[transformer] support flash att by 'torch scaled dot attention'

requirements.txt

@@ -13,8 +13,8 @@ flake8-pyi==20.5.0
 mccabe
 pycodestyle==2.6.0
 pyflakes==2.2.0
-torch==2.1.2
-torchaudio==2.1.2
+torch>=2.1.2
+torchaudio>=2.1.2
 tqdm
 deepspeed<0.13.0
 librosa

test/wenet/transformer/test_attention.py

@@ -0,0 +1,111 @@
+import torch
+import pytest
+from wenet.transformer.attention import MultiHeadedAttention
+from wenet.transformer.encoder_layer import TransformerEncoderLayer
+from wenet.transformer.positionwise_feed_forward import PositionwiseFeedForward
+from wenet.utils.class_utils import WENET_ACTIVATION_CLASSES
+
+from wenet.utils.mask import add_optional_chunk_mask, make_non_pad_mask
+
+
+@pytest.mark.parametrize("args", [
+    {
+        "n_feat": 256,
+        "n_head": 4,
+        "dropout_rate": 0.0
+    },
+    {
+        "n_feat": 512,
+        "n_head": 8,
+        "dropout_rate": 0.0
+    },
+    {
+        "n_feat": 1280,
+        "n_head": 20,
+        "dropout_rate": 0.0
+    },
+    {
+        "n_feat": 512,
+        "n_head": 4,
+        "dropout_rate": 0.0
+    },
+])
+def test_sdpa(args):
+    torch.manual_seed(777)
+    mha_module = MultiHeadedAttention(use_sdpa=False, **args)
+    torch.manual_seed(777)
+    mha_module_with_sdpa = MultiHeadedAttention(use_sdpa=True, **args)
+    mha_module.eval()
+    mha_module_with_sdpa.eval()
+
+    q = torch.rand(10, 100, args['n_feat'])
+    k = torch.rand(10, 100, args['n_feat'])
+    v = torch.rand(10, 100, args['n_feat'])
+    input_lens = torch.tensor([100, 90, 80, 79, 60, 51, 40, 30, 10, 5])
+    mask = make_non_pad_mask(input_lens).unsqueeze(1)
+    att_mask = add_optional_chunk_mask(q,
+                                       mask,
+                                       use_dynamic_chunk=True,
+                                       decoding_chunk_size=0,
+                                       static_chunk_size=0,
+                                       use_dynamic_left_chunk=True,
+                                       num_decoding_left_chunks=-1)
+    output, cache = mha_module(q, k, v, mask=att_mask)
+
+    att_mask_bias = (1.0 - att_mask.float()) * torch.finfo(torch.float).min
+    output_with_sdpa, cache_with_sdpa = mha_module_with_sdpa(
+        q, k, v, mask=att_mask_bias)
+    assert torch.allclose(
+        output * mask.transpose(1, 2),
+        output_with_sdpa * mask.transpose(1, 2),
+        atol=9e-7,
+    )
+    assert torch.allclose(cache, cache_with_sdpa)
+
+    n_blocks = 12
+    torch.manual_seed(777)
+    mha_layers = [
+        TransformerEncoderLayer(
+            args['n_feat'],
+            MultiHeadedAttention(use_sdpa=False, **args),
+            PositionwiseFeedForward(
+                args['n_feat'],
+                2048,
+                0.0,
+                WENET_ACTIVATION_CLASSES['swish'](),
+            ),
+            0.0,
+            normalize_before=True,
+        ) for _ in range(n_blocks)
+    ]
+
+    torch.manual_seed(777)
+    mha_layers_with_sdpa = [
+        TransformerEncoderLayer(
+            args['n_feat'],
+            MultiHeadedAttention(use_sdpa=True, **args),
+            PositionwiseFeedForward(
+                args['n_feat'],
+                2048,
+                0.0,
+                WENET_ACTIVATION_CLASSES['swish'](),
+            ),
+            0.0,
+            normalize_before=True,
+        ) for _ in range(n_blocks)
+    ]
+
+    for i in range(n_blocks):
+        output, _, cache, _ = mha_layers[i](q, att_mask, None, mask)
+        output_with_sdpa, _, cache_with_sdpa, _ = mha_layers_with_sdpa[i](
+            q, att_mask_bias, None, mask)
+
+        assert torch.allclose(
+            output * mask.transpose(1, 2),
+            output_with_sdpa * mask.transpose(1, 2),
+            atol=9e-7,
+            rtol=9e-4,
+        )
+        # assert torch.allclose(cache, cache_with_sdpa)
+
+        q = output

wenet/transformer/attention.py

@@ -36,7 +36,8 @@ def __init__(self,
                  n_head: int,
                  n_feat: int,
                  dropout_rate: float,
-                 key_bias: bool = True):
+                 key_bias: bool = True,
+                 use_sdpa: bool = False):
         """Construct an MultiHeadedAttention object."""
         super().__init__()
         assert n_feat % n_head == 0
@@ -49,6 +50,9 @@ def __init__(self,
         self.linear_out = nn.Linear(n_feat, n_feat)
         self.dropout = nn.Dropout(p=dropout_rate)
 
+        self.use_sdpa = use_sdpa
+        self.dropout_rate = dropout_rate
+
     def forward_qkv(
         self, query: torch.Tensor, key: torch.Tensor, value: torch.Tensor
     ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
@@ -192,8 +196,22 @@ def forward(
         #   non-trivial to calculate `next_cache_start` here.
         new_cache = torch.cat((k, v), dim=-1)
 
-        scores = torch.matmul(q, k.transpose(-2, -1)) / math.sqrt(self.d_k)
-        return self.forward_attention(v, scores, mask), new_cache
+        if not self.use_sdpa:
+            scores = torch.matmul(q, k.transpose(-2, -1)) / math.sqrt(self.d_k)
+            return self.forward_attention(v, scores, mask), new_cache
+        else:
+            output = torch.nn.functional.scaled_dot_product_attention(
+                q,
+                k,
+                v,
+                attn_mask=mask.unsqueeze(1),
+                dropout_p=self.dropout_rate,
+                scale=1 / math.sqrt(self.d_k),
+            )
+            output = (output.transpose(1, 2).contiguous().view(
+                query.size(0), -1,
+                self.h * self.d_k))  # (batch, time1, d_model)
+            return self.linear_out(output), new_cache
 
 
 class RelPositionMultiHeadedAttention(MultiHeadedAttention):

wenet/transformer/decoder.py

@@ -26,6 +26,7 @@
     WENET_ATTENTION_CLASSES,
     WENET_ACTIVATION_CLASSES,
 )
+from wenet.utils.common import mask_to_bias
 from wenet.utils.mask import (subsequent_mask, make_pad_mask)
 
 
@@ -73,6 +74,7 @@ def __init__(
         activation_type: str = "relu",
         gradient_checkpointing: bool = False,
         tie_word_embedding: bool = False,
+        use_sdpa: bool = False,
     ):
         super().__init__()
         attention_dim = encoder_output_size
@@ -98,10 +100,10 @@ def __init__(
                 attention_dim,
                 WENET_ATTENTION_CLASSES["selfattn"](
                     attention_heads, attention_dim,
-                    self_attention_dropout_rate, key_bias),
+                    self_attention_dropout_rate, key_bias, use_sdpa),
                 WENET_ATTENTION_CLASSES["selfattn"](
                     attention_heads, attention_dim, src_attention_dropout_rate,
-                    key_bias) if src_attention else None,
+                    key_bias, use_sdpa) if src_attention else None,
                 PositionwiseFeedForward(attention_dim, linear_units,
                                         dropout_rate, activation),
                 dropout_rate,
@@ -111,6 +113,7 @@ def __init__(
 
         self.gradient_checkpointing = gradient_checkpointing
         self.tie_word_embedding = tie_word_embedding
+        self.use_sdpa = use_sdpa
 
     def forward(
         self,
@@ -152,6 +155,10 @@ def forward(
                             device=tgt_mask.device).unsqueeze(0)
         # tgt_mask: (B, L, L)
         tgt_mask = tgt_mask & m
+        if self.use_sdpa:
+            tgt_mask = mask_to_bias(tgt_mask, tgt.dtype)
+            memory_mask = mask_to_bias(memory_mask, memory_mask.dtype)
+
         x, _ = self.embed(tgt)
         if self.gradient_checkpointing and self.training:
             x = self.forward_layers_checkpointed(x, tgt_mask, memory,
@@ -290,6 +297,7 @@ def __init__(
         key_bias: bool = True,
         gradient_checkpointing: bool = False,
         tie_word_embedding: bool = False,
+        use_sdpa: bool = False,
     ):
 
         super().__init__()
@@ -309,7 +317,8 @@ def __init__(
             normalize_before,
             key_bias=key_bias,
             gradient_checkpointing=gradient_checkpointing,
-            tie_word_embedding=tie_word_embedding)
+            tie_word_embedding=tie_word_embedding,
+            use_sdpa=use_sdpa)
 
         self.right_decoder = TransformerDecoder(
             vocab_size,
@@ -326,7 +335,8 @@ def __init__(
             normalize_before,
             key_bias=key_bias,
             gradient_checkpointing=gradient_checkpointing,
-            tie_word_embedding=tie_word_embedding)
+            tie_word_embedding=tie_word_embedding,
+            use_sdpa=use_sdpa)
 
     def forward(
         self,

wenet/transformer/encoder.py

@@ -31,6 +31,7 @@
 )
 from wenet.utils.mask import make_pad_mask
 from wenet.utils.mask import add_optional_chunk_mask
+from wenet.utils.common import mask_to_bias
 
 
 class BaseEncoder(torch.nn.Module):
@@ -53,6 +54,7 @@ def __init__(
         global_cmvn: torch.nn.Module = None,
         use_dynamic_left_chunk: bool = False,
         gradient_checkpointing: bool = False,
+        use_sdpa: bool = False,
     ):
         """
         Args:
@@ -84,6 +86,7 @@ def __init__(
             key_bias: whether use bias in attention.linear_k, False for whisper models.
             gradient_checkpointing: rerunning a forward-pass segment for each
                 checkpointed segment during backward.
+            use_sdpa: whether to use SDPA, currently only support transformer for now
         """
         super().__init__()
         self._output_size = output_size
@@ -103,6 +106,7 @@ def __init__(
         self.use_dynamic_chunk = use_dynamic_chunk
         self.use_dynamic_left_chunk = use_dynamic_left_chunk
         self.gradient_checkpointing = gradient_checkpointing
+        self.use_sdpa = use_sdpa
 
     def output_size(self) -> int:
         return self._output_size
@@ -149,6 +153,8 @@ def forward(
                                               decoding_chunk_size,
                                               self.static_chunk_size,
                                               num_decoding_left_chunks)
+        if self.use_sdpa:
+            chunk_masks = mask_to_bias(chunk_masks, xs.dtype)
         if self.gradient_checkpointing and self.training:
             xs = self.forward_layers_checkpointed(xs, chunk_masks, pos_emb,
                                                   mask_pad)
@@ -355,6 +361,7 @@ def __init__(
         key_bias: bool = True,
         activation_type: str = "relu",
         gradient_checkpointing: bool = False,
+        use_sdpa: bool = False,
     ):
         """ Construct TransformerEncoder
 
@@ -365,15 +372,16 @@ def __init__(
                          positional_dropout_rate, attention_dropout_rate,
                          input_layer, pos_enc_layer_type, normalize_before,
                          static_chunk_size, use_dynamic_chunk, global_cmvn,
-                         use_dynamic_left_chunk, gradient_checkpointing)
+                         use_dynamic_left_chunk, gradient_checkpointing,
+                         use_sdpa)
         activation = WENET_ACTIVATION_CLASSES[activation_type]()
         self.encoders = torch.nn.ModuleList([
             TransformerEncoderLayer(
                 output_size,
                 WENET_ATTENTION_CLASSES["selfattn"](attention_heads,
                                                     output_size,
                                                     attention_dropout_rate,
-                                                    key_bias),
+                                                    key_bias, use_sdpa),
                 PositionwiseFeedForward(output_size, linear_units,
                                         dropout_rate, activation),
                 dropout_rate, normalize_before) for _ in range(num_blocks)
@@ -433,7 +441,7 @@ def __init__(
                          positional_dropout_rate, attention_dropout_rate,
                          input_layer, pos_enc_layer_type, normalize_before,
                          static_chunk_size, use_dynamic_chunk, global_cmvn,
-                         use_dynamic_left_chunk, gradient_checkpointing)
+                         use_dynamic_left_chunk, gradient_checkpointing, False)
         activation = WENET_ACTIVATION_CLASSES[activation_type]()
 
         # self-attention module definition

wenet/transformer/search.py

@@ -19,7 +19,8 @@
 import torch
 from torch.nn.utils.rnn import pad_sequence
 
-from wenet.utils.common import (add_sos_eos, log_add, add_whisper_tokens)
+from wenet.utils.common import (add_sos_eos, log_add, add_whisper_tokens,
+                                mask_to_bias)
 from wenet.utils.ctc_utils import remove_duplicates_and_blank
 from wenet.utils.mask import (make_pad_mask, mask_finished_preds,
                               mask_finished_scores, subsequent_mask)
@@ -289,6 +290,8 @@ def attention_beam_search(
                                        ]).unsqueeze(1).to(device)  # (B*N, 1)
     end_flag = torch.zeros_like(scores, dtype=torch.bool, device=device)
     cache: Optional[List[torch.Tensor]] = None
+    if model.decoder.use_sdpa:
+        encoder_mask = mask_to_bias(encoder_mask, encoder_out.dtype)
     # 2. Decoder forward step by step
     for i in range(prefix_len, maxlen + 1):
         # Stop if all batch and all beam produce eos
@@ -297,6 +300,8 @@ def attention_beam_search(
         # 2.1 Forward decoder step
         hyps_mask = subsequent_mask(i).unsqueeze(0).repeat(
             running_size, 1, 1).to(device)  # (B*N, i, i)
+        if model.decoder.use_sdpa:
+            hyps_mask = mask_to_bias(hyps_mask, encoder_out.dtype)
         # logp: (B*N, vocab)
         logp, cache = model.decoder.forward_one_step(encoder_out, encoder_mask,
                                                      hyps, hyps_mask, cache)