96b6f475dd
Co-authored-by: Jiang Li <jiang1.li@intel.com> Co-authored-by: Kunshang Ji <kunshang.ji@intel.com>
140 lines
4.7 KiB
Python
140 lines
4.7 KiB
Python
"""Custom activation functions."""
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import math
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from typing import Optional
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import torch
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import torch.nn as nn
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import torch.nn.functional as F
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from vllm._C import ops
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from vllm.model_executor.layers.quantization import QuantizationConfig
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from vllm.model_executor.parallel_utils.parallel_state import (
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get_tensor_model_parallel_rank, get_tensor_model_parallel_world_size)
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from vllm.model_executor.parallel_utils.utils import divide
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from vllm.model_executor.utils import set_weight_attrs
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class SiluAndMul(nn.Module):
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"""An activation function for SwiGLU.
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The function computes x -> silu(x[:d]) * x[d:] where d = x.shape[-1] // 2.
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Shapes:
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x: (batch_size, seq_len, 2 * d) or (num_tokens, 2 * d)
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return: (batch_size, seq_len, d) or (num_tokens, d)
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"""
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def _forward(self, x: torch.Tensor) -> torch.Tensor:
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"""PyTorch-native implementation equivalent to forward()."""
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d = x.shape[-1] // 2
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return F.silu(x[..., :d]) * x[..., d:]
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def forward(self, x: torch.Tensor) -> torch.Tensor:
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d = x.shape[-1] // 2
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output_shape = (x.shape[:-1] + (d, ))
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out = torch.empty(output_shape, dtype=x.dtype, device=x.device)
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ops.silu_and_mul(out, x)
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return out
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class NewGELU(nn.Module):
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def _forward(self, x: torch.Tensor) -> torch.Tensor:
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"""PyTorch-native implementation equivalent to forward()."""
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c = math.sqrt(2.0 / math.pi)
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return 0.5 * x * (1.0 + torch.tanh(c *
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(x + 0.044715 * torch.pow(x, 3.0))))
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def forward(self, x: torch.Tensor) -> torch.Tensor:
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out = torch.empty_like(x)
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ops.gelu_new(out, x)
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return out
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class FastGELU(nn.Module):
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def _forward(self, x: torch.Tensor) -> torch.Tensor:
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"""PyTorch-native implementation equivalent to forward()."""
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return 0.5 * x * (1.0 + torch.tanh(x * 0.7978845608 *
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(1.0 + 0.044715 * x * x)))
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def forward(self, x: torch.Tensor) -> torch.Tensor:
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out = torch.empty_like(x)
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ops.gelu_fast(out, x)
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return out
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class ScaledActivation(nn.Module):
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"""An activation function with post-scale parameters.
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This is used for some quantization methods like AWQ.
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"""
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def __init__(
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self,
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act_module: nn.Module,
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intermediate_size: int,
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input_is_parallel: bool = True,
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params_dtype: Optional[torch.dtype] = None,
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):
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super().__init__()
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self.act = act_module
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self.input_is_parallel = input_is_parallel
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if input_is_parallel:
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tp_size = get_tensor_model_parallel_world_size()
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intermediate_size_per_partition = divide(intermediate_size,
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tp_size)
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else:
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intermediate_size_per_partition = intermediate_size
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if params_dtype is None:
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params_dtype = torch.get_default_dtype()
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self.scales = nn.Parameter(
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torch.empty(intermediate_size_per_partition, dtype=params_dtype))
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set_weight_attrs(self.scales, {"weight_loader": self.weight_loader})
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def forward(self, x: torch.Tensor) -> torch.Tensor:
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return self.act(x) / self.scales
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def weight_loader(self, param: nn.Parameter, loaded_weight: torch.Tensor):
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param_data = param.data
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if self.input_is_parallel:
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tp_rank = get_tensor_model_parallel_rank()
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shard_size = param_data.shape[0]
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start_idx = tp_rank * shard_size
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loaded_weight = loaded_weight.narrow(0, start_idx, shard_size)
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assert param_data.shape == loaded_weight.shape
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param_data.copy_(loaded_weight)
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_ACTIVATION_REGISTRY = {
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"gelu": nn.GELU(),
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"gelu_fast": FastGELU(),
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"gelu_new": NewGELU(),
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"gelu_pytorch_tanh": nn.GELU(approximate="tanh"),
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"relu": nn.ReLU(),
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}
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def get_act_fn(
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act_fn_name: str,
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quant_config: Optional[QuantizationConfig] = None,
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intermediate_size: Optional[int] = None,
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input_is_parallel: bool = True,
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params_dtype: Optional[torch.dtype] = None,
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) -> nn.Module:
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"""Get an activation function by name."""
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act_fn_name = act_fn_name.lower()
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if act_fn_name not in _ACTIVATION_REGISTRY:
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raise ValueError(
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f"Activation function {act_fn_name!r} is not supported.")
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act_fn = _ACTIVATION_REGISTRY[act_fn_name]
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if (quant_config is not None
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and act_fn_name in quant_config.get_scaled_act_names()):
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if intermediate_size is None:
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raise ValueError("intermediate_size must be specified for scaled "
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"activation functions.")
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return ScaledActivation(act_fn, intermediate_size, input_is_parallel,
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params_dtype)
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return act_fn
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