[TRTLLM-12982][perf] reuse multi-item scoring position_ids and params (#15413)

Signed-off-by: ixlmar <206748156+ixlmar@users.noreply.github.com>

Author: ixlmar

tensorrt_llm/_torch/attention_backend/flashinfer.py

@@ -1,16 +1,23 @@
 import functools
 import math
 import os
+import sys
 import weakref
 from dataclasses import dataclass, field
 from typing import Any, Dict, Literal, NewType, Optional, TypeAlias, cast
 
+if sys.version_info[:2] >= (3, 12):
+    from typing import override
+else:
+    from typing_extensions import override
+
 import flashinfer
 import torch
 from flashinfer.jit.core import check_cuda_arch
 from typing_extensions import Self
 
 from tensorrt_llm._torch.pyexecutor.sampling_utils import torch_multi_arange
+from tensorrt_llm._utils import nvtx_range
 from tensorrt_llm.functional import AttentionMaskType
 from tensorrt_llm.logger import logger
 from tensorrt_llm.models.modeling_utils import QuantConfig
@@ -157,6 +164,9 @@ class FlashInferAttentionMetadata(AttentionMetadata):
     _mla_kv_len_arr_buf: Optional[torch.Tensor] = field(init=False,
                                                         default=None)
 
+    _multi_item_params: Optional[FlashInferMultiItemParams] = field(
+        init=False, default=None)
+
     def needs_plan(self, plan_params: PlanParams) -> bool:
         if plan_params not in self._plan_params_to_wrappers:
             return True
@@ -595,6 +605,7 @@ def _post_init_with_buffers(self, buffers) -> None:
         self._mla_ragged_planned = False
         self._mla_context_planned = False
         self._mla_decode_planned = False
+        self._multi_item_params = None
 
     def create_cuda_graph_metadata(self,
                                    max_batch_size: int,
@@ -722,6 +733,89 @@ def _plan_ragged_no_kv(
             **plan_kwargs,
         )
 
+    def _process_multi_item_part_lens(
+        self,
+        multi_item_part_lens: list[list[int]],
+        *,
+        device: torch.device,
+    ) -> FlashInferMultiItemParams:
+        if self.num_generations > 0:
+            raise ValueError(
+                "\"multi_item_part_lens\" not supported for generation requests."
+            )
+        if len(multi_item_part_lens) != self.num_contexts:
+            raise ValueError(
+                "\"multi_item_part_lens\" needs to be provided for all requests."
+            )
+
+        prefix_len_ptr = torch.tensor(
+            [req_part_lens[0] for req_part_lens in multi_item_part_lens],
+            pin_memory=prefer_pinned(),
+            dtype=torch.uint32,
+        ).to(device=device, non_blocking=True)
+        token_pos_in_items_raw_lens = [  # 'raw' lengths before padding
+            sum(req_part_lens[1:]) + len(req_part_lens)
+            for req_part_lens in multi_item_part_lens
+        ]
+        token_pos_in_items_len = max(token_pos_in_items_raw_lens)
+        max_item_len_ptr = torch.tensor(
+            [max(req_part_lens[1:]) for req_part_lens in multi_item_part_lens],
+            pin_memory=prefer_pinned(),
+            dtype=torch.uint16,
+        ).to(device=device, non_blocking=True)
+
+        # token_pos_in_items_ptr is obtained by concatenating range(item_len + 1) for each item in
+        # every request, followed by [0] (final delimiter) which is fused with padding for simplicity.
+        range_ends = torch.tensor(
+            [
+                item_len + 1
+                for req_part_lens, token_pos_in_items_raw_len in zip(
+                    multi_item_part_lens, token_pos_in_items_raw_lens)
+                for item_len in (
+                    req_part_lens[1:] +
+                    [token_pos_in_items_len - token_pos_in_items_raw_len])
+            ],
+            pin_memory=prefer_pinned(),
+            dtype=torch.int32,
+        ).to(device=device, non_blocking=True)
+        token_pos_in_items_ptr = torch_multi_arange(
+            range_ends,
+            output_length=(token_pos_in_items_len * len(multi_item_part_lens)),
+        )
+        # next, mask out the padding
+        mask_entries = torch.arange(2, dtype=torch.uint8).to(
+            device=device,
+            non_blocking=True,
+            dtype=torch.bool,
+        ).repeat(len(multi_item_part_lens))  # NB: .expand() does not work here
+        mask_entry_repeats = torch.tensor(
+            [
+                repeat
+                for token_pos_in_items_raw_len in token_pos_in_items_raw_lens
+                for repeat in [
+                    token_pos_in_items_raw_len,
+                    token_pos_in_items_len - token_pos_in_items_raw_len,
+                ]
+            ],
+            pin_memory=prefer_pinned(),
+            dtype=torch.int32,
+        ).to(device=device, non_blocking=True)
+        padding_mask = torch.repeat_interleave(
+            input=mask_entries,
+            repeats=mask_entry_repeats,
+            output_size=token_pos_in_items_ptr.size(0),
+        )
+        token_pos_in_items_ptr.masked_fill_(padding_mask, 0)
+        token_pos_in_items_ptr = token_pos_in_items_ptr.to(dtype=torch.uint16,
+                                                           non_blocking=True)
+
+        return FlashInferMultiItemParams(
+            prefix_len_ptr=prefix_len_ptr,
+            max_item_len_ptr=max_item_len_ptr,
+            token_pos_in_items_ptr=token_pos_in_items_ptr,
+            token_pos_in_items_len=token_pos_in_items_len,
+        )
+
     def _clean_cached_plans(self, *, defer_plan: bool):
         for plan_params in list(self._plan_params_to_wrappers.keys()):
             # Generally, plan_params with non-trivial attention masking are relevant only the
@@ -740,11 +834,18 @@ def prepare(self) -> None:
         if extra_attrs is None:
             get_global_attrs().attention_metadata = weakref.ref(self)
         # start and end indices of each sequence in the ragged query
+        assert self.seq_lens_cuda is not None
         torch.cumsum(self.seq_lens_cuda,
                      dim=0,
                      dtype=torch.int32,
                      out=self._qo_indptr[1:self.seq_lens_cuda.size(0) + 1])
 
+        if self.multi_item_part_lens is not None:
+            self._multi_item_params = self._process_multi_item_part_lens(
+                self.multi_item_part_lens, device=self.seq_lens_cuda.device)
+        else:
+            self._multi_item_params = None
+
         if self.kv_cache_manager is None:
             assert self.request_ids is not None
             assert self.num_generations == 0, (
@@ -761,6 +862,10 @@ def prepare(self) -> None:
             self._clean_cached_plans(defer_plan=False)
             return
 
+        if self._multi_item_params is not None:
+            raise ValueError(
+                "multi_item_part_lens with KV cache is not supported")
+
         # indices of used cache blocks for each sequence
         assert self.request_ids is not None
         block_ids_per_seq = self.kv_cache_manager.get_batch_cache_indices(
@@ -1009,7 +1114,6 @@ def plan(self,
              q_scaling: Optional[float] = None,
              attention_window_size: Optional[int] = None,
              attention_mask_data: Optional[torch.Tensor] = None,
-             multi_item_params: Optional[FlashInferMultiItemParams] = None,
              flashinfer_backend: str = "fa2") -> PlanParams:
 
         sm_scale = None
@@ -1027,7 +1131,7 @@ def plan(self,
             if attention_window_size is not None else -1,
             attention_mask_type=AttentionMaskType(attention_mask_type),
             attention_mask_data=attention_mask_data,
-            multi_item_params=multi_item_params,
+            multi_item_params=self._multi_item_params,
         )
         return self._plan_with_params(plan_params, flashinfer_backend)
 
@@ -1214,6 +1318,11 @@ class FlashInferAttention(AttentionBackend[FlashInferAttentionMetadata]):
     def support_mla(cls) -> bool:
         return True
 
+    @override
+    @classmethod
+    def support_multi_item_scoring(cls) -> bool:
+        return True
+
     def __init__(
         self,
         layer_idx: int,
@@ -1247,90 +1356,6 @@ def update_quant_config(self, new_quant_config: Optional[QuantConfig]):
             self.has_fp8_kv_cache = self.quant_config.layer_quant_mode.has_fp8_kv_cache(
             )
 
-    @staticmethod
-    def _process_multi_item_part_lens(
-        multi_item_part_lens: list[list[int]],
-        *,
-        metadata: FlashInferAttentionMetadata,
-        device: torch.device,
-    ) -> FlashInferMultiItemParams:
-        if metadata.num_generations > 0:
-            raise ValueError(
-                "\"multi_item_part_lens\" not supported for generation requests."
-            )
-        if len(multi_item_part_lens) != metadata.num_contexts:
-            raise ValueError(
-                "\"multi_item_part_lens\" needs to be provided for all requests."
-            )
-
-        prefix_len_ptr = torch.tensor(
-            [req_part_lens[0] for req_part_lens in multi_item_part_lens],
-            pin_memory=prefer_pinned(),
-            dtype=torch.uint32,
-        ).to(device=device, non_blocking=True)
-        token_pos_in_items_raw_lens = [  # 'raw' lengths before padding
-            sum(req_part_lens[1:]) + len(req_part_lens)
-            for req_part_lens in multi_item_part_lens
-        ]
-        token_pos_in_items_len = max(token_pos_in_items_raw_lens)
-        max_item_len_ptr = torch.tensor(
-            [max(req_part_lens[1:]) for req_part_lens in multi_item_part_lens],
-            pin_memory=prefer_pinned(),
-            dtype=torch.uint16,
-        ).to(device=device, non_blocking=True)
-
-        # token_pos_in_items_ptr is obtained by concatenating range(item_len + 1) for each item in
-        # every request, followed by [0] (final delimiter) which is fused with padding for simplicity.
-        range_ends = torch.tensor(
-            [
-                item_len + 1
-                for req_part_lens, token_pos_in_items_raw_len in zip(
-                    multi_item_part_lens, token_pos_in_items_raw_lens)
-                for item_len in (
-                    req_part_lens[1:] +
-                    [token_pos_in_items_len - token_pos_in_items_raw_len])
-            ],
-            pin_memory=prefer_pinned(),
-            dtype=torch.int32,
-        ).to(device=device, non_blocking=True)
-        token_pos_in_items_ptr = torch_multi_arange(
-            range_ends,
-            output_length=(token_pos_in_items_len * len(multi_item_part_lens)),
-        )
-        # next, mask out the padding
-        mask_entries = torch.arange(2, dtype=torch.uint8).to(
-            device=device,
-            non_blocking=True,
-            dtype=torch.bool,
-        ).repeat(len(multi_item_part_lens))  # NB: .expand() does not work here
-        mask_entry_repeats = torch.tensor(
-            [
-                repeat
-                for token_pos_in_items_raw_len in token_pos_in_items_raw_lens
-                for repeat in [
-                    token_pos_in_items_raw_len,
-                    token_pos_in_items_len - token_pos_in_items_raw_len,
-                ]
-            ],
-            pin_memory=prefer_pinned(),
-            dtype=torch.int32,
-        ).to(device=device, non_blocking=True)
-        padding_mask = torch.repeat_interleave(
-            input=mask_entries,
-            repeats=mask_entry_repeats,
-            output_size=token_pos_in_items_ptr.size(0),
-        )
-        token_pos_in_items_ptr.masked_fill_(padding_mask, 0)
-        token_pos_in_items_ptr = token_pos_in_items_ptr.to(dtype=torch.uint16,
-                                                           non_blocking=True)
-
-        return FlashInferMultiItemParams(
-            prefix_len_ptr=prefix_len_ptr,
-            max_item_len_ptr=max_item_len_ptr,
-            token_pos_in_items_ptr=token_pos_in_items_ptr,
-            token_pos_in_items_len=token_pos_in_items_len,
-        )
-
     def mla_rope_generation(
         self,
         fused_q: torch.Tensor,
@@ -1610,7 +1635,6 @@ def forward_impl(
         output: torch.Tensor,
         attention_mask_data: Optional[torch.Tensor] = None,
         attention_window_size: Optional[int] = None,
-        multi_item_part_lens: Optional[list[list[int]]] = None,
         latent_cache: Optional[torch.Tensor] = None,
         attention_input_type: AttentionInputType = AttentionInputType.mixed,
     ) -> None:
@@ -1648,14 +1672,6 @@ def forward_impl(
         # Query
         q = q.view(-1, self.num_heads, self.head_dim)
 
-        multi_item_params: FlashInferMultiItemParams | None = None
-        if multi_item_part_lens is not None:
-            multi_item_params = self._process_multi_item_part_lens(
-                multi_item_part_lens,
-                metadata=metadata,
-                device=q.device,
-            )
-
         if metadata.kv_cache_manager is None:
             assert k is not None and v is not None, (
                 "FlashInfer without a KV cache manager requires key/value tensors."
@@ -1670,18 +1686,18 @@ def forward_impl(
             assert v.shape == (q.size(0), self.num_kv_heads * self.head_dim)
             k = k.view(-1, self.num_kv_heads, self.head_dim)
             v = v.view(-1, self.num_kv_heads, self.head_dim)
-            plan_params = metadata.plan(
-                self.num_heads,
-                self.num_kv_heads,
-                self.head_dim,
-                q_dtype=q.dtype,
-                kv_dtype=k.dtype,
-                q_scaling=self.q_scaling,
-                attention_window_size=attention_window_size,
-                attention_mask_type=attention_mask_type,
-                attention_mask_data=attention_mask_data,
-                multi_item_params=multi_item_params,
-            )
+            with nvtx_range("metadata.plan"):
+                plan_params = metadata.plan(
+                    self.num_heads,
+                    self.num_kv_heads,
+                    self.head_dim,
+                    q_dtype=q.dtype,
+                    kv_dtype=k.dtype,
+                    q_scaling=self.q_scaling,
+                    attention_window_size=attention_window_size,
+                    attention_mask_type=attention_mask_type,
+                    attention_mask_data=attention_mask_data,
+                )
             wrapper = metadata.get_ragged_prefill_wrapper(plan_params)
             if isinstance(wrapper,
                           flashinfer.BatchPrefillWithPagedKVCacheWrapper):
@@ -1700,11 +1716,6 @@ def forward_impl(
                 )
             return
 
-        if multi_item_part_lens is not None:
-            raise ValueError(
-                "Multi-item masking support not implemented for paged KV cache."
-            )
-
         # Key and Value
         kv_cache = metadata.kv_cache_manager.get_buffers(
             self.layer_idx, kv_layout=metadata.kv_layout)
@@ -1901,6 +1912,5 @@ def forward(self,
             output=output,
             latent_cache=latent_cache,
             attention_input_type=forward_args.attention_input_type,
-            multi_item_part_lens=forward_args.multi_item_part_lens,
         )
         return output

tensorrt_llm/_torch/attention_backend/interface.py

@@ -174,6 +174,13 @@ class AttentionMetadata:
     # The number of heads per kv head.
     num_heads_per_kv: Optional[int] = 1
 
+    multi_item_part_lens: Optional[list[list[int]]] = None
+    """Additional token layout information for multi-item scoring.
+
+    Aggregates `TokensPrompt.multi_item_part_lens` for all requests in the batch,
+    see `TokensPrompt` for details.
+    """
+
     def __post_init__(self) -> None:
         if self.is_cross:
             assert self.cross is None or self.cross is self, "Cross attention metadata should not have sub metadata"
@@ -835,13 +842,6 @@ class AttentionForwardArgs:
     relative_attention_max_distance: int = 0
     cross_kv: Optional[torch.Tensor] = None
 
-    multi_item_part_lens: Optional[list[list[int]]] = None
-    """Additional token layout information for multi-item scoring.
-
-    Aggregates `TokensPrompt.multi_item_part_lens` for all requests in the batch,
-    see `TokensPrompt` for details.
-    """
-
     latent_cache: Optional[torch.Tensor] = None
     q_pe: Optional[torch.Tensor] = None
     mrope_rotary_cos_sin: Optional[torch.Tensor] = None
@@ -984,6 +984,10 @@ def support_fused_qkv(cls) -> bool:
     def support_mla(cls) -> bool:
         return False
 
+    @classmethod
+    def support_multi_item_scoring(cls) -> bool:
+        return False
+
     def create_output(self, q: torch.Tensor, **kwargs) -> List[torch.Tensor]:
         """
         Create the output tensors for the attention operation.