Feature(MInference): add triton-based decoding in case flash_attn is …

…not available (#35)

* add triton-based decoding in case flash_attn is not available
* Feature(MInference): remove flash_attn dependency

Co-authored-by: Huiqiang Jiang <hjiang@microsoft.com>

README.md

@@ -38,7 +38,7 @@ _Now, you can process **1M context 10x faster in a single A100** using Long-cont
 ### Requirements
 
 - Torch
-- FlashAttention-2
+- FlashAttention-2 (Optional)
 - Triton == 2.1.0
 
 To get started with MInference, simply install it using pip:

minference/modules/inf_llm.py

@@ -6,9 +6,15 @@
 from typing import Optional, Tuple
 
 import torch
-from flash_attn import flash_attn_func
 from transformers.modeling_outputs import CausalLMOutput
 
+try:
+    from flash_attn import flash_attn_func as dense_decoding_func
+except ImportError:
+    from ..ops.flash_attn_triton import (
+        _flash_attn_triton_decoding as dense_decoding_func,
+    )
+
 from ..ops.streaming_kernel import TritonMultiStageDotProductionAttention
 
 
@@ -1084,7 +1090,7 @@ def forward(
             h_v = h_v.transpose(1, 2)
 
             # (batch_size, seqlen, nheads, headdim)
-            o = flash_attn_func(h_q, h_k, h_v, causal=True)
+            o = dense_decoding_func(h_q, h_k, h_v)
 
             o = o.reshape(batch_size, len_q, dim_head * num_heads)
             o = attention_out(o)

minference/modules/minference_forward.py

@@ -12,15 +12,20 @@
 
 if _is_package_available("vllm"):
     try:
-        from vllm.attention.backends.flash_attn import *
+        from vllm.attention.ops.paged_attn import PagedAttention
     except:
-        warnings.warn("Only support 'vllm==0.4.1'. Please update your vllm version.")
+        warnings.warn("Only support 'vllm>=0.4.0'. Please update your vllm version.")
 
 from ..ops.block_sparse_flash_attention import block_sparse_attention
 from ..ops.pit_sparse_flash_attention_v2 import vertical_slash_sparse_attention
 from ..ops.streaming_kernel import streaming_forward, streaming_forward2
 from .snap_kv import *
 
+try:
+    from flash_attn import flash_attn_func
+except ImportError:
+    from ..ops.flash_attn_triton import _flash_attn_triton_decoding as flash_attn_func
+
 last_q = 64
 arange = torch.arange(last_q, device="cuda")
 LAST_Q_MASK = arange[None, None, :, None] >= arange[None, None, None, :]
@@ -1113,7 +1118,7 @@ def forward_vllm_043(
         key: torch.Tensor,
         value: torch.Tensor,
         kv_cache: torch.Tensor,
-        attn_metadata: FlashAttentionMetadata,
+        attn_metadata,
         kv_scale: float,
         layer_idx: int,
     ) -> torch.Tensor:

minference/ops/block_sparse_flash_attention.py

@@ -5,8 +5,8 @@
 import torch
 import triton
 import triton.language as tl
-from flash_attn import flash_attn_varlen_func
 
+# from flash_attn import flash_attn_varlen_func
 # import pycuda.autoprimaryctx
 # from pycuda.compiler import SourceModule