[feat] feat: support swa in trtllm_mha (#18970)

This commit is contained in:
0xNullPath
2026-02-21 01:39:29 +08:00
committed by GitHub
parent fbb6098487
commit ab18734375

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@@ -20,6 +20,7 @@ from sglang.srt.layers.attention.triton_ops.trtllm_fp8_kv_kernel import (
fused_fp8_set_kv_buffer,
)
from sglang.srt.layers.attention.utils import canonicalize_stride
from sglang.srt.mem_cache.swa_memory_pool import SWAKVPool, SWATokenToKVPoolAllocator
from sglang.srt.model_executor.forward_batch_info import ForwardBatch, ForwardMode
from sglang.srt.utils import is_flashinfer_available
@@ -56,6 +57,8 @@ class TRTLLMMHAMetadata:
cu_seqlens_k: torch.Tensor = None
# Page table, the index of KV Cache Tables/Blocks
page_table: torch.Tensor = None
# Page table for SWA layers (translated from full pool indices to SWA pool indices)
swa_page_table: torch.Tensor = None
class TRTLLMHAAttnBackend(FlashInferAttnBackend):
@@ -120,9 +123,71 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
model_runner.server_args.speculative_num_draft_tokens
)
# Sliding Window Attention(SWA) hybrid model support.
# For hybrid SWA models, the KV cache is split into two pools (full and SWA)
# with separate index spaces. We maintain a translated page_table for SWA
# layers so the trtllm kernel reads from the correct pool.
allocator = model_runner.token_to_kv_pool_allocator
self.use_sliding_window_kv_pool = isinstance(
allocator, SWATokenToKVPoolAllocator
)
self._swa_kv_pool: Optional[SWAKVPool] = (
allocator.get_kvcache() if self.use_sliding_window_kv_pool else None
)
# Forward metadata
self.forward_metadata: Optional[TRTLLMMHAMetadata] = None
def _maybe_translate_swa(
self, token_indices: torch.Tensor
) -> Optional[torch.Tensor]:
"""Translate full-pool token indices to SWA-pool indices, or return None."""
if not self.use_sliding_window_kv_pool:
return None
shape = token_indices.shape
return self._swa_kv_pool.translate_loc_from_full_to_swa(
token_indices.reshape(-1)
).reshape(shape)
def _alloc_swa_page_table(
self, max_bs: int, max_num_pages: int
) -> Optional[torch.Tensor]:
"""Allocate a SWA page_table buffer, or return None for non-SWA models."""
if not self.use_sliding_window_kv_pool:
return None
return torch.zeros(max_bs, max_num_pages, dtype=torch.int32, device=self.device)
def _copy_swa_page_table(
self,
metadata: TRTLLMMHAMetadata,
page_indices: torch.Tensor,
num_pages: int,
):
"""Translate and copy SWA page indices into metadata. No-op for non-SWA."""
if metadata.swa_page_table is None:
return
swa_indices = self._maybe_translate_swa(page_indices)
metadata.swa_page_table[:, :num_pages].copy_(swa_indices // self.page_size)
def _bind_swa_page_table(
self, metadata: TRTLLMMHAMetadata, source: dict, key: str, bs: int
):
"""Bind a pre-allocated SWA page_table slice to metadata for CUDA graph."""
buf = source.get(key)
if buf is not None:
metadata.swa_page_table = buf[:bs, :]
def _get_layer_page_table(
self, layer: RadixAttention, forward_batch: ForwardBatch
) -> torch.Tensor:
"""Return the correct page_table for the given layer (SWA or full)."""
swa_pt = self.forward_metadata.swa_page_table
if swa_pt is not None:
_, is_swa = self._swa_kv_pool.layers_mapping[layer.layer_id]
if is_swa:
return swa_pt
return self.forward_metadata.page_table
def init_cuda_graph_state(
self,
max_bs: int,
@@ -139,6 +204,7 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
dtype=torch.int32,
device=self.device,
),
"swa_page_table": self._alloc_swa_page_table(max_bs, max_num_pages),
"strided_indices": torch.arange(
0, self.max_context_len, self.page_size, device=self.device
),
@@ -160,6 +226,10 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
dtype=torch.int32,
device=self.device,
)
self.decode_cuda_graph_metadata["swa_page_table_draft_decode"] = (
self._alloc_swa_page_table(max_bs, max_num_pages)
)
self.target_verify_metadata = {
"cache_seqlens": torch.zeros(
max_bs, dtype=torch.int32, device=self.device
@@ -180,6 +250,7 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
dtype=torch.int32,
device=self.device,
),
"swa_page_table": self._alloc_swa_page_table(max_bs, max_num_pages),
"strided_indices": torch.arange(
0, self.max_context_len, self.page_size, device=self.device
),
@@ -203,6 +274,7 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
dtype=torch.int32,
device=self.device,
),
"swa_page_table": self._alloc_swa_page_table(max_bs, max_num_pages),
"strided_indices": torch.arange(
0, self.max_context_len, self.page_size, device=self.device
),
@@ -244,6 +316,12 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
metadata.page_table = self.decode_cuda_graph_metadata[
"page_table_draft_decode"
][:bs, :]
self._bind_swa_page_table(
metadata,
self.decode_cuda_graph_metadata,
"swa_page_table_draft_decode",
bs,
)
self.decode_cuda_graph_metadata[bs] = metadata
else:
# Normal Decode
@@ -264,6 +342,12 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
metadata.page_table = self.decode_cuda_graph_metadata["page_table"][
:bs, :
]
self._bind_swa_page_table(
metadata,
self.decode_cuda_graph_metadata,
"swa_page_table",
bs,
)
self.decode_cuda_graph_metadata[bs] = metadata
elif forward_mode.is_target_verify():
# Target Verify
@@ -293,6 +377,12 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
)
metadata.page_table = self.target_verify_metadata["page_table"][:bs, :]
self._bind_swa_page_table(
metadata,
self.target_verify_metadata,
"swa_page_table",
bs,
)
self.target_verify_metadata[bs] = metadata
elif forward_mode.is_draft_extend():
@@ -317,6 +407,12 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
metadata.max_seq_len_k = seq_lens.max().item()
metadata.page_table = self.draft_extend_metadata["page_table"][:bs, :]
self._bind_swa_page_table(
metadata,
self.draft_extend_metadata,
"swa_page_table",
bs,
)
self.draft_extend_metadata[bs] = metadata
self.forward_metadata = metadata
@@ -371,6 +467,7 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
],
]
metadata.page_table[:, :max_seq_pages].copy_(page_indices // self.page_size)
self._copy_swa_page_table(metadata, page_indices, max_seq_pages)
elif forward_mode.is_target_verify():
# Here we only support topk = 1 for now.
metadata = self.target_verify_metadata[bs]
@@ -392,8 +489,8 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
req_pool_indices[:, None],
self.decode_cuda_graph_metadata["strided_indices"][:max_seq_pages],
]
page_indices //= self.page_size
metadata.page_table[:, :max_seq_pages].copy_(page_indices)
metadata.page_table[:, :max_seq_pages].copy_(page_indices // self.page_size)
self._copy_swa_page_table(metadata, page_indices, max_seq_pages)
metadata.max_seq_len_q = self.speculative_num_draft_tokens
elif forward_mode.is_draft_extend():
metadata = self.draft_extend_metadata[bs]
@@ -422,6 +519,7 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
self.draft_extend_metadata["strided_indices"][:max_seq_pages],
]
metadata.page_table[:, :max_seq_pages].copy_(page_indices // self.page_size)
self._copy_swa_page_table(metadata, page_indices, max_seq_pages)
self.forward_metadata = metadata
def get_cuda_graph_seq_len_fill_value(self) -> int:
@@ -553,7 +651,10 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
metadata.max_seq_len_q = metadata.max_seq_len_k
metadata.cu_seqlens_q = metadata.cu_seqlens_k
# Convert the page table to a strided format
# Compute SWA page table (None for non-SWA models)
metadata.swa_page_table = self._maybe_translate_swa(metadata.page_table)
# Convert the page tables to a strided format
if self.page_size > 1:
self.strided_indices = torch.arange(
0, metadata.page_table.shape[1], self.page_size, device=self.device
@@ -561,6 +662,10 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
metadata.page_table = (
metadata.page_table[:, self.strided_indices] // self.page_size
)
if metadata.swa_page_table is not None:
metadata.swa_page_table = (
metadata.swa_page_table[:, self.strided_indices] // self.page_size
)
self.forward_metadata = metadata
@@ -629,19 +734,20 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
# sink: additional value per head in the denominator of the softmax.
attention_sink = kwargs.get("sinks", None)
page_table = self._get_layer_page_table(layer, forward_batch)
# Call TRT-LLM kernel
# raw_out: like q, [bs, acc_q_len, num_q_heads, head_dim] but with output dtype
o = flashinfer.decode.trtllm_batch_decode_with_kv_cache(
query=q,
kv_cache=kv_cache,
workspace_buffer=self.workspace_buffer,
block_tables=self.forward_metadata.page_table,
block_tables=page_table,
seq_lens=self.forward_metadata.cache_seqlens_int32,
max_seq_len=self.max_context_len,
bmm1_scale=bmm1_scale,
bmm2_scale=bmm2_scale,
window_left=layer.sliding_window_size,
# TODO: add attention_sink operation or nvfp4 scale factor if needed
sinks=attention_sink,
out_dtype=self.q_data_type, # model_runner.dtype
)
@@ -711,29 +817,29 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
bmm1_scale = q_scale * k_scale * layer.scaling
bmm2_scale = 1.0
page_table = self._get_layer_page_table(layer, forward_batch)
if forward_batch.forward_mode.is_target_verify():
o = flashinfer.decode.trtllm_batch_decode_with_kv_cache(
query=q,
kv_cache=kv_cache,
workspace_buffer=self.workspace_buffer,
block_tables=self.forward_metadata.page_table,
block_tables=page_table,
seq_lens=self.forward_metadata.cache_seqlens_int32,
max_seq_len=self.max_context_len,
bmm1_scale=bmm1_scale,
bmm2_scale=bmm2_scale,
window_left=layer.sliding_window_size,
# TODO: add attention_sink operation or nvfp4 scale factor if needed
sinks=attention_sink,
out_dtype=self.q_data_type, # model_runner.dtype
q_len_per_req=self.forward_metadata.max_seq_len_q,
)
else:
o = flashinfer.prefill.trtllm_batch_context_with_kv_cache(
query=q,
kv_cache=kv_cache,
workspace_buffer=self.workspace_buffer,
block_tables=self.forward_metadata.page_table,
block_tables=page_table,
seq_lens=self.forward_metadata.cache_seqlens_int32,
max_q_len=self.forward_metadata.max_seq_len_q,
max_kv_len=self.max_context_len,
@@ -743,7 +849,6 @@ class TRTLLMHAAttnBackend(FlashInferAttnBackend):
cum_seq_lens_q=self.forward_metadata.cu_seqlens_q,
cum_seq_lens_kv=self.forward_metadata.cu_seqlens_k,
window_left=layer.sliding_window_size,
# TODO: add attention_sink operation or nvfp4 scale factor if needed
sinks=attention_sink,
out_dtype=self.q_data_type, # model_runner.dtype
)