[XPU] Use torch scaled_mm for XPU block FP8 linear (#35605)

This commit is contained in:
Cao E
2026-09-16 10:10:31 +08:00
committed by GitHub
parent 2cb51f5d22
commit f11cd8ab0e
3 changed files with 416 additions and 1 deletions
@@ -0,0 +1,336 @@
"""
SGLang XPU backend integration tests for FP8 scaled_mm linear paths.
Usage:
python3 -m unittest test.registered.e2e.xpu.test_xpu_fp8_linear
pytest test/registered/e2e/xpu/test_xpu_fp8_linear.py
"""
import unittest
from typing import List
import torch
from sglang.srt.layers.quantization.fp8_utils import (
dispatch_w8a8_block_fp8_linear,
per_token_group_quant_fp8,
torch_w8a8_block_fp8_linear,
)
from sglang.test.ci.ci_register import register_xpu_ci
from sglang.test.test_utils import CustomTestCase
register_xpu_ci(est_time=20, suite="stage-b-test-1-gpu-xpu")
def reference_block_fp8_matmul(
q_input: torch.Tensor,
activation_scale: torch.Tensor,
weight: torch.Tensor,
block_size: List[int],
weight_scale: torch.Tensor,
bias: torch.Tensor = None,
) -> torch.Tensor:
"""Reference using the exact quantized operands passed to scaled_mm."""
block_n, block_k = block_size
# Dequantize A: q_input [M, K], activation_scale [M, K // block_k]
M, K = q_input.shape
scale_a_expanded = (
activation_scale.unsqueeze(-1).expand(M, K // block_k, block_k).reshape(M, K)
)
a_dequant = q_input.float() * scale_a_expanded.float()
# Dequantize B: weight [N, K], weight_scale [N // block_n, K // block_k]
N = weight.shape[0]
scale_b_expanded = (
weight_scale.unsqueeze(1)
.unsqueeze(-1)
.expand(N // block_n, block_n, K // block_k, block_k)
.reshape(N, K)
)
b_dequant = weight.float() * scale_b_expanded.float()
output = torch.matmul(a_dequant, b_dequant.t())
if bias is not None:
output = output + bias.float()
return output
class TestXPUFP8Linear(CustomTestCase):
def setUp(self):
if not torch.xpu.is_available():
self.skipTest("XPU is not available")
self.device = "xpu"
def test_w8a8_block_fp8_dispatch_on_xpu(self):
"""Verify that dispatch_w8a8_block_fp8_linear cleanly routes to torch_w8a8_block_fp8_linear on XPU."""
dispatched_fn = dispatch_w8a8_block_fp8_linear()
self.assertIs(dispatched_fn, torch_w8a8_block_fp8_linear)
def test_torch_w8a8_block_fp8_linear_shapes_and_dims(self):
"""Test small sizes with varied M, 2D/3D shapes, and bias to keep memory minimal."""
K, N = 256, 256
block_size = [128, 128]
# Weights: [N, K], weight_scale: [N // 128, K // 128]
weight = torch.randn(N, K, dtype=torch.bfloat16, device=self.device).to(
torch.float8_e4m3fn
)
weight_scale = (
torch.rand(N // 128, K // 128, dtype=torch.float32, device=self.device)
+ 0.1
)
bias = torch.randn(N, dtype=torch.bfloat16, device=self.device)
# 1. 2D inputs with different M (decode M=1, small batch M=8, unaligned M=17)
for M in [1, 8, 17]:
x_2d = torch.randn(M, K, dtype=torch.bfloat16, device=self.device)
out_no_bias = torch_w8a8_block_fp8_linear(
x_2d, weight, block_size, weight_scale
)
self.assertEqual(out_no_bias.shape, (M, N))
self.assertEqual(out_no_bias.dtype, torch.bfloat16)
out_bias = torch_w8a8_block_fp8_linear(
x_2d, weight, block_size, weight_scale, bias=bias
)
self.assertEqual(out_bias.shape, (M, N))
torch.testing.assert_close(
out_bias, out_no_bias + bias, atol=0.05, rtol=0.01
)
# 2. 3D input: [Batch, SeqLen, Hidden]
x_3d = torch.randn(2, 4, K, dtype=torch.bfloat16, device=self.device)
out_3d = torch_w8a8_block_fp8_linear(x_3d, weight, block_size, weight_scale)
self.assertEqual(out_3d.shape, (2, 4, N))
x_3d_noncontiguous = x_3d.transpose(0, 1)
out_3d_noncontiguous = torch_w8a8_block_fp8_linear(
x_3d_noncontiguous, weight, block_size, weight_scale
)
self.assertEqual(out_3d_noncontiguous.shape, (4, 2, N))
def test_torch_w8a8_block_fp8_linear_prequantized(self):
"""Test pre-quantized input branch (input_scale is not None)."""
M, K, N = 16, 256, 256
block_size = [128, 128]
block_k = block_size[1]
x_bf16 = torch.randn(M, K, dtype=torch.bfloat16, device=self.device)
q_input, input_scale = per_token_group_quant_fp8(x_bf16, block_k)
weight = torch.randn(N, K, dtype=torch.bfloat16, device=self.device).to(
torch.float8_e4m3fn
)
weight_scale = (
torch.rand(N // 128, K // 128, dtype=torch.float32, device=self.device)
+ 0.1
)
out = torch_w8a8_block_fp8_linear(
q_input, weight, block_size, weight_scale, input_scale=input_scale
)
self.assertEqual(out.shape, (M, N))
self.assertEqual(out.dtype, torch.bfloat16)
scale_a = (
input_scale.unsqueeze(-1).expand(M, K // block_k, block_k).reshape(M, K)
)
scale_b = (
weight_scale.unsqueeze(1)
.unsqueeze(-1)
.expand(N // 128, 128, K // 128, 128)
.reshape(N, K)
)
ref = torch.matmul(
q_input.float() * scale_a.float(),
(weight.float() * scale_b.float()).t(),
).to(torch.bfloat16)
torch.testing.assert_close(out, ref, rtol=0.05, atol=0.1)
def test_torch_w8a8_block_fp8_linear_non_contiguous_views(self):
"""Test that pre-quantized non-contiguous slice views are handled safely without crash."""
M, K, N = 16, 256, 256
block_size = [128, 128]
x = torch.randn(M * 2, K, dtype=torch.bfloat16, device=self.device)
qx, scale = per_token_group_quant_fp8(x, block_size[1])
qx_strided = qx[::2, :]
scale_strided = scale[::2, :]
self.assertFalse(qx_strided.is_contiguous())
self.assertFalse(scale_strided.is_contiguous())
weight = torch.randn(N, K, dtype=torch.bfloat16, device=self.device).to(
torch.float8_e4m3fn
)
weight_scale = (
torch.rand(N // 128, K // 128, dtype=torch.float32, device=self.device)
+ 0.1
)
out_q_strided = torch_w8a8_block_fp8_linear(
qx_strided,
weight,
block_size,
weight_scale,
input_scale=scale_strided.contiguous(),
)
self.assertEqual(out_q_strided.shape, (M, N))
out_scale_strided = torch_w8a8_block_fp8_linear(
qx_strided.contiguous(),
weight,
block_size,
weight_scale,
input_scale=scale_strided,
)
torch.testing.assert_close(out_scale_strided, out_q_strided)
scale_transpose_contiguous = scale_strided.t().contiguous().t()
self.assertFalse(scale_transpose_contiguous.is_contiguous())
self.assertTrue(scale_transpose_contiguous.t().is_contiguous())
out_scale_transpose_contiguous = torch_w8a8_block_fp8_linear(
qx_strided.contiguous(),
weight,
block_size,
weight_scale,
input_scale=scale_transpose_contiguous,
)
torch.testing.assert_close(out_scale_transpose_contiguous, out_q_strided)
weight_noncontiguous = torch.empty(
N * 2, K, dtype=torch.float8_e4m3fn, device=self.device
)
weight_noncontiguous[::2] = weight
weight_noncontiguous = weight_noncontiguous[::2]
self.assertFalse(weight_noncontiguous.is_contiguous())
self.assertEqual(weight_noncontiguous.stride(-1), 1)
weight_scale_noncontiguous = weight_scale.t().contiguous().t()
out_weight_views = torch_w8a8_block_fp8_linear(
qx_strided.contiguous(),
weight_noncontiguous,
block_size,
weight_scale_noncontiguous,
input_scale=scale_strided.contiguous(),
)
self.assertEqual(out_weight_views.shape, (M, N))
torch.testing.assert_close(out_weight_views, out_q_strided)
weight_last_dim_strided = torch.empty(
N, K, 2, dtype=torch.float8_e4m3fn, device=self.device
)
weight_last_dim_strided[..., 0] = weight
weight_last_dim_strided = weight_last_dim_strided[..., 0]
self.assertFalse(weight_last_dim_strided.is_contiguous())
self.assertNotEqual(weight_last_dim_strided.stride(-1), 1)
out_weight_strided = torch_w8a8_block_fp8_linear(
qx_strided.contiguous(),
weight_last_dim_strided,
block_size,
weight_scale,
input_scale=scale_strided.contiguous(),
)
torch.testing.assert_close(out_weight_strided, out_q_strided)
def test_torch_w8a8_block_fp8_linear_rejects_invalid_block_size(self):
x = torch.randn(8, 256, dtype=torch.bfloat16, device=self.device)
weight = torch.randn(256, 256, dtype=torch.bfloat16, device=self.device).to(
torch.float8_e4m3fn
)
weight_scale = torch.ones(2, 2, dtype=torch.float32, device=self.device)
for block_size in ([], [128], [128, 128, 128], [1, 32], [64, 64]):
with self.subTest(block_size=block_size), self.assertRaises(ValueError):
torch_w8a8_block_fp8_linear(x, weight, block_size, weight_scale)
def test_torch_w8a8_block_fp8_linear_non_square_weight_scale(self):
"""Keep the public v2 weight-scale orientation correct when N != K."""
M, K, N = 8, 256, 384
block_size = [128, 128]
x = torch.randn(M, K, dtype=torch.bfloat16, device=self.device)
weight = torch.randn(N, K, dtype=torch.bfloat16, device=self.device).to(
torch.float8_e4m3fn
)
weight_scale = (
torch.rand(N // 128, K // 128, dtype=torch.float32, device=self.device)
+ 0.1
)
out = torch_w8a8_block_fp8_linear(x, weight, block_size, weight_scale)
q_input, input_scale = per_token_group_quant_fp8(x, block_size[1])
ref = reference_block_fp8_matmul(
q_input, input_scale, weight, block_size, weight_scale
).to(torch.bfloat16)
self.assertEqual(out.shape, (M, N))
torch.testing.assert_close(out, ref, rtol=0.05, atol=0.1)
def test_torch_w8a8_block_fp8_linear_numerical_accuracy(self):
"""Compare torch_w8a8_block_fp8_linear with dequantized baseline on XPU."""
M, K, N = 16, 256, 256
block_size = [128, 128]
x = torch.randn(M, K, dtype=torch.bfloat16, device=self.device)
weight = torch.randn(N, K, dtype=torch.bfloat16, device=self.device).to(
torch.float8_e4m3fn
)
weight_scale = (
torch.rand(N // 128, K // 128, dtype=torch.float32, device=self.device)
+ 0.1
)
bias = torch.randn(N, dtype=torch.bfloat16, device=self.device)
out_torch = torch_w8a8_block_fp8_linear(
x, weight, block_size, weight_scale, bias=bias
)
weight_scale_post_load = torch.empty_strided(
weight_scale.shape,
(1, weight_scale.shape[0]),
dtype=weight_scale.dtype,
device=weight_scale.device,
)
weight_scale_post_load.copy_(weight_scale)
out_post_load = torch_w8a8_block_fp8_linear(
x, weight, block_size, weight_scale_post_load, bias=bias
)
torch.testing.assert_close(out_post_load, out_torch, rtol=0, atol=0)
q_input, input_scale = per_token_group_quant_fp8(x, block_size[1])
out_ref = reference_block_fp8_matmul(
q_input, input_scale, weight, block_size, weight_scale, bias=bias
).to(torch.bfloat16)
torch.testing.assert_close(out_torch, out_ref, rtol=0.05, atol=0.1)
def test_torch_w8a8_block_fp8_linear_1x128_recipe(self):
"""Validate the alternate [1, 128] weight-scale recipe with N != K."""
M, K, N = 8, 256, 384
block_size = [1, 128]
x = torch.randn(M, K, dtype=torch.bfloat16, device=self.device)
weight = torch.randn(N, K, dtype=torch.bfloat16, device=self.device).to(
torch.float8_e4m3fn
)
weight_scale = (
torch.rand(N, K // 128, dtype=torch.float32, device=self.device) + 0.1
)
bias = torch.randn(N, dtype=torch.bfloat16, device=self.device)
out = torch_w8a8_block_fp8_linear(
x, weight, block_size, weight_scale, bias=bias
)
weight_scale_post_load = torch.empty_strided(
weight_scale.shape,
(1, weight_scale.shape[0]),
dtype=weight_scale.dtype,
device=weight_scale.device,
)
weight_scale_post_load.copy_(weight_scale)
out_post_load = torch_w8a8_block_fp8_linear(
x, weight, block_size, weight_scale_post_load, bias=bias
)
torch.testing.assert_close(out_post_load, out, rtol=0, atol=0)
q_input, input_scale = per_token_group_quant_fp8(x, block_size[1])
ref = reference_block_fp8_matmul(
q_input, input_scale, weight, block_size, weight_scale, bias
).to(torch.bfloat16)
torch.testing.assert_close(out, ref, rtol=0.05, atol=0.1)
if __name__ == "__main__":
unittest.main()