[FIXBUG ] Allow disabling rocm_aiter_fa backend for ROCm GPUs not compatible with AITER

vllm/v1/spec_decode/eagle.py

@@ -2,7 +2,8 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 import ast
 from dataclasses import replace
-from typing import Optional
+from importlib.util import find_spec
+from typing import Optional, Protocol
 
 import numpy as np
 import torch
@@ -20,8 +21,6 @@
 from vllm.platforms import current_platform
 from vllm.utils import is_pin_memory_available
 from vllm.v1.attention.backends.flash_attn import FlashAttentionMetadata
-from vllm.v1.attention.backends.rocm_aiter_fa import (
-    AiterFlashAttentionMetadata)
 from vllm.v1.attention.backends.tree_attn import (TreeAttentionMetadata,
                                                   TreeAttentionMetadataBuilder)
 from vllm.v1.attention.backends.triton_attn import TritonAttentionMetadata
@@ -34,6 +33,17 @@
 PADDING_SLOT_ID = -1
 
 
+class EagleAttentionMetadata(Protocol):
+    # Required attributes
+    num_actual_tokens: int
+    max_query_len: int
+    query_start_loc: torch.Tensor
+    max_seq_len: int
+    seq_lens: torch.Tensor
+    block_table: torch.Tensor
+    slot_mapping: torch.Tensor
+
+
 class EagleProposer:
 
     def __init__(
@@ -97,6 +107,20 @@ def __init__(
             dtype=self.dtype,
             device=device)
 
+        # Determine allowed attention backends once during initialization.
+        self.allowed_attn_types: tuple[type[EagleAttentionMetadata], ...]
+        if current_platform.is_rocm():
+            rocm_types = [TritonAttentionMetadata, FlashAttentionMetadata]
+            # vllm.v1.attention.backends.rocm_aiter_fa is an optional backend
+            if find_spec("vllm.v1.attention.backends.rocm_aiter_fa"):
+                from vllm.v1.attention.backends.rocm_aiter_fa import (
+                    AiterFlashAttentionMetadata)
+                rocm_types.append(AiterFlashAttentionMetadata)
+            self.allowed_attn_types = tuple(rocm_types)
+        else:
+            self.allowed_attn_types = (FlashAttentionMetadata,
+                                       TreeAttentionMetadata)
+
         # Parse the speculative token tree.
         spec_token_tree = self.speculative_config.speculative_token_tree
         self.tree_choices: list[tuple[int,
@@ -165,7 +189,7 @@ def propose(
         for layer_name in self.attn_layer_names:
             per_layer_attn_metadata[layer_name] = attn_metadata
         if self.use_cuda_graph and \
-            num_tokens <= self.cudagraph_batch_sizes[-1]:
+                num_tokens <= self.cudagraph_batch_sizes[-1]:
             num_input_tokens = self.vllm_config.pad_for_cudagraph(num_tokens)
         else:
             num_input_tokens = num_tokens
@@ -225,25 +249,13 @@ def propose(
         # TODO: Currently, MTP module released by deepseek only has
         # one layer. Adapt this code to support multiple layers once
         # there's a multi-layer MTP module.
-
-        # On ROCm, both AiterFlashAttention and TritonAttention
-        # support multi-token eagle spec decode.
-        if current_platform.is_rocm():
-            assert isinstance(
-                attn_metadata,
-                (TritonAttentionMetadata, AiterFlashAttentionMetadata,
-                 FlashAttentionMetadata))
-        else:
-            # Currently, only FlashAttention supports multi-token eagle spec
-            # decode. This is because the code below makes assumptions about
-            # attn_metadata attributes available.
-            assert isinstance(attn_metadata, FlashAttentionMetadata)
+        assert isinstance(attn_metadata, self.allowed_attn_types)
 
         # Generate the remaining draft tokens.
         draft_token_ids_list = [draft_token_ids]
 
         if self.use_cuda_graph and \
-            batch_size <= self.cudagraph_batch_sizes[-1]:
+                batch_size <= self.cudagraph_batch_sizes[-1]:
             input_batch_size = self.vllm_config.pad_for_cudagraph(batch_size)
         else:
             input_batch_size = batch_size
@@ -449,7 +461,7 @@ def propose_tree(
                 num_tokens, -1)
 
             if self.use_cuda_graph and \
-                num_tokens <= self.cudagraph_batch_sizes[-1]:
+                    num_tokens <= self.cudagraph_batch_sizes[-1]:
                 num_input_tokens = self.vllm_config.pad_for_cudagraph(
                     num_tokens)
             else:
@@ -508,19 +520,19 @@ def prepare_inputs(
         """
         # E.g.
         #  common_attn_metadata.query_start_loc{_cpu}:
-        #         [0, q1, q1 + q2, q1 + q2 + q3]
+        #       [0, q1, q1 + q2, q1 + q2 + q3]
         #  common_attn_metadata.seq_lens{_cpu}: [s1, s2, s3]
         #  num_rejected_tokens: [n1, n2, n3]
         # This function computes the intermediate values:
         #  num_tokens_per_req: [q1 - n1, q2 - n2, q3 - n3]
         # And returns:
         #  common_attn_metadata.query_start_loc{_cpu}:
-        #         [0, q1 - n1, q1 + q2 - n1 - n2, q1 + q2 + q3 - n1 - n2 - n3]
+        #       [0, q1 - n1, q1 + q2 - n1 - n2, q1 + q2 + q3 - n1 - n2 - n3]
         #  common_attn_metadata.seq_lens{_cpu}:
-        #         [s1 - n1 + 1, s2 - n2 + 1, s3 - n3 + 1]
+        #       [s1 - n1 + 1, s2 - n2 + 1, s3 - n3 + 1]
         #  token_indices: [0, 1, ..., q1 - n1 - 1,
-        #                  q1, q1 + 1, ..., q1 + q2 - n2 - 1,
-        #                  q1 + q2, q1 + q2 + 1, ..., q1 + q2 + q3 - n3 - 1]
+        #                 q1, q1 + 1, ..., q1 + q2 - n2 - 1,
+        #                 q1 + q2, q1 + q2 + 1, ..., q1 + q2 + q3 - n3 - 1]
 
         device = common_attn_metadata.query_start_loc.device
         query_start_loc_cpu = common_attn_metadata.query_start_loc_cpu
@@ -564,9 +576,9 @@ def prepare_inputs(
         old_query_start_locs_expanded = np.repeat(
             query_start_loc_cpu[:-1].numpy(), new_num_tokens_per_req_np)
         # Final token indices are:
-        # [0, 1,                                   // req 1
-        #  q1 + 0, q1 + 1, q1 + 2, q1 + 3,         // req 2
-        #  q1 + q2 + 0, q1 + q2 + 1, q1 + q2 + 2]  // req 3
+        # [0, 1,                                // req 1
+        #  q1 + 0, q1 + 1, q1 + 2, q1 + 3,       // req 2
+        #  q1 + q2 + 0, q1 + q2 + 1, q1 + q2 + 2] // req 3
         token_indices_np = token_offests + old_query_start_locs_expanded
         token_indices = torch.from_numpy(token_indices_np).to(
             device, non_blocking=True)
@@ -615,20 +627,18 @@ def load_model(self, target_model: nn.Module) -> None:
             target_language_model = target_model
         # share embed_tokens with the target model if needed
         if get_pp_group().world_size == 1 \
-            and self.model.model.embed_tokens.weight.shape \
-                == target_language_model.model.embed_tokens.weight.shape:
+                and self.model.model.embed_tokens.weight.shape \
+            == target_language_model.model.embed_tokens.weight.shape:
             logger.info(
-                "Assuming the EAGLE head shares the same vocab embedding" \
-                " with the target model."
-            )
+                "Assuming the EAGLE head shares the same vocab embedding"
+                " with the target model.")
             del self.model.model.embed_tokens
             self.model.model.embed_tokens = (
                 target_language_model.model.embed_tokens)
         else:
             logger.info(
-                "The EAGLE head's vocab embedding will be loaded separately" \
-                " from the target model."
-            )
+                "The EAGLE head's vocab embedding will be loaded separately"
+                " from the target model.")
 
         # share lm_head with the target model if needed
         # some model definition do not define lm_head explicitly