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sglang/test/registered/quant/test_nvfp4_embedding.py
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#!/usr/bin/env python3
import unittest
import torch
from sglang.srt.layers.quantization.modelopt_quant import (
ModelOptFp4Config,
ModelOptNvFp4EmbeddingMethod,
)
from sglang.test.ci.ci_register import register_cpu_ci
from sglang.test.test_utils import CustomTestCase
register_cpu_ci(est_time=10, suite="base-a-test-cpu")
GROUP_SIZE = 16
# Written out independently of the implementation: the E2M1 code points in
# magnitude order, so index == the 3-bit magnitude code.
_REFERENCE_E2M1 = [0.0, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0]
def reference_dequant(
packed: torch.Tensor, block_scale: torch.Tensor, global_scale: float
) -> torch.Tensor:
"""Comparison oracle. Kept as a plain per-element loop on purpose: a
vectorized rewrite would mirror the code under test."""
rows, half = packed.shape
hidden = half * 2
out = torch.zeros(rows, hidden, dtype=torch.float32)
for r in range(rows):
for c in range(hidden):
byte = int(packed[r, c // 2])
code = (byte & 0x0F) if c % 2 == 0 else (byte >> 4)
magnitude = _REFERENCE_E2M1[code & 0x7]
value = -magnitude if code & 0x8 else magnitude
scale = float(block_scale[r, c // GROUP_SIZE]) * global_scale
out[r, c] = value * scale
return out
def build_layer(method, vocab_size: int, hidden_size: int) -> torch.nn.Module:
"""Materialize through create_weights, then fill as a checkpoint would."""
layer = torch.nn.Module()
method.create_weights(
layer,
input_size_per_partition=hidden_size,
output_partition_sizes=[vocab_size],
input_size=hidden_size,
output_size=vocab_size,
params_dtype=torch.bfloat16,
)
generator = torch.Generator().manual_seed(0)
layer.weight.data.copy_(
torch.randint(
0,
256,
(vocab_size, hidden_size // 2),
dtype=torch.uint8,
generator=generator,
)
)
# Keep the block scales in a range e4m3 represents exactly.
layer.weight_scale.data.copy_(
torch.randint(
1,
8,
(vocab_size, hidden_size // GROUP_SIZE),
dtype=torch.int32,
generator=generator,
).to(torch.float8_e4m3fn)
)
layer.weight_scale_2.data.fill_(0.125)
return layer
class TestNvFp4Embedding(CustomTestCase):
def setUp(self):
self.method = ModelOptNvFp4EmbeddingMethod(
ModelOptFp4Config(
is_checkpoint_nvfp4_serialized=True, group_size=GROUP_SIZE
)
)
def test_matches_reference_dequant(self):
vocab_size, hidden_size = 24, 64
layer = build_layer(self.method, vocab_size, hidden_size)
self.assertEqual(tuple(layer.weight.shape), (vocab_size, hidden_size // 2))
self.assertEqual(
tuple(layer.weight_scale.shape), (vocab_size, hidden_size // GROUP_SIZE)
)
ids = torch.tensor([[0, 5, 5], [23, 11, 0]])
got = self.method.embedding(layer, ids)
expected = reference_dequant(
layer.weight[ids.reshape(-1)],
layer.weight_scale[ids.reshape(-1)].float(),
float(layer.weight_scale_2),
)
self.assertEqual(tuple(got.shape), (2, 3, hidden_size))
self.assertEqual(got.dtype, torch.bfloat16)
torch.testing.assert_close(
got.reshape(-1, hidden_size).float(),
expected.to(torch.bfloat16).float(),
rtol=0,
atol=0,
)
def test_hidden_size_must_divide_group_size(self):
with self.assertRaisesRegex(ValueError, "divisible by 16"):
self.method.create_weights(
torch.nn.Module(),
input_size_per_partition=40,
output_partition_sizes=[8],
input_size=40,
output_size=8,
params_dtype=torch.bfloat16,
)
if __name__ == "__main__":
unittest.main(verbosity=2)