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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import pytest
import torch
from vllm.model_executor.kernels.linear.mixed_precision.MPLinearKernel import (
MPLinearKernel,
)
from vllm.model_executor.parameter import (
ModelWeightParameter,
PackedvLLMParameter,
permute_param_layout_,
)
from vllm.model_executor.utils import replace_parameter
@pytest.fixture
def single_rank_tp(monkeypatch: pytest.MonkeyPatch) -> None:
"""`BasevLLMParameter.__init__` queries the TP group, which is not
initialized in a unit test. Pin it to a single rank.
"""
monkeypatch.setattr(
"vllm.model_executor.parameter.get_tensor_model_parallel_rank", lambda: 0
)
monkeypatch.setattr(
"vllm.model_executor.parameter.get_tensor_model_parallel_world_size", lambda: 1
)
@pytest.mark.parametrize("wrap_in_parameter", [False, True])
def test_replace_parameter_preserves_custom_attribute(wrap_in_parameter: bool) -> None:
"""`replace_parameter` must carry over attributes attached to the
replacement tensor (e.g. the `is_shuffled` flag set by AITER weight
preprocessing in `Fp8MoEMethod.process_weights_after_loading`).
The replacement is passed both as a plain `torch.Tensor` and as a
`torch.nn.Parameter`, since the latter is unwrapped through `.data`
internally, which does not carry attributes over either.
"""
layer = torch.nn.Module()
layer.register_parameter(
"weight", torch.nn.Parameter(torch.zeros(4, 4), requires_grad=False)
)
original = layer.weight
new_data: torch.Tensor = torch.ones(4, 4).t()
if wrap_in_parameter:
new_data = torch.nn.Parameter(new_data, requires_grad=False)
new_data.is_shuffled = True
# Sanity check on the assumption above: tensor internals are not
# reachable through `__dict__`, only user-set custom attributes are.
assert new_data.__dict__.keys() == {"is_shuffled"}
replace_parameter(layer, "weight", new_data)
assert isinstance(layer.weight, torch.nn.Parameter)
assert layer.weight.is_shuffled is True
assert torch.equal(layer.weight.data, new_data)
assert layer.weight.device == new_data.device
assert layer.weight is original
assert layer.weight.stride() == new_data.stride()
assert layer.weight.data_ptr() == new_data.data_ptr()
@pytest.mark.parametrize(
"new_data,copies",
[
(torch.ones(4, 4, dtype=torch.float32, device="cpu"), True),
(torch.ones(4, 4, dtype=torch.float32, device="cpu").t(), False),
(torch.ones(8, 4, dtype=torch.float32, device="cpu"), False),
(torch.ones(4, 4, dtype=torch.bfloat16, device="cpu"), False),
],
ids=["same-layout-copies", "new-strides", "new-shape", "new-dtype"],
)
def test_replace_parameter_keeps_object_by_default(
single_rank_tp: None, new_data: torch.Tensor, copies: bool
) -> None:
def weight_loader(param: torch.Tensor, loaded_weight: torch.Tensor) -> None:
pass
layer = torch.nn.Module()
old_param = ModelWeightParameter(
data=torch.zeros(4, 4, dtype=torch.float32, device="cpu"),
input_dim=1,
output_dim=0,
weight_loader=weight_loader,
)
layer.register_parameter("weight", old_param)
old_data_ptr = old_param.data_ptr()
replace_parameter(layer, "weight", new_data)
assert layer.weight is old_param
assert layer.weight.weight_loader is weight_loader
assert (layer.weight.input_dim, layer.weight.output_dim) == (1, 0)
assert layer.weight.dtype == new_data.dtype
assert layer.weight.stride() == new_data.stride()
assert torch.equal(layer.weight.data, new_data)
# Copying in place keeps addresses captured in CUDA graphs valid.
assert (layer.weight.data_ptr() == old_data_ptr) == copies
def test_replace_parameter_preserves_weight_loader() -> None:
"""The reload path must survive replacement: the old parameter's
`weight_loader` is carried over as-is, so it is still invoked as
`weight_loader(param, loaded_weight)`.
Real loaders are frequently bound methods of the layer (`RoutedExperts`
hands `self.weight_loader` to `create_weights`); what must not happen is
the carry-over re-binding the loader to the new parameter, which would
shift `loaded_weight` into the `param` slot.
"""
calls: list[tuple[torch.Tensor, torch.Tensor]] = []
def weight_loader(param: torch.Tensor, loaded_weight: torch.Tensor) -> None:
calls.append((param, loaded_weight))
layer = torch.nn.Module()
old_param = torch.nn.Parameter(torch.zeros(4, 4), requires_grad=False)
old_param.weight_loader = weight_loader
layer.register_parameter("weight", old_param)
replace_parameter(layer, "weight", torch.ones(4, 4))
# Re-binding to the new parameter would shift `loaded_weight` into the
# `param` slot, so the plain function must not have grown a `__self__`.
assert not hasattr(layer.weight.weight_loader, "__self__")
loaded_weight = torch.full((4, 4), 2.0)
layer.weight.weight_loader(layer.weight, loaded_weight)
assert len(calls) == 1
assert calls[0][0] is layer.weight
assert calls[0][1] is loaded_weight
def test_replace_parameter_weight_loader_comes_from_old_parameter() -> None:
"""`weight_loader` is deliberately excluded from the attribute carry-over:
the old parameter's loader is authoritative. A loader riding along on the
replacement tensor must neither shadow it nor trip the overwrite assertion
in `set_weight_attrs`, and the other attributes must still be carried over.
`_weight_loader` is excluded for the same reason: it is the backing field
of `BasevLLMParameter.weight_loader`, so leaving it in would smuggle a
stale loader past the `weight_loader` exclusion.
"""
calls: list[str] = []
def old_weight_loader(param: torch.Tensor, loaded_weight: torch.Tensor) -> None:
calls.append("old")
def stale_weight_loader(param: torch.Tensor, loaded_weight: torch.Tensor) -> None:
calls.append("stale")
layer = torch.nn.Module()
old_param = torch.nn.Parameter(torch.zeros(4, 4), requires_grad=False)
old_param.weight_loader = old_weight_loader
layer.register_parameter("weight", old_param)
new_data = torch.ones(4, 4)
new_data.weight_loader = stale_weight_loader
new_data._weight_loader = stale_weight_loader
new_data.is_shuffled = True
replace_parameter(layer, "weight", new_data)
layer.weight.weight_loader(layer.weight, torch.full((4, 4), 2.0))
assert calls == ["old"]
assert not hasattr(layer.weight, "_weight_loader")
assert layer.weight.is_shuffled is True
def test_replace_parameter_does_not_rebind_plain_function_attribute() -> None:
"""A plain function stored on the replacement tensor must be carried over
verbatim; re-binding it as a method of the new parameter would silently
shift the arguments of every subsequent call.
"""
def scale_for(group_size: int) -> int:
return group_size * 2
layer = torch.nn.Module()
layer.register_parameter(
"weight", torch.nn.Parameter(torch.zeros(4, 4), requires_grad=False)
)
new_data = torch.ones(4, 4)
new_data.scale_for = scale_for
replace_parameter(layer, "weight", new_data)
assert layer.weight.scale_for is scale_for
assert layer.weight.scale_for(3) == 6
def test_replace_parameter_preserves_bound_method_attribute() -> None:
"""A callable already bound to another object must keep pointing at that
object after replacement.
"""
class KernelDispatcher:
def __init__(self) -> None:
self.calls: list[int] = []
def record(self, value: int) -> None:
self.calls.append(value)
dispatcher = KernelDispatcher()
layer = torch.nn.Module()
layer.register_parameter(
"weight", torch.nn.Parameter(torch.zeros(4, 4), requires_grad=False)
)
new_data = torch.ones(4, 4)
new_data.record = dispatcher.record
replace_parameter(layer, "weight", new_data)
assert layer.weight.record.__self__ is dispatcher
layer.weight.record(7)
assert dispatcher.calls == [7]
def test_replace_parameter_registers_new_param_for_requantization_source() -> None:
layer = torch.nn.Module()
old_param = torch.nn.Parameter(torch.zeros(4, 4), requires_grad=False)
old_param.requantization_source = True
layer.register_parameter("weight", old_param)
replace_parameter(layer, "weight", torch.ones(4, 4))
assert layer.weight is not old_param
assert torch.equal(old_param, torch.zeros(4, 4))
assert torch.equal(layer.weight, torch.ones(4, 4))
def test_replace_parameter_with_own_parameter_keeps_layout(single_rank_tp) -> None:
"""Handing back the registered parameter keeps it unchanged."""
def weight_loader(param: torch.Tensor, loaded_weight: torch.Tensor) -> None:
pass
layer = torch.nn.Module()
old_param = PackedvLLMParameter(
data=torch.zeros(4, 4),
input_dim=1,
output_dim=0,
packed_dim=0,
packed_factor=8,
weight_loader=weight_loader,
)
layer.register_parameter("weight", old_param)
old_param.data = torch.ones(4, 4)
replace_parameter(layer, "weight", old_param)
assert layer.weight is old_param
assert type(layer.weight) is PackedvLLMParameter
assert layer.weight.weight_loader is weight_loader
assert (layer.weight.input_dim, layer.weight.output_dim) == (1, 0)
assert (layer.weight.packed_dim, layer.weight.packed_factor) == (0, 8)
assert torch.equal(layer.weight, torch.ones(4, 4))
def test_kept_param_ops_skip_python_torch_function(single_rank_tp: None) -> None:
"""Kept vLLM params must dispatch eager ops like a plain Parameter: a Python
`__torch_function__` would put every op on them through the interpreter."""
layer = torch.nn.Module()
layer.register_parameter(
"weight",
ModelWeightParameter(
data=torch.zeros(4, 4),
input_dim=1,
output_dim=0,
weight_loader=lambda param, loaded_weight: None,
),
)
replace_parameter(layer, "weight", torch.ones(4, 4))
assert type(layer.weight) is ModelWeightParameter
# A kept param must dispatch like a plain Parameter. Compare against a
# plain Parameter rather than asserting an absolute False: on ROCm,
# has_torch_function can return True for plain Parameters too.
plain = torch.nn.Parameter(torch.ones(4, 4))
assert torch.overrides.has_torch_function(
(layer.weight,)
) == torch.overrides.has_torch_function((plain,))
out = layer.weight + 1
assert type(out) is torch.Tensor
assert torch.equal(out, torch.full((4, 4), 2.0))
def test_transposed_kept_param_keeps_checkpoint_dims(single_rank_tp: None) -> None:
"""The loader shards a kept param by its dims on reload, so a kernel transform
that transposes it must not leave the post-transform dims on it."""
layer = torch.nn.Module()
weight = ModelWeightParameter(
data=torch.arange(6.0).view(2, 3),
input_dim=1,
output_dim=0,
weight_loader=lambda param, loaded_weight: None,
)
layer.register_parameter("weight", weight)
MPLinearKernel._transform_param(
None, # type: ignore[arg-type]
layer,
"weight",
lambda x: permute_param_layout_(x, input_dim=0, output_dim=1),
)
assert layer.weight is weight
assert torch.equal(weight, torch.arange(6.0).view(2, 3).t())
assert (weight.input_dim, weight.output_dim) == (1, 0)