Module()
layer.output_size_per_partition = size_n
layer.input_size_per_partition = size_k
layer.orig_dtype = dtype
weight = torch.randn(size_k, size_n, dtype=dtype, device="cuda") / size_k**0.5
scale = weight.abs().max() / 448
weight_fp8 = (weight / scale).to(torch.float8_e4m3fn)
layer.weight = torch.nn.Parameter(weight_fp8, requires_grad=False)
layer.weight_scale = torch.nn.Parameter(
scale.to(torch.float32), requires_grad=False
)
bias = None
if use_bias:
bias = torch.randn(size_n, dtype=dtype, device="cuda")
layer.bias = torch.nn.Parameter(bias.clone(), requires_grad=False)
prepare_fp8_layer_for_marlin(layer, size_k_first=True)
x = torch.randn(8, size_k, dtype=dtype, device="cuda")
output = apply_fp8_marlin_linear(
input=x,
weight=layer.weight,
weight_scale=layer.weight_scale,
workspace=layer.workspace,
size_n=size_n,
size_k=size_k,
bias=layer.bias if use_bias else None,
)
ref = x @ (weight_fp8.to(dtype) * scale.to(dtype))
if use_bias:
ref = ref + bias
assert output.shape == (8, size_n)
torch.testing.assert_close(output, ref, rtol=2e-2, atol=2e-2)
def _dequant_fp4(packed: torch.Tensor, dtype: torch.dtype) -> torch.Tensor:
"""Dequantize packed e2m1 nibbles (N, K // 2) -> (N, K) in dtype."""
lo = (packed & 0b10000000) | ((packed & 0b01110000) >> 2)
lo = lo.view(torch.float8_e4m3fn).to(dtype) * (2**6)
hi_bits = packed << 4
hi = (hi_bits & 0b10000000) | ((hi_bits & 0b01110000) >> 2)
hi = hi.view(torch.float8_e4m3fn).to(dtype) * (2**6)
return torch.cat([hi.unsqueeze(2), lo.unsqueeze(2)], 2).view(packed.size(0), -1)
@pytest.mark.skipif(
_gpu_marlin_unsupported() or not is_fp4_marlin_supported(),
reason="FP4 Marlin is not supported on this GPU type.",
)
@pytest.mark.parametrize("shape", ODD_SHAPES)
def test_nvfp4_marlin_padded_round_trip(shape):
size_n, size_k = shape
group_size = 16
dtype = torch.float16
layer = torch.nn.Module()
layer.output_size_per_partition = size_n
layer.input_size_per_partition = size_k
layer.params_dtype = dtype
packed = torch.randint(
0, 256, (size_n, size_k // 2), dtype=torch.uint8, device="cuda"
)
scales = (torch.rand(size_n, size_k // group_size, device="cuda") + 0.25).to(
torch.float8_e4m3fn
)
global_scale = torch.tensor([0.002], dtype=torch.float32, device="cuda")
ref_weight = (
_dequant_fp4(packed, dtype)
* scales.to(dtype).repeat_interleave(group_size, 1)
* global_scale.to(dtype)
)
layer.weight = torch.nn.Parameter(packed, requires_grad=False)
layer.weight_scale = torch.nn.Parameter(scales, requires_grad=False)
layer.weight_global_scale = torch.nn.Parameter(global_scale, requires_grad=False)
prepare_fp4_layer_for_marlin(layer)
x = torch.randn(8, size_k, dtype=dtype, device="cuda") / size_k**0.5
output = apply_fp4_marlin_linear(
input=x,
weight=layer.weight,
weight_scale=layer.weight_scale,
weight_global_scale=layer.weight_global_scale,
workspace=layer.workspace,
size_n=size_n,
size_k=size_k,
)
ref = x @ ref_weight.T
assert output.shape == (8, size_n)
torch.testing.assert_close(output, ref, rtol=2e-2, atol=2e-2)
@pytest.mark.skipif(
_gpu_marlin_unsupported(),
reason="Marlin is not supported on this GPU type.",
)
@pytest.mark.parametrize("shape", ODD_SHAPES)
@pytest.mark.parametrize("group_size", [-1, 128])
def test_gptq_marlin_padded_round_trip(shape, group_size):
"""Pad-then-repack a GPTQ int4 weight the way MarlinLinearKernel does and
check the GEMM against the dequantized reference.
Symmetric int4's quantized zero decodes to -8, so this exercises the
zero-padded-scales cancellation, not just zero weights.
"""
size_n, size_k = shape
if group_size > 0 and size_k % group_size != 0:
pytest.skip("group must divide the rank-local K (not fixable by padding)")
dtype = torch.float16
quant_type = scalar_types.uint4b8
device = torch.device("cuda")
weight = torch.randn(size_k, size_n, dtype=dtype, device=device) / size_k**0.5
w_ref, q_w, s, _, _ = gptq_quantize_weights(
weight, quant_type, group_size, act_order=False
)
qweight = gptq_pack(q_w, quant_type.size_bits, size_k, size_n)
padded_n, padded_k = marlin_padded_nk(size_n, size_k, group_size)
qweight = marlin_pad_qweight(qweight, size_n, size_k, padded_n, padded_k)
marlin_qweight = ops.gptq_marlin_repack(
b_q_weight=qweight,
perm=torch.empty(0, dtype=torch.int, device=device),
size_k=padded_k,
size_n=padded_n,
num_bits=quant_type.size_bits,
)
s = marlin_pad_scales(s, size_n, size_k, padded_n, padded_k, group_size)
marlin_s = marlin_permute_scales(
s, size_k=padded_k, size_n=padded_n, group_size=group_size
)
x = torch.randn(8, size_k, dtype=dtype, device=device)
output = apply_gptq_marlin_linear(
input=x,
weight=marlin_qweight,
weight_scale=marlin_s,
weight_zp=marlin_make_empty_g_idx(device),
g_idx=marlin_make_empty_g_idx(device),
g_idx_sort_indices=marlin_make_empty_g_idx(device),
workspace=marlin_make_workspace_new(device),
wtype=quant_type,
output_size_per_partition=size_n,
input_size_per_partition=size_k,
is_k_full=True,
)
ref = x @ w_ref
assert output.shape == (8, size_n)
torch.testing.assert_close(output, ref, rtol=2e-2, atol=2e-2)
@pytest.mark.skipif(
_gpu_marlin_unsupported() or not is_fp8_marlin_supported(),
reason="FP8 Marlin is not supported on this GPU type.",
)
@pytest.mark.parametrize("shape", [(200, 512), (4640, 512)])
def test_fp8_block_marlin_padded_round_trip(shape):
"""Block-quantized FP8 (e.g. Nemotron NVFP4 checkpoints' FP8 layers):
group_size=128 exercises the lcm K-alignment in marlin_padded_nk and the
weight_scale_inv group-wise scale padding."""
size_n, size_k = shape
block = 128
dtype = torch.float16
layer = torch.nn.Module()
layer.output_size_per_partition = size_n
layer.input_size_per_partition = size_k
layer.orig_dtype = dtype
layer.weight_block_size = [block, block]
weight = torch.randn(size_n, size_k, dtype=dtype, device="cuda") / size_k**0.5
n_blocks, k_blocks = (size_n + block - 1) // block, size_k // block
padded = torch.zeros(n_blocks * block, size_k, dtype=dtype, device="cuda")
padded[:size_n] = weight
scales = padded.view(n_blocks, block, k_blocks, block).abs().amax(dim=(1, 3)) / 448
scales_expanded = scales.repeat_interleave(block, 0)[:size_n].repeat_interleave(
block, 1
)
weight_fp8 = (weight / scales_expanded).to(torch.float8_e4m3fn)
layer.weight = torch.nn.Parameter(weight_fp8, requires_grad=False)
layer.weight_scale_inv = torch.nn.Parameter(
scales.to(torch.float32), requires_grad=False
)
prepare_fp8_layer_for_marlin(layer, size_k_first=False)
x = torch.randn(8, size_k, dtype=dtype, device="cuda")
output = apply_fp8_marlin_linear(
input=x,
weight=layer.weight,
weight_scale=layer.weight_scale_inv,
workspace=layer.workspace,
size_n=size_n,
size_k=size_k,
bias=None,
)
ref = x @ (weight_fp8.to(dtype) * scales_expanded.to(dtype)).T
assert output.shape == (8, size_n)
torch.testing.assert_close(output, ref, rtol=2e-2, atol=2e-2)
@pytest.mark.skipif(
_gpu_marlin_unsupported() or not is_fp8_marlin_supported(),
reason="FP8 Marlin is not supported on this GPU type.",
)
@pytest.mark.parametrize("shape", [(200, 288), (4640, 512)])
def test_mxfp8_marlin_padded_round_trip(shape):
"""MXFP8 exercises the e8m0 scale path, where padded 0.0 scales clamp to
2^-127 instead of zero and must still contribute nothing."""
size_n, size_k = shape
group_size = 32
# The e8m0-scale Marlin kernels are only instantiated for bf16 activations.
dtype = torch.bfloat16
layer = torch.nn.Module()
layer.output_size_per_partition = size_n
layer.input_size_per_partition = size_k
weight_fp8 = (torch.randn(size_n, size_k, dtype=dtype, device="cuda") / 4).to(
torch.float8_e4m3fn
)
# e8m0 exponents around 1.0 (127): scales in [2^-6, 2^0]
scales = torch.randint(
121, 128, (size_n, size_k // group_size), dtype=torch.uint8, device="cuda"
)
ref_weight = weight_fp8.to(dtype) * (
2.0 ** (scales.to(dtype) - 127)
).repeat_interleave(group_size, 1)
layer.weight = torch.nn.Parameter(weight_fp8, requires_grad=False)
layer.weight_scale = torch.nn.Parameter(scales, requires_grad=False)
prepare_mxfp8_layer_for_marlin(layer)
x = torch.randn(8, size_k, dtype=dtype, device="cuda") / size_k**0.5
output = apply_mxfp8_marlin_linear(
input=x,
weight=layer.weight,
weight_scale=layer.weight_scale,
workspace=layer.workspace,
size_n=size_n,
size_k=size_k,
)
ref = x @ ref_weight.T
assert output.shape == (8, size_n)
torch.testing.assert_close(output, ref, rtol=2e-2, atol=2e-2)
@pytest.mark.skipif(
_gpu_marlin_unsupported(),
reason="Marlin is not supported on this GPU type.",
)
@pytest.mark.parametrize("shape", [(200, 512), (4640, 512)])
def test_awq_zp_marlin_padded_round_trip(shape):
"""AWQ-style uint4 with runtime zero-points, padded the way
MarlinLinearKernel does: padded columns rely on (q=0 - zp=0) * scale=0."""
size_n, size_k = shape
group_size = 128
dtype = torch.float16
quant_type = scalar_types.uint4
device = torch.device("cuda")
weight = torch.randn(size_k, size_n, dtype=dtype, device=device) / size_k**0.5
w_ref, q_w, s, zp = quantize_weights(
weight, quant_type, group_size, zero_points=True
)
qweight = gptq_pack(q_w, quant_type.size_bits, size_k, size_n)
padded_n, padded_k = marlin_padded_nk(size_n, size_k, group_size)
qweight = marlin_pad_qweight(qweight, size_n, size_k, padded_n, padded_k)
marlin_qweight = ops.gptq_marlin_repack(
b_q_weight=qweight,
perm=torch.empty(0, dtype=torch.int, device=device),
size_k=padded_k,
size_n=padded_n,
num_bits=quant_type.size_bits,
)
s = marlin_pad_scales(s, size_n, size_k, padded_n, padded_k, group_size)
marlin_s = marlin_permute_scales(
s, size_k=padded_k, size_n=padded_n, group_size=group_size
)
zp = marlin_pad_scales(zp, size_n, size_k, padded_n, padded_k, group_size)
marlin_zp = marlin_zero_points(
zp,
size_k=padded_k // group_size,
size_n=padded_n,
num_bits=quant_type.size_bits,
)
x = torch.randn(8, size_k, dtype=dtype, device=device)
output = apply_gptq_marlin_linear(
input=x,
weight=marlin_qweight,
weight_scale=marlin_s,
weight_zp=marlin_zp,
g_idx=marlin_make_empty_g_idx(device),
g_idx_sort_indices=marlin_make_empty_g_idx(device),
workspace=marlin_make_workspace_new(device),
wtype=quant_type,
output_size_per_partition=size_n,
input_size_per_partition=size_k,
is_k_full=True,
)
ref = x @ w_ref
assert output.shape == (8, size_n)
torch.testing.assert_close(output, ref, rtol=2e-2, atol=2e-2)
class _FakeLinear:
def __init__(self, size_n, size_k, input_size=None):
self.output_size_per_partition = size_n
self.input_size_per_partition = size_k
self.output_size = size_n
self.input_size = input_size if input_size is not None else size_k
def test_check_marlin_supports_layer_allow_tile_padding():
from vllm.model_executor.layers.quantization.utils.marlin_utils import (
check_marlin_supports_layer,
)
# Tile-misaligned but group-aligned: rejected strictly, allowed w/ padding
layer = _FakeLinear(4640, 512, input_size=2048)
assert not check_marlin_supports_layer(layer, 128)
assert check_marlin_supports_layer(layer, 128, allow_tile_padding=True)
assert check_marlin_supports_layer(layer, -1, allow_tile_padding=True)
# A group straddling the TP shard cannot be fixed by padding
layer = _FakeLinear(4608, 4672, input_size=18688)
assert not check_marlin_supports_layer(layer, 128, allow_tile_padding=True)