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2026-07-13 13:18:33 +08:00

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Python

# Copyright (c) Microsoft Corporation.
# SPDX-License-Identifier: Apache-2.0
# DeepSpeed Team
import torch
import torch.nn.functional as F
from ..config import DeepSpeedInferenceConfig
from .base import BaseOp
from deepspeed.ops.transformer.inference.op_binding.workspace import InferenceContext
class SoftmaxOp(BaseOp):
def __init__(self, config: DeepSpeedInferenceConfig):
super(SoftmaxOp, self).__init__(config)
self.num_attention_heads_per_partition = config.heads // config.mp_size
try:
if self.config.dtype in [torch.float16, torch.int8]:
self.softmax_func = self.inference_module.softmax_fp16
elif self.config.dtype == torch.bfloat16:
self.softmax_func = self.inference_module.softmax_bf16
else:
self.softmax_func = self.inference_module.softmax_fp32
except AttributeError:
self.softmax_func = self.softmax_fallback
@staticmethod
def softmax_fallback(attn_scores, attn_mask, alibi, triangular, recompute, local_attention, window_size, async_op,
layer_scale, head_offset, mp_size):
scores_len = len(attn_scores.size())
heads = 1
if scores_len > 1:
heads = attn_scores.size()[1]
num_attention_heads_per_partition = heads // mp_size
if alibi is not None:
if len(alibi.shape) == 1:
alibi = None
else:
alibi = alibi[head_offset:head_offset + num_attention_heads_per_partition]
if attn_mask is not None and len(attn_mask.shape) == 1:
attn_mask = None
input_dtype = attn_scores.dtype
attn_scores *= layer_scale
if alibi is not None:
attn_scores += alibi
if attn_mask is not None:
# expand atten_mask from two dim into 4 dim, insert two dims in the middle
if len(attn_mask.shape) == 2:
attn_mask = attn_mask[:, None, None, :]
attn_scores += attn_mask
if triangular:
if attn_scores.shape[2] == 1: # query using kv cache
token_idx = InferenceContext.Instance().current_tokens()
tri = torch.arange(attn_scores.shape[2], device=attn_scores.device).ge(token_idx)
else:
tri = ~torch.tril(torch.ones(attn_scores.size(), device=attn_scores.device)).to(bool)
attn_scores = torch.masked_fill(attn_scores, tri, float('-inf'))
output = F.softmax(attn_scores, dim=-1, dtype=torch.float32).to(input_dtype)
return output
def forward(self, attn_scores: torch.Tensor, attn_mask: torch.Tensor, alibi: torch.Tensor, triangular: bool,
recompute: bool, local_attention: bool, window_size: int, async_op: bool, layer_scale: float,
head_offset: int):
output = self.softmax_func(attn_scores, attn_mask, alibi, triangular, recompute, local_attention, window_size,
async_op, layer_scale, head_offset, self.config.mp_size)
return output