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ColossalAI/extensions/flash_attention/flash_attention_sdpa_cuda.py

57 lines
1.8 KiB

from ..base_extension import _Extension
class FlashAttentionSdpaCudaExtension(_Extension):
def __init__(self):
super().__init__(name="flash_attention_sdpa_cuda", support_aot=False, support_jit=False)
def is_available(self) -> bool:
# cuda extension can only be built if cuda is available
try:
import torch
cuda_available = torch.cuda.is_available()
except:
cuda_available = False
return cuda_available
def assert_compatible(self) -> bool:
pass
def build_aot(self) -> None:
raise NotImplementedError("Flash attention SDPA does not require ahead-of-time compilation.")
def build_jit(self) -> None:
raise NotImplementedError("Flash attention SDPA does not require just-in-time compilation.")
def load(self):
from typing import Optional
import torch
def flash_attention(
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
dropout_p: float = 0.0,
scale: Optional[float] = None,
attention_mask: Optional[torch.Tensor] = None,
is_causal: bool = False,
cu_seqlens_q: Optional[torch.Tensor] = None,
cu_seqlens_kv: Optional[torch.Tensor] = None,
max_seqlen_q: Optional[int] = None,
max_seqlen_kv: Optional[int] = None,
q_indices: Optional[torch.Tensor] = None,
kv_indices: Optional[torch.Tensor] = None,
):
return torch.nn.functional.scaled_dot_product_attention(
q,
k,
v,
attn_mask=attention_mask,
dropout_p=dropout_p,
scale=scale,
)
return flash_attention