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sglang/python/sglang/srt/layers/fused_moe/layer.py

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Python

# Adapted from
# https://github.com/vllm-project/vllm/tree/v0.5.4/vllm/model_executor/layers/fused_moe
import os
from abc import abstractmethod
from typing import List, Optional, Tuple
import torch
import torch.nn.functional as F
from vllm.distributed import (
get_tensor_model_parallel_rank,
get_tensor_model_parallel_world_size,
tensor_model_parallel_all_reduce,
)
from vllm.logger import init_logger
from vllm.model_executor.custom_op import CustomOp
from vllm.model_executor.layers.quantization.base_config import (
QuantizationConfig,
QuantizeMethodBase,
)
from vllm.model_executor.layers.quantization.fp8 import Fp8Config
from vllm.model_executor.utils import set_weight_attrs
from sglang.srt.layers.fused_moe.fused_moe import padding_size
from sglang.srt.utils import is_hip
logger = init_logger(__name__)
class FusedMoEMethodBase(QuantizeMethodBase):
@abstractmethod
def create_weights(
self,
layer: torch.nn.Module,
num_experts: int,
hidden_size: int,
intermediate_size: int,
params_dtype: torch.dtype,
**extra_weight_attrs,
):
raise NotImplementedError
@abstractmethod
def apply(
self,
layer: torch.nn.Module,
x: torch.Tensor,
router_logits: torch.Tensor,
top_k: int,
renormalize: bool = True,
use_grouped_topk: bool = False,
num_expert_group: Optional[int] = None,
topk_group: Optional[int] = None,
) -> torch.Tensor:
raise NotImplementedError
class UnquantizedFusedMoEMethod(FusedMoEMethodBase, CustomOp):
"""MoE method without quantization."""
def create_weights(
self,
layer: torch.nn.Module,
num_experts: int,
hidden_size: int,
intermediate_size: int,
params_dtype: torch.dtype,
**extra_weight_attrs,
):
# Fused gate_up_proj (column parallel)
w13_weight = torch.nn.Parameter(
torch.empty(
num_experts, 2 * intermediate_size, hidden_size, dtype=params_dtype
),
requires_grad=False,
)
layer.register_parameter("w13_weight", w13_weight)
set_weight_attrs(w13_weight, extra_weight_attrs)
# down_proj (row parallel)
w2_weight = torch.nn.Parameter(
torch.empty(
num_experts, hidden_size, intermediate_size, dtype=params_dtype
),
requires_grad=False,
)
layer.register_parameter("w2_weight", w2_weight)
set_weight_attrs(w2_weight, extra_weight_attrs)
def apply(
self,
layer: torch.nn.Module,
x: torch.Tensor,
router_logits: torch.Tensor,
top_k: int,
renormalize: bool = True,
use_grouped_topk: bool = False,
num_expert_group: Optional[int] = None,
topk_group: Optional[int] = None,
) -> torch.Tensor:
return self.forward(
x,
layer.w13_weight,
layer.w2_weight,
router_logits,
top_k,
renormalize,
use_grouped_topk,
num_expert_group,
topk_group,
)
def forward_cuda(
self,
x: torch.Tensor,
w1: torch.Tensor,
w2: torch.Tensor,
router_logits: torch.Tensor,
top_k: int,
renormalize: bool,
use_grouped_topk: bool,
num_expert_group: Optional[int],
topk_group: Optional[int],
) -> torch.Tensor:
from sglang.srt.layers.fused_moe.fused_moe import fused_moe
return fused_moe(
x,
w1,
w2,
router_logits,
top_k,
renormalize=renormalize,
inplace=True,
use_grouped_topk=use_grouped_topk,
num_expert_group=num_expert_group,
topk_group=topk_group,
)
def forward_cpu(self, *args, **kwargs):
raise NotImplementedError("The CPU backend currently does not support MoE.")
def forward_tpu(
self,
x: torch.Tensor,
w1: torch.Tensor,
w2: torch.Tensor,
router_logits: torch.Tensor,
top_k: int,
renormalize: bool,
use_grouped_topk: bool,
num_expert_group: Optional[int],
topk_group: Optional[int],
) -> torch.Tensor:
from vllm.model_executor.layers.fused_moe.moe_pallas import fused_moe
assert not use_grouped_topk
assert num_expert_group is None
assert topk_group is None
return fused_moe(x, w1, w2, router_logits, top_k, renormalize)
class FusedMoE(torch.nn.Module):
"""FusedMoE layer for MoE models.
This layer contains both MergedColumnParallel weights (gate_up_proj /
w13) and RowParallelLinear weights (down_proj/ w2).
Note: Mixtral uses w1, w2, and w3 for gate, up, and down_proj. We
copy that naming convention here and handle any remapping in the
load_weights function in each model implementation.
Args:
num_experts: Number of experts in the model
top_k: Number of experts selected for each token
hidden_size: Input hidden state size of the transformer
intermediate_size: Intermediate size of the experts
params_dtype: Data type for the parameters.
reduce_results: Whether to all all_reduce on the output of the layer
renomalize: Whether to renormalize the logits in the fused_moe kernel
quant_config: Quantization configure.
"""
def __init__(
self,
num_experts: int,
top_k: int,
hidden_size: int,
intermediate_size: int,
params_dtype: Optional[torch.dtype] = None,
reduce_results: bool = False,
renormalize: bool = True,
use_grouped_topk: bool = False,
num_expert_group: Optional[int] = None,
topk_group: Optional[int] = None,
quant_config: Optional[QuantizationConfig] = None,
tp_size: Optional[int] = None,
prefix: str = "",
):
super().__init__()
if params_dtype is None:
params_dtype = torch.get_default_dtype()
self.tp_size = (
tp_size if tp_size is not None else get_tensor_model_parallel_world_size()
)
self.top_k = top_k
self.num_experts = num_experts
self.intermediate_size_per_partition = intermediate_size // self.tp_size
self.reduce_results = reduce_results
self.renormalize = renormalize
self.use_grouped_topk = use_grouped_topk
if self.use_grouped_topk:
assert num_expert_group is not None and topk_group is not None
self.num_expert_group = num_expert_group
self.topk_group = topk_group
if quant_config is None:
self.quant_method: Optional[QuantizeMethodBase] = (
UnquantizedFusedMoEMethod()
)
else:
if isinstance(quant_config, Fp8Config):
self.quant_method = Fp8MoEMethod(quant_config)
else:
self.quant_method = quant_config.get_quant_method(self, prefix)
assert self.quant_method is not None
self.quant_method.create_weights(
layer=self,
num_experts=num_experts,
hidden_size=hidden_size,
intermediate_size=self.intermediate_size_per_partition,
params_dtype=params_dtype,
weight_loader=self.weight_loader,
)
def weight_loader(
self,
param: torch.nn.Parameter,
loaded_weight: torch.Tensor,
weight_name: str,
shard_id: int,
expert_id: int,
use_presharded_weights: bool = False,
):
param_data = param.data
# Input scales can be loaded directly and should be equal.
if "input_scale" in weight_name:
if (
param_data[expert_id] != 1
and (param_data[expert_id] - loaded_weight).abs() > 1e-5
):
raise ValueError(
"input_scales of w1 and w3 of a layer "
f"must be equal. But got {param_data[expert_id]} "
f"vs. {loaded_weight}"
)
param_data[expert_id] = loaded_weight
# Weight scales
elif "weight_scale" in weight_name:
# If we are in merged column case (gate_up_proj)
# shard_id 0 == gate_proj / w1
# shard_id 2 == up_proj / w3
if shard_id == 0 or shard_id == 2:
# We have to keep the weight scales of w1 and w3 because
# we need to re-quantize w1/w3 weights after weight loading.
idx = 0 if shard_id == 0 else 1
param_data[expert_id][idx] = loaded_weight
# If we are in the row parallel case (down_proj)
# shard_id 1 == down_proj / w2
else:
param_data[expert_id] = loaded_weight
# Weights
else:
tp_rank = get_tensor_model_parallel_rank()
shard_size = self.intermediate_size_per_partition
if use_presharded_weights:
shard = slice(None)
else:
shard = slice(tp_rank * shard_size, (tp_rank + 1) * shard_size)
# w1, gate_proj case: Load into first shard of w13.
if shard_id == 0:
param_data[expert_id, 0:shard_size, :] = loaded_weight[shard, :]
# w3, up_proj case: Load into second shard of w13.
elif shard_id == 2:
param_data[expert_id, shard_size : 2 * shard_size, :] = loaded_weight[
shard, :
]
# w2, down_proj case: Load into only shard of w2.
elif shard_id == 1:
param_data[expert_id, :, :] = loaded_weight[:, shard]
else:
raise ValueError(f"Shard id must be in [0,1,2] but got {shard_id}")
def forward(self, hidden_states: torch.Tensor, router_logits: torch.Tensor):
assert self.quant_method is not None
# Matrix multiply.
final_hidden_states = self.quant_method.apply(
self,
x=hidden_states,
router_logits=router_logits,
top_k=self.top_k,
renormalize=self.renormalize,
use_grouped_topk=self.use_grouped_topk,
num_expert_group=self.num_expert_group,
topk_group=self.topk_group,
)
if self.reduce_results and self.tp_size > 1:
final_hidden_states = tensor_model_parallel_all_reduce(final_hidden_states)
return final_hidden_states
@classmethod
def make_expert_params_mapping(
cls,
ckpt_gate_proj_name: str,
ckpt_down_proj_name: str,
ckpt_up_proj_name: str,
num_experts: int,
) -> List[Tuple[str, str, int, int]]:
gate_up = [ckpt_gate_proj_name, ckpt_up_proj_name]
gate_down_up = [ckpt_gate_proj_name, ckpt_down_proj_name, ckpt_up_proj_name]
return (
[
# These are the weight scales for the experts
# (param_name, weight_name, expert_id, shard_id)
(
(
"experts.w13_scale"
if weight_name in gate_up
else "experts.w2_scale"
),
f"experts.{expert_id}.{weight_name}.weight_scale",
expert_id,
shard_id,
)
for expert_id in range(num_experts)
for shard_id, weight_name in enumerate(gate_down_up)
]
+ [
# These are the weights for the experts
# (param_name, weight_name, expert_id, shard_id)
(
(
"experts.w13_weight"
if weight_name in gate_up
else "experts.w2_weight"
),
f"experts.{expert_id}.{weight_name}.weight",
expert_id,
shard_id,
)
for expert_id in range(num_experts)
for shard_id, weight_name in enumerate(gate_down_up)
]
+ [
# These are the weight scales for the experts
# (param_name, weight_name, expert_id, shard_id)
(
(
"experts.a13_scale"
if weight_name in gate_up
else "experts.a2_scale"
),
f"experts.{expert_id}.{weight_name}.input_scale",
expert_id,
shard_id,
)
for expert_id in range(num_experts)
for shard_id, weight_name in enumerate(gate_down_up)
]
)
import torch
from torch.nn import Module
from vllm import _custom_ops as ops
from vllm.model_executor.layers.quantization.utils.w8a8_utils import (
all_close_1d,
normalize_e4m3fn_to_e4m3fnuz,
per_tensor_dequantize,
)
from vllm.utils import print_warning_once
class Fp8MoEMethod(FusedMoEMethodBase):
"""MoE method for FP8.
Supports loading FP8 checkpoints with static weight scale and
dynamic/static activation scale.
Also supports loading quantized FP16/BF16 model checkpoints with dynamic
activation scaling. The weight scaling factor will be initialized after
the model weights are loaded.
Args:
quant_config: The quantization config.
"""
def __init__(self, quant_config: Fp8Config):
self.quant_config = quant_config
def create_weights(
self,
layer: Module,
num_experts: int,
hidden_size: int,
intermediate_size: int,
params_dtype: torch.dtype,
**extra_weight_attrs,
):
if self.quant_config.is_checkpoint_fp8_serialized:
params_dtype = torch.float8_e4m3fn
# WEIGHTS
w13_weight = torch.nn.Parameter(
torch.empty(
num_experts, 2 * intermediate_size, hidden_size, dtype=params_dtype
),
requires_grad=False,
)
layer.register_parameter("w13_weight", w13_weight)
set_weight_attrs(w13_weight, extra_weight_attrs)
w2_weight = torch.nn.Parameter(
torch.empty(
num_experts, hidden_size, intermediate_size, dtype=params_dtype
),
requires_grad=False,
)
layer.register_parameter("w2_weight", w2_weight)
set_weight_attrs(w2_weight, extra_weight_attrs)
# WEIGHT_SCALES
# Allocate 2 scales for w1 and w3 respectively.
# They will be combined to a single scale after weight loading.
w13_scale = torch.nn.Parameter(
torch.ones(num_experts, 2, dtype=torch.float32), requires_grad=False
)
layer.register_parameter("w13_scale", w13_scale)
w2_scale = torch.nn.Parameter(
torch.ones(num_experts, dtype=torch.float32), requires_grad=False
)
layer.register_parameter("w2_scale", w2_scale)
# If loading fp8 checkpoint, pass the weight loaders.
# If loading an fp16 checkpoint, do not (we will quantize in
# process_weights_after_loading()
if self.quant_config.is_checkpoint_fp8_serialized:
set_weight_attrs(w13_scale, extra_weight_attrs)
set_weight_attrs(w2_scale, extra_weight_attrs)
# INPUT_SCALES
if self.quant_config.activation_scheme == "static":
if not self.quant_config.is_checkpoint_fp8_serialized:
raise ValueError(
"Found static activation scheme for checkpoint that "
"was not serialized fp8."
)
a13_scale = torch.nn.Parameter(
torch.ones(num_experts, dtype=torch.float32), requires_grad=False
)
layer.register_parameter("a13_scale", a13_scale)
set_weight_attrs(a13_scale, extra_weight_attrs)
a2_scale = torch.nn.Parameter(
torch.ones(num_experts, dtype=torch.float32), requires_grad=False
)
layer.register_parameter("a2_scale", a2_scale)
set_weight_attrs(a2_scale, extra_weight_attrs)
else:
layer.a13_scale = None
layer.a2_scale = None
def process_weights_after_loading(self, layer: Module) -> None:
# If checkpoint is fp16 or bfloat16, quantize in place.
if not self.quant_config.is_checkpoint_fp8_serialized:
# If ROCm, use float8_e4m3fnuz instead (MI300x HW)
fp8_dtype = torch.float8_e4m3fnuz if is_hip() else torch.float8_e4m3fn
w13_weight = torch.empty_like(layer.w13_weight.data, dtype=fp8_dtype)
w2_weight = torch.empty_like(layer.w2_weight.data, dtype=fp8_dtype)
# Re-initialize w13_scale because we directly quantize
# merged w13 weights and generate a single scaling factor.
layer.w13_scale = torch.nn.Parameter(
torch.ones(
layer.num_experts, dtype=torch.float32, device=w13_weight.device
),
requires_grad=False,
)
for expert in range(layer.num_experts):
w13_weight[expert, :, :], layer.w13_scale[expert] = (
ops.scaled_fp8_quant(layer.w13_weight.data[expert, :, :])
)
w2_weight[expert, :, :], layer.w2_scale[expert] = ops.scaled_fp8_quant(
layer.w2_weight.data[expert, :, :]
)
layer.w13_weight = torch.nn.Parameter(w13_weight, requires_grad=False)
layer.w2_weight = torch.nn.Parameter(w2_weight, requires_grad=False)
# If ROCm, apply weight padding (min. Mem channel contention) only if set
if is_hip() and bool(int(os.getenv("MOE_PADDING", "0"))):
layer.w13_weight = torch.nn.Parameter(
F.pad(layer.w13_weight.data, (0, padding_size), "constant", 0),
requires_grad=False,
)
torch.cuda.empty_cache()
layer.w2_weight = torch.nn.Parameter(
F.pad(layer.w2_weight.data, (0, padding_size), "constant", 0),
requires_grad=False,
)
torch.cuda.empty_cache()
return
# If checkpoint is fp8, we need to handle that the
# MoE kernels require single activation scale and single weight
# scale for w13 per expert.
else:
# Fp8 moe kernels require a single activation scale.
# We take the max of all the scales in case they differ.
if self.quant_config.activation_scheme == "static":
if layer.a13_scale is None or layer.a2_scale is None:
raise ValueError(
"QuantConfig has static quantization, but found "
"activation scales are None."
)
if not all_close_1d(layer.a13_scale) or not all_close_1d(
layer.a2_scale
):
print_warning_once(
"Found input_scales that are not equal for "
"fp8 MoE layer. Using the maximum across experts "
"for each layer. "
)
layer.a13_scale = torch.nn.Parameter(
layer.a13_scale.max(), requires_grad=False
)
layer.a2_scale = torch.nn.Parameter(
layer.a2_scale.max(), requires_grad=False
)
# If ROCm, normalize the weights and scales to e4m3fnuz
if is_hip():
# Normalize the weights and scales
w13_weight, w13_scale, a13_scale = normalize_e4m3fn_to_e4m3fnuz(
layer.w13_weight, layer.w13_scale, layer.a13_scale
)
w2_weight, w2_scale, a2_scale = normalize_e4m3fn_to_e4m3fnuz(
layer.w2_weight, layer.w2_scale, layer.a2_scale
)
# Reset the parameters
layer.w13_weight = torch.nn.Parameter(w13_weight, requires_grad=False)
layer.w13_scale = torch.nn.Parameter(w13_scale, requires_grad=False)
if a13_scale is not None:
layer.a13_scale = torch.nn.Parameter(a13_scale, requires_grad=False)
layer.w2_weight = torch.nn.Parameter(w2_weight, requires_grad=False)
layer.w2_scale = torch.nn.Parameter(w2_scale, requires_grad=False)
if a2_scale is not None:
layer.a2_scale = torch.nn.Parameter(a2_scale, requires_grad=False)
# Fp8 moe kernel needs single weight scale for w13 per expert.
# We take the max then dequant and requant each expert.
assert layer.w13_scale is not None
shard_size = layer.intermediate_size_per_partition
max_w13_scales = layer.w13_scale.max(dim=1).values
for expert_id in range(layer.num_experts):
start = 0
for shard_id in range(2):
dq_weight = per_tensor_dequantize(
layer.w13_weight[expert_id][start : start + shard_size, :],
layer.w13_scale[expert_id][shard_id],
)
layer.w13_weight[expert_id][start : start + shard_size, :], _ = (
ops.scaled_fp8_quant(dq_weight, max_w13_scales[expert_id])
)
start += shard_size
layer.w13_scale = torch.nn.Parameter(max_w13_scales, requires_grad=False)
# If ROCm, apply weight padding (min. Mem channel contention) only if set
if is_hip() and bool(int(os.getenv("MOE_PADDING", "0"))):
layer.w13_weight = torch.nn.Parameter(
F.pad(layer.w13_weight.data, (0, padding_size), "constant", 0),
requires_grad=False,
)
torch.cuda.empty_cache()
layer.w2_weight = torch.nn.Parameter(
F.pad(layer.w2_weight.data, (0, padding_size), "constant", 0),
requires_grad=False,
)
torch.cuda.empty_cache()
return
def apply(
self,
layer: torch.nn.Module,
x: torch.Tensor,
router_logits: torch.Tensor,
top_k: int,
renormalize: bool = True,
use_grouped_topk: bool = False,
num_expert_group: Optional[int] = None,
topk_group: Optional[int] = None,
) -> torch.Tensor:
from sglang.srt.layers.fused_moe.fused_moe import fused_moe
return fused_moe(
x,
layer.w13_weight,
layer.w2_weight,
router_logits,
top_k,
renormalize=renormalize,
inplace=True,
use_fp8=True,
w1_scale=layer.w13_scale,
w2_scale=layer.w2_scale,
a1_scale=layer.a13_scale,
a2_scale=layer.a2_scale,
use_grouped_topk=use_grouped_topk,
num_expert_group=num_expert_group,
topk_group=topk_group,
)