[Core] Factor out common logic for MM budget calculation (#22228)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

vllm/v1/worker/gpu_model_runner.py

@@ -36,7 +36,8 @@ from vllm.model_executor.models.interfaces import (is_mixture_of_experts,
 from vllm.model_executor.models.interfaces_base import (
     VllmModelForPooling, is_pooling_model, is_text_generation_model)
 from vllm.multimodal import MULTIMODAL_REGISTRY
-from vllm.multimodal.inputs import MultiModalKwargs, PlaceholderRange
+from vllm.multimodal.inputs import (BatchedTensorInputs, MultiModalKwargs,
+                                    PlaceholderRange)
 from vllm.multimodal.utils import group_mm_inputs_by_modality
 from vllm.pooling_params import PoolingParams
 from vllm.sampling_params import SamplingType
@@ -51,7 +52,6 @@ from vllm.v1.attention.backends.utils import (
     make_kv_sharing_fast_prefill_attention_metadata,
     make_local_attention_virtual_batches,
     reorder_batch_to_split_decodes_and_prefills)
-from vllm.v1.core.encoder_cache_manager import compute_encoder_budget
 from vllm.v1.kv_cache_interface import (AttentionSpec,
                                         ChunkedLocalAttentionSpec,
                                         FullAttentionSpec, KVCacheConfig,
@@ -73,7 +73,7 @@ from vllm.v1.worker.kv_connector_model_runner_mixin import (
 from vllm.v1.worker.lora_model_runner_mixin import LoRAModelRunnerMixin
 
 from ..sample.logits_processor import LogitsProcessorManager
-from .utils import (bind_kv_cache, gather_mm_placeholders,
+from .utils import (MultiModalBudget, bind_kv_cache, gather_mm_placeholders,
                     initialize_kv_cache_for_kv_sharing,
                     sanity_check_mm_encoder_outputs, scatter_mm_placeholders)
 
@@ -148,14 +148,6 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
         self.mm_registry = MULTIMODAL_REGISTRY
         self.uses_mrope = model_config.uses_mrope
 
-        encoder_compute_budget, encoder_cache_size = compute_encoder_budget(
-            model_config=model_config,
-            scheduler_config=scheduler_config,
-            mm_registry=self.mm_registry,
-        )
-        self.max_num_encoder_input_tokens = encoder_compute_budget
-        self.encoder_cache_size = encoder_cache_size
-
         # Sampler
         self.sampler = Sampler(logprobs_mode=self.model_config.logprobs_mode)
 
@@ -330,6 +322,14 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             self.kv_sharing_fast_prefill_logits_indices = torch.zeros(
                 self.max_num_tokens, dtype=torch.int32, device=self.device)
 
+        self.mm_budget = (MultiModalBudget(
+            self.model_config,
+            self.scheduler_config,
+            self.mm_registry,
+            max_model_len=self.max_model_len,
+            max_num_reqs=self.max_num_reqs,
+        ) if self.is_multimodal_model else None)
+
         self.reorder_batch_threshold: Optional[int] = None
 
     def _may_reorder_batch(self, scheduler_output: "SchedulerOutput") -> None:
@@ -578,37 +578,33 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
         # Refresh batch metadata with any pending updates.
         self.input_batch.refresh_metadata()
 
-    def _init_model_kwargs_for_multimodal_model(
+    def _extract_mm_kwargs(
         self,
-        scheduler_output: Optional["SchedulerOutput"] = None,
+        scheduler_output: "SchedulerOutput",
-        num_reqs: int = -1,
+    ) -> BatchedTensorInputs:
-    ) -> dict[str, Any]:
+        if self.is_multimodal_raw_input_supported:  # noqa: SIM102
-
-        model_kwargs: dict[str, Any] = {}
-        if self.is_multimodal_raw_input_supported:
-            # This model requires the raw multimodal data in input.
             if scheduler_output:
-                multi_modal_kwargs_list = []
+                multi_modal_kwargs_list = list[MultiModalKwargs]()
                 for req in scheduler_output.scheduled_new_reqs:
                     req_mm_inputs = req.mm_inputs
                     if not isinstance(req_mm_inputs, list):
                         req_mm_inputs = list(req_mm_inputs)
                     multi_modal_kwargs_list.extend(req_mm_inputs)
-                multi_modal_kwargs = MultiModalKwargs.batch(
-                    multi_modal_kwargs_list)
-            else:
-                # The only case where SchedulerOutput is None is for
-                # a dummy run let's get some dummy data.
-                dummy_data = [
-                    self.mm_registry.get_decoder_dummy_data(
-                        model_config=self.model_config,
-                        seq_len=1).multi_modal_data for i in range(num_reqs)
-                ]
-                multi_modal_kwargs = MultiModalKwargs.batch(dummy_data)
 
-            model_kwargs.update(multi_modal_kwargs)
+                return MultiModalKwargs.batch(multi_modal_kwargs_list)
 
-        return model_kwargs
+        return {}
+
+    def _dummy_mm_kwargs(self, num_seqs: int) -> BatchedTensorInputs:
+        if self.is_multimodal_raw_input_supported:
+            mm_budget = self.mm_budget
+            assert mm_budget is not None
+
+            dummy_modality, _ = mm_budget.get_modality_with_max_tokens()
+
+            return self._get_mm_dummy_batch(dummy_modality, num_seqs)
+
+        return {}
 
     def _get_cumsum_and_arange(
         self,
@@ -1517,19 +1513,18 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             # NOTE(woosuk): To unify token ids and soft tokens (vision
             # embeddings), we always use embeddings (rather than token ids)
             # as input to the multimodal model, even when the input is text.
-            input_ids = self.input_ids[:num_scheduled_tokens]
+            inputs_embeds_scheduled = self.model.get_input_embeddings(
-
+                input_ids=self.input_ids[:num_scheduled_tokens],
-            model_kwargs = self._init_model_kwargs_for_multimodal_model(
-                scheduler_output=scheduler_output)
-            inputs_embeds = self.model.get_input_embeddings(
-                input_ids=input_ids,
                 multimodal_embeddings=mm_embeds or None,
             )
 
             # TODO(woosuk): Avoid the copy. Optimize.
-            self.inputs_embeds[:num_scheduled_tokens].copy_(inputs_embeds)
+            self.inputs_embeds[:num_scheduled_tokens].copy_(
-            inputs_embeds = self.inputs_embeds[:num_input_tokens]
+                inputs_embeds_scheduled)
+
             input_ids = None
+            inputs_embeds = self.inputs_embeds[:num_input_tokens]
+            model_mm_kwargs = self._extract_mm_kwargs(scheduler_output)
         else:
             # For text-only models, we use token ids as input.
             # While it is possible to use embeddings as input just like the
@@ -1537,7 +1532,7 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             # then the embedding layer is not included in the CUDA graph.
             input_ids = self.input_ids[:num_input_tokens]
             inputs_embeds = None
-            model_kwargs = {}
+            model_mm_kwargs = {}
         if self.uses_mrope:
             positions = self.mrope_positions[:, :num_input_tokens]
         else:
@@ -1571,7 +1566,7 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
                 intermediate_tensors=intermediate_tensors,
                 inputs_embeds=inputs_embeds,
                 **MultiModalKwargs.as_kwargs(
-                    model_kwargs,
+                    model_mm_kwargs,
                     device=self.device,
                 ),
             )
@@ -2149,6 +2144,30 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             yield
             input_ids.fill_(0)
 
+    def _get_mm_dummy_batch(
+        self,
+        modality: str,
+        max_items_per_batch: int,
+    ) -> BatchedTensorInputs:
+        """Dummy data for profiling and precompiling multimodal models."""
+        dummy_decoder_data = self.mm_registry.get_decoder_dummy_data(
+            model_config=self.model_config,
+            seq_len=self.max_num_tokens,
+            mm_counts={modality: 1},
+        )
+        dummy_mm_data = dummy_decoder_data.multi_modal_data
+
+        # Result in the maximum GPU consumption of the model
+        dummy_mm_item = dummy_mm_data.get_item(modality=modality, item_index=0)
+        dummy_mm_kwargs = MultiModalKwargs.from_items([dummy_mm_item])
+
+        batched_dummy_mm_inputs = MultiModalKwargs.batch([dummy_mm_kwargs] *
+                                                         max_items_per_batch)
+        return MultiModalKwargs.as_kwargs(
+            batched_dummy_mm_inputs,
+            device=self.device,
+        )
+
     @torch.inference_mode()
     def _dummy_run(
         self,
@@ -2213,16 +2232,14 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
 
         with self.maybe_dummy_run_with_lora(self.lora_config,
                                             num_scheduled_tokens):
-            model = self.model
             if self.is_multimodal_model:
-                model_kwargs = self._init_model_kwargs_for_multimodal_model(
-                    num_reqs=num_reqs)
                 input_ids = None
                 inputs_embeds = self.inputs_embeds[:num_tokens]
+                model_mm_kwargs = self._dummy_mm_kwargs(num_reqs)
             else:
                 input_ids = self.input_ids[:num_tokens]
                 inputs_embeds = None
-                model_kwargs = {}
+                model_mm_kwargs = {}
 
             if self.uses_mrope:
                 positions = self.mrope_positions[:, :num_tokens]
@@ -2247,13 +2264,13 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
                     self.vllm_config,
                     num_tokens=num_tokens,
                     num_tokens_across_dp=num_tokens_across_dp):
-                outputs = model(
+                outputs = self.model(
                     input_ids=input_ids,
                     positions=positions,
                     intermediate_tensors=intermediate_tensors,
                     inputs_embeds=inputs_embeds,
                     **MultiModalKwargs.as_kwargs(
-                        model_kwargs,
+                        model_mm_kwargs,
                         device=self.device,
                     ),
                 )
@@ -2423,62 +2440,37 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
 
     def profile_run(self) -> None:
         # Profile with multimodal encoder & encoder cache.
-        # TODO: handle encoder-decoder models once we support them.
+        if self.is_multimodal_model:
-        if (self.is_multimodal_model and self.max_num_encoder_input_tokens > 0
+            mm_budget = self.mm_budget
-                and self.encoder_cache_size > 0):
+            assert mm_budget is not None
 
+            # TODO: handle encoder-decoder models once we support them.
+            if (encoder_budget := mm_budget.get_encoder_budget()) > 0:
                 # NOTE: Currently model is profiled with a single non-text
                 # modality with the max possible input tokens even when
                 # it supports multiple.
-            max_tokens_by_modality_dict = self.mm_registry \
+                (
-                .get_max_tokens_per_item_by_nonzero_modality(self.model_config)
+                    dummy_modality,
-            dummy_data_modality, max_tokens_per_mm_item = max(
+                    max_tokens,
-                max_tokens_by_modality_dict.items(), key=lambda item: item[1])
+                ) = mm_budget.get_modality_with_max_tokens()
-
+                (
-            # Check how many items of this modality can be supported by
+                    max_mm_items_per_prompt,
-            # the encoder budget.
+                    max_mm_items_per_batch,
-            encoder_budget = min(self.max_num_encoder_input_tokens,
+                ) = mm_budget.get_max_items(dummy_modality, max_tokens)
-                                 self.encoder_cache_size)
-
-            max_num_mm_items_encoder_budget = encoder_budget // \
-                max_tokens_per_mm_item
-
-            # Check how many items of this modality can be supported by
-            # the decoder budget.
-            max_mm_items_per_req = self.mm_registry.get_mm_limits_per_prompt(
-                self.model_config)[dummy_data_modality]
-
-            # NOTE: We do not consider max_num_batched_tokens on purpose
-            # because the multimodal embeddings can be generated in advance
-            # and chunked prefilled.
-            max_num_mm_items_decoder_budget = self.max_num_reqs * \
-                max_mm_items_per_req
-
-            max_num_mm_items = max(
-                1,
-                min(max_num_mm_items_encoder_budget,
-                    max_num_mm_items_decoder_budget))
 
                 logger.info(
-                "Encoder cache will be initialized with a budget of %s tokens,"
+                    "Encoder cache will be initialized with a budget of "
-                " and profiled with %s %s items of the maximum feature size.",
+                    "%s tokens, and profiled with %s %s items of the maximum "
-                encoder_budget, max_num_mm_items, dummy_data_modality)
+                    "feature size.",
+                    encoder_budget,
+                    max_mm_items_per_batch,
+                    dummy_modality,
+                )
 
                 # Create dummy batch of multimodal inputs.
-            dummy_mm_kwargs = self.mm_registry.get_decoder_dummy_data(
+                batched_dummy_mm_inputs = self._get_mm_dummy_batch(
-                model_config=self.model_config,
+                    dummy_modality,
-                seq_len=max_tokens_per_mm_item,
+                    max_mm_items_per_batch,
-                mm_counts={
-                    dummy_data_modality: 1
-                },
-            ).multi_modal_data
-
-            batched_dummy_mm_inputs = MultiModalKwargs.batch(
-                [dummy_mm_kwargs] * max_num_mm_items,
-                pin_memory=self.pin_memory)
-            batched_dummy_mm_inputs = MultiModalKwargs.as_kwargs(
-                batched_dummy_mm_inputs,
-                device=self.device,
                 )
 
                 # Run multimodal encoder.
@@ -2487,11 +2479,12 @@ class GPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
 
                 sanity_check_mm_encoder_outputs(
                     dummy_encoder_outputs,
-                expected_num_items=max_num_mm_items,
+                    expected_num_items=max_mm_items_per_batch,
                 )
 
                 # Cache the dummy encoder outputs.
-            self.encoder_cache["tmp"] = dict(enumerate(dummy_encoder_outputs))
+                self.encoder_cache["tmp"] = dict(
+                    enumerate(dummy_encoder_outputs))
 
         # Add `is_profile` here to pre-allocate communication buffers
         hidden_states, last_hidden_states \

vllm/v1/worker/tpu_model_runner.py

@@ -42,7 +42,6 @@ from vllm.v1.attention.backends.pallas import (TPU_STR_DTYPE_TO_TORCH_DTYPE,
                                                PallasAttentionBackend,
                                                PallasMetadata,
                                                get_page_size_bytes)
-from vllm.v1.core.encoder_cache_manager import compute_encoder_budget
 from vllm.v1.kv_cache_interface import (AttentionSpec, FullAttentionSpec,
                                         KVCacheConfig, KVCacheSpec,
                                         SlidingWindowSpec)
@@ -55,7 +54,8 @@ from vllm.v1.worker.kv_connector_model_runner_mixin import (
 from vllm.v1.worker.lora_model_runner_mixin import LoRAModelRunnerMixin
 from vllm.v1.worker.tpu_input_batch import CachedRequestState, InputBatch
 
-from .utils import (bind_kv_cache, initialize_kv_cache_for_kv_sharing,
+from .utils import (MultiModalBudget, bind_kv_cache,
+                    initialize_kv_cache_for_kv_sharing,
                     sanity_check_mm_encoder_outputs)
 
 if TYPE_CHECKING:
@@ -195,14 +195,6 @@ class TPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
         # TODO: Support M-RoPE (e.g, Qwen2-VL)
         assert not self.uses_mrope, "TPU does not support M-RoPE yet."
 
-        encoder_compute_budget, encoder_cache_size = compute_encoder_budget(
-            model_config=model_config,
-            scheduler_config=scheduler_config,
-            mm_registry=self.mm_registry,
-        )
-        self.max_num_encoder_input_tokens = encoder_compute_budget
-        self.encoder_cache_size = encoder_cache_size
-
         self._num_slices_per_kv_cache_update_block = \
             _get_num_slices_per_kv_cache_update_block(get_page_size_bytes(
                 block_size=self.block_size,
@@ -294,36 +286,13 @@ class TPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
         self.structured_decode_arange = torch.arange(
             0, 32, device="cpu", pin_memory=self.pin_memory)
 
-        # Get maximum number of mm items per modality (batch size).
+        self.mm_budget = (MultiModalBudget(
-        self.max_num_mm_items_by_modality = dict()
+            self.model_config,
-        if (self.is_multimodal_model and self.max_num_encoder_input_tokens > 0
+            self.scheduler_config,
-                and self.encoder_cache_size > 0):
+            self.mm_registry,
-            max_tokens_by_modality_dict = (
+            max_model_len=self.max_model_len,
-                MULTIMODAL_REGISTRY.
+            max_num_reqs=self.max_num_reqs,
-                get_max_tokens_per_item_by_nonzero_modality(self.model_config))
+        ) if self.is_multimodal_model else None)
-            for modality, max_tokens in max_tokens_by_modality_dict.items():
-                # Check how many items of this modality can be supported by
-                # the encoder budget.
-                encoder_budget = min(self.max_num_encoder_input_tokens,
-                                     self.encoder_cache_size)
-
-                max_num_mm_items_encoder_budget = cdiv(encoder_budget,
-                                                       max_tokens)
-
-                # Check how many items of this modality can be supported by
-                # the decoder budget.
-                max_mm_items_per_req = self.mm_registry.\
-                    get_mm_limits_per_prompt(self.model_config)[modality]
-
-                # NOTE: We do not consider max_num_batched_tokens on purpose
-                # because the multimodal embeddings can be generated in advance
-                # and chunked prefilled.
-                max_num_mm_items_decoder_budget = self.max_num_reqs * \
-                    max_mm_items_per_req
-
-                max_num_mm_items = min(max_num_mm_items_encoder_budget,
-                                       max_num_mm_items_decoder_budget)
-                self.max_num_mm_items_by_modality[modality] = max_num_mm_items
 
         if not self.use_spmd:
             self.sample_from_logits_func = torch.compile(
@@ -1335,23 +1304,33 @@ class TPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
         xm.mark_step()  # Captures metadata updates
 
     def _precompile_mm_encoder(self) -> None:
+        if not self.is_multimodal_model:
+            return
+
         # Pre-compile MM encoder for all supported data modalities.
         hf_config = self.vllm_config.model_config.hf_config
-        for mode, max_items_by_mode in \
+
-            self.max_num_mm_items_by_modality.items():
+        mm_budget = self.mm_budget
+        assert mm_budget is not None
+
+        max_items_per_seq_by_modality = mm_budget.max_items_per_batch_by_modality  # noqa: E501
+
+        for mode, max_items_per_seq in max_items_per_seq_by_modality.items():
             logger.info(
                 "Compiling Multimodal %s Encoder with different input"
                 " shapes.", mode)
             start = time.perf_counter()
             # No padding for MM encoder just yet.
-            for num_items in range(1, max_items_by_mode + 1):
+            for num_items in range(1, max_items_per_seq + 1):
                 logger.info("  -- mode: %s items: %d", mode, num_items)
                 batched_dummy_mm_inputs = self._get_mm_dummy_batch(
-                    mode, num_items)
+                    mode,
+                    num_items,
+                )
                 # Run multimodal encoder.
                 xm.mark_step()
-                mm_embeds = self.model.\
+                mm_embeds = self.model.get_multimodal_embeddings(
-                    get_multimodal_embeddings(**batched_dummy_mm_inputs)
+                    **batched_dummy_mm_inputs)
                 xm.mark_step()
                 num_patches = mm_embeds[0].shape[0]
                 items_size = num_patches * num_items
@@ -1547,27 +1526,38 @@ class TPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
         num_tokens: int,
     ) -> None:
         # Profile with multimodal encoder & encoder cache.
-        # TODO: handle encoder-decoder models once we support them.
+        if self.is_multimodal_model:
-        if (self.is_multimodal_model and self.max_num_encoder_input_tokens > 0
+            mm_budget = self.mm_budget
-                and self.encoder_cache_size > 0):
+            assert mm_budget is not None
 
+            # TODO: handle encoder-decoder models once we support them.
+            if (encoder_budget := mm_budget.get_encoder_budget()) > 0:
                 # NOTE: Currently model is profiled with a single non-text
                 # modality with the max possible input tokens even when
                 # it supports multiple.
-            dummy_data_modality, max_num_mm_items = max(
+                (
-                self.max_num_mm_items_by_modality.items(), key=lambda t: t[1])
+                    dummy_modality,
-
+                    max_tokens,
-            encoder_budget = min(self.max_num_encoder_input_tokens,
+                ) = mm_budget.get_modality_with_max_tokens()
-                                 self.encoder_cache_size)
+                (
+                    max_mm_items_per_prompt,
+                    max_mm_items_per_batch,
+                ) = mm_budget.get_max_items(dummy_modality, max_tokens)
 
                 logger.info(
-                "Encoder cache will be initialized with a budget of %d tokens,"
+                    "Encoder cache will be initialized with a budget of "
-                " and profiled with %s %s items of the maximum feature size.",
+                    "%s tokens, and profiled with %s %s items of the maximum "
-                encoder_budget, max_num_mm_items, dummy_data_modality)
+                    "feature size.",
+                    encoder_budget,
+                    max_mm_items_per_batch,
+                    dummy_modality,
+                )
 
                 # Create dummy batch of multimodal inputs.
                 batched_dummy_mm_inputs = self._get_mm_dummy_batch(
-                dummy_data_modality, max_num_mm_items)
+                    dummy_modality,
+                    max_mm_items_per_batch,
+                )
 
                 # Run multimodal encoder.
                 # Isolate encoder graph from post-processing to minimize
@@ -1583,15 +1573,14 @@ class TPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
                     "Multimodal Encoder profiling finished in in %.2f [secs].",
                     end - start)
 
-            assert len(dummy_encoder_outputs) == max_num_mm_items, (
+                sanity_check_mm_encoder_outputs(
-                "Expected dimension 0 of encoder outputs to match the number "
+                    dummy_encoder_outputs,
-                f"of multimodal data items: {max_num_mm_items}, got "
+                    expected_num_items=max_mm_items_per_batch,
-                f"{len(dummy_encoder_outputs)=} instead. This is most likely "
+                )
-                "due to the 'get_multimodal_embeddings' method of the model "
-                "not implemented correctly.")
 
                 # Cache the dummy encoder outputs.
-            self.encoder_cache["tmp"] = dict(enumerate(dummy_encoder_outputs))
+                self.encoder_cache["tmp"] = dict(
+                    enumerate(dummy_encoder_outputs))
 
         # Trigger compilation for general shape.
         self._dummy_run(num_tokens, self.num_reqs_max_model_len,
@@ -1809,33 +1798,25 @@ class TPUModelRunner(LoRAModelRunnerMixin, KVConnectorModelRunnerMixin):
             self.grammar_bitmask_cpu[:num_reqs].to(logits.device), \
             self.structured_decode_arange.to(logits.device)
 
-    def _get_mm_dummy_batch(self, modality: str,
+    def _get_mm_dummy_batch(
-                            batch_size: int) -> BatchedTensorInputs:
+        self,
-        # Dummy data for pre-compiling multimodal models.
+        modality: str,
-        dummy_request_data = self.mm_registry.get_decoder_dummy_data(
+        max_items_per_batch: int,
+    ) -> BatchedTensorInputs:
+        """Dummy data for profiling and precompiling multimodal models."""
+        dummy_decoder_data = self.mm_registry.get_decoder_dummy_data(
             model_config=self.model_config,
             seq_len=self.max_num_tokens,
+            mm_counts={modality: 1},
         )
-        dummy_mm_data = dummy_request_data.multi_modal_data
+        dummy_mm_data = dummy_decoder_data.multi_modal_data
 
-        # Dummy data definition in V0 may contain multiple multimodal items
+        # Result in the maximum GPU consumption of the model
-        # (e.g, multiple images) for a single request, therefore here we
-        # always replicate first item by max_num_mm_items times since in V1
-        # they are scheduled to be processed separately.
-        assert isinstance(dummy_mm_data, MultiModalKwargs), (
-            "Expected dummy multimodal data to be of type "
-            f"MultiModalKwargs, got {type(dummy_mm_data)=} instead. "
-            "This is most likely due to the model not having a merged "
-            "processor.")
-
-        # When models have a merged processor, their dummy data is
-        # already batched `MultiModalKwargs`, therefore we take the first
-        # `MultiModalKwargsItem` from the desired modality to profile on.
         dummy_mm_item = dummy_mm_data.get_item(modality=modality, item_index=0)
         dummy_mm_kwargs = MultiModalKwargs.from_items([dummy_mm_item])
 
         batched_dummy_mm_inputs = MultiModalKwargs.batch([dummy_mm_kwargs] *
-                                                         batch_size)
+                                                         max_items_per_batch)
         return MultiModalKwargs.as_kwargs(
             batched_dummy_mm_inputs,
             device=self.device,

vllm/v1/worker/utils.py

@@ -5,14 +5,123 @@ from typing import TYPE_CHECKING, Optional
 
 import torch
 
+from vllm.config import ModelConfig, SchedulerConfig
 from vllm.model_executor.models.interfaces import MultiModalEmbeddings
 from vllm.model_executor.models.utils import extract_layer_index
+from vllm.multimodal.registry import MultiModalRegistry
+from vllm.v1.core.encoder_cache_manager import compute_encoder_budget
 from vllm.v1.kv_cache_interface import KVCacheGroupSpec
 
 if TYPE_CHECKING:
     from vllm.attention.layer import Attention
 
 
+class MultiModalBudget:
+    """Helper class to calculate budget information for multi-modal models."""
+
+    def __init__(
+        self,
+        model_config: ModelConfig,
+        scheduler_config: SchedulerConfig,
+        mm_registry: MultiModalRegistry,
+        *,
+        max_model_len: int,
+        max_num_reqs: int,
+    ) -> None:
+        super().__init__()
+
+        self.model_config = model_config
+        self.scheduler_config = scheduler_config
+        self.mm_registry = mm_registry
+
+        encoder_compute_budget, encoder_cache_size = compute_encoder_budget(
+            model_config=model_config,
+            scheduler_config=scheduler_config,
+            mm_registry=mm_registry,
+        )
+
+        self.max_num_encoder_input_tokens = encoder_compute_budget
+        self.encoder_cache_size = encoder_cache_size
+        self.max_model_len = max_model_len
+        self.max_num_reqs = max_num_reqs
+
+        self.mm_limits = mm_registry.get_mm_limits_per_prompt(model_config)
+
+        max_items_per_prompt_by_modality = dict[str, int]()
+        max_items_per_batch_by_modality = dict[str, int]()
+
+        max_tokens_by_modality = mm_registry \
+            .get_max_tokens_per_item_by_nonzero_modality(model_config)
+
+        for modality, max_tokens in max_tokens_by_modality.items():
+            (
+                max_items_per_prompt,
+                max_items_per_batch,
+            ) = self.get_max_items(modality, max_tokens)
+
+            max_items_per_prompt_by_modality[modality] = max_items_per_prompt
+            max_items_per_batch_by_modality[modality] = max_items_per_batch
+
+        self.max_tokens_by_modality = max_tokens_by_modality
+        self.max_items_per_prompt_by_modality = max_items_per_prompt_by_modality
+        self.max_items_per_batch_by_modality = max_items_per_batch_by_modality
+
+    def get_modality_with_max_tokens(self) -> tuple[str, int]:
+        max_tokens_by_modality = self.max_tokens_by_modality
+        modality, max_tokens = max(max_tokens_by_modality.items(),
+                                   key=lambda item: item[1])
+
+        return modality, max_tokens
+
+    def get_encoder_budget(self) -> int:
+        return min(self.max_num_encoder_input_tokens, self.encoder_cache_size)
+
+    def get_max_items(
+        self,
+        modality: str,
+        max_tokens_per_item: int,
+    ) -> tuple[int, int]:
+        if max_tokens_per_item == 0:
+            return 0, 0
+
+        # Check how many items of this modality can be supported by
+        # the encoder budget.
+        encoder_budget = self.get_encoder_budget()
+
+        # TODO: handle encoder-decoder models once we support them.
+        if encoder_budget == 0:
+            return 0, 0
+
+        max_encoder_items_per_batch = encoder_budget // max_tokens_per_item
+
+        # Check how many items of this modality can be supported by
+        # the decoder budget.
+        mm_limit = self.mm_limits[modality]
+
+        max_items_per_prompt = max(
+            1,
+            min(mm_limit, self.max_model_len // max_tokens_per_item),
+        )
+
+        scheduler_config = self.scheduler_config
+        max_num_reqs = self.max_num_reqs
+
+        if not scheduler_config.enable_chunked_prefill:
+            max_num_reqs = min(
+                max_num_reqs,
+                scheduler_config.max_num_batched_tokens // max_tokens_per_item,
+            )
+
+        max_decoder_items_per_batch = max_num_reqs * max_items_per_prompt
+
+        max_items_per_batch = max(
+            1,
+            min(max_encoder_items_per_batch, max_decoder_items_per_batch),
+        )
+
+        return max_items_per_prompt, max_items_per_batch
+
+
 def sanity_check_mm_encoder_outputs(
     mm_embeddings: MultiModalEmbeddings,
     expected_num_items: int,