We host regular meetups in San Francisco Bay Area every 2 months. We will share the project updates from the vLLM team and have guest speakers from the industry to share their experience and insights. Please find the materials of our previous meetups below:
-[vLLM Shanghai Meetup](https://mp.weixin.qq.com/s/pDmAXHcN7Iqc8sUKgJgGtg), August 23rd 2025. [[Slides]](https://drive.google.com/drive/folders/1OvLx39wnCGy_WKq8SiVKf7YcxxYI3WCH)
-[vLLM Korea Meetup](https://luma.com/cgcgprmh), August 19th 2025. [[Slides]](https://drive.google.com/file/d/1bcrrAE1rxUgx0mjIeOWT6hNe2RefC5Hm/view).
-[vLLM Beijing Meetup](https://mp.weixin.qq.com/s/dgkWg1WFpWGO2jCdTqQHxA), August 2nd 2025. [[Slides]](https://drive.google.com/drive/folders/1Pid6NSFLU43DZRi0EaTcPgXsAzDvbBqF)[[Recording]](https://www.chaspark.com/#/live/1166916873711665152).
-[NYC vLLM Meetup](https://lu.ma/c1rqyf1f), May 7th, 2025. [[Slides]](https://docs.google.com/presentation/d/1_q_aW_ioMJWUImf1s1YM-ZhjXz8cUeL0IJvaquOYBeA/edit?usp=sharing)
-[Asia Developer Day](https://www.sginnovate.com/event/limited-availability-morning-evening-slots-remaining-inaugural-vllm-asia-developer-day), April 3rd 2025. [[Slides]](https://docs.google.com/presentation/d/19cp6Qu8u48ihB91A064XfaXruNYiBOUKrBxAmDOllOo/edit?usp=sharing).
If you run out of CPU RAM, try the following options:
- (Multi-modal models only) you can set the size of multi-modal processor cache by setting `mm_processor_cache_gb` engine argument (default 4 GiB per API process + 4 GiB per engine core process)
- (Multi-modal models only) you can set the size of multi-modal cache by setting `mm_processor_cache_gb` engine argument (default 4 GiB).
- (CPU backend only) you can set the size of KV cache using `VLLM_CPU_KVCACHE_SPACE` environment variable (default 4 GiB).
@@ -48,7 +48,7 @@ You can tune the performance by adjusting `max_num_batched_tokens`:
- Smaller values (e.g., 2048) achieve better inter-token latency (ITL) because there are fewer prefills slowing down decodes.
- Higher values achieve better time to first token (TTFT) as you can process more prefill tokens in a batch.
- For optimal throughput, we recommend setting `max_num_batched_tokens > 8096` especially for smaller models on large GPUs.
- For optimal throughput, we recommend setting `max_num_batched_tokens > 8192` especially for smaller models on large GPUs.
- If `max_num_batched_tokens` is the same as `max_model_len`, that's almost the equivalent to the V0 default scheduling policy (except that it still prioritizes decodes).
```python
...
...
@@ -129,6 +129,56 @@ Data parallelism replicates the entire model across multiple GPU sets and proces
Data parallelism can be combined with the other parallelism strategies and is set by `data_parallel_size=N`.
Note that MoE layers will be sharded according to the product of the tensor parallel size and data parallel size.
### Batch-level DP for Multi-Modal Encoders
By default, TP is used to shard the weights of multi-modal encoders just like for language decoders,
in order to reduce the memory and compute load on each GPU.
However, since the size of multi-modal encoders is very small compared to language decoders,
there is relatively little gain from TP. On the other hand, TP incurs significant communication
overhead because of all-reduce being performed after every layer.
Given this, it may be advantageous to instead shard the batched input data using TP, essentially
performing batch-level DP. This has been shown to improve the throughput by around 10% for
`tensor_parallel_size=8`. For vision encoders that use hardware-unoptimized Conv3D operations,
batch-level DP can provide another 40% increase to throughput compared to regular TP.
Nevertheless, since the weights of the multi-modal encoder are replicated across each TP rank,
there will be a minor increase in memory consumption and may cause OOM if you can barely fit the model already.
You can enable batch-level DP by setting `mm_encoder_tp_mode="data"`, for example:
```python
fromvllmimportLLM
llm=LLM(
model="Qwen/Qwen2.5-VL-72B-Instruct",
tensor_parallel_size=4,
# When mm_encoder_tp_mode="data",
# the vision encoder uses TP=4 (not DP=1) to shard the input data,
# so the TP size becomes the effective DP size.
# Note that this is independent of the DP size for language decoder which is used in expert parallel setting.
mm_encoder_tp_mode="data",
# The language decoder uses TP=4 to shard the weights regardless
# of the setting of mm_encoder_tp_mode
)
```
!!! important
Batch-level DP is not to be confused with API request-level DP
(which is instead controlled by `data_parallel_size`).
Batch-level DP needs to be implemented on a per-model basis,
and enabled by setting `supports_encoder_tp_data = True` in the model class.
Regardless, you need to set `mm_encoder_tp_mode="data"` in engine arguments to use this feature.
Known supported models:
- Llama4 (<gh-pr:18368>)
- MiniCPM-V-2.5 or above (<gh-pr:23327>, <gh-pr:23948>)
If most of your requests are shorter than the maximum model length but you still need to accommodate occasional longer requests, setting a high maximum model length can negatively impact performance. In these cases, you can try introducing mostmodellen by specifying the `VLLM_TPU_MOST_MODEL_LEN` environment variable.
If most of your requests are shorter than the maximum model length but you still need to accommodate occasional longer requests, setting a high maximum model length can negatively impact performance. In these cases, you can try introducing most-model-len by specifying the `VLLM_TPU_MOST_MODEL_LEN` environment variable.
For example, 1% requests are 32k length and 99% requests are 2k length. You can pass 32k into `--max-model-len 32768` and use `VLLM_TPU_MOST_MODEL_LEN=2048`.
The requests get subdivided into max-model-len and most-model-len categories, for the latter category, we can gain better performance since the server can process more requests at a time.
The requests get subdivided into max-model-len and most-model-len categories, for the latter category, you can gain better performance since the server can process more requests at a time.
#### Padding
For online serving with latency requirements, consider switching to bucket padding by setting the `VLLM_TPU_BUCKET_PADDING_GAP` environment variable. Because of the layout of the TPU, try using increments of 128: 128, 256, etc.
For online serving with latency requirements, consider switching to bucket padding by setting the `VLLM_TPU_BUCKET_PADDING_GAP` environment variable. Because of the layout of the TPU, try using increments of 128 (e.g., 128, 256, etc.)
The server pads the requests into fixed lengths before sending them to the model to avoid recompilation. To read more about tpu padding, see [here](https://cloud.google.com/tpu/docs/performance-guide#xla-efficiencies). Currently, there are 2 ways to pad the requests:
The server pads the requests into fixed lengths before sending them to the model to avoid recompilation. To read more about TPU padding, see [here](https://cloud.google.com/tpu/docs/performance-guide#xla-efficiencies). Currently, there are 2 ways to pad the requests:
1) the default exponential padding (pad to the nearest power of 2)
2) bucket padding (pad to the nearest linearly increasing bucket).
1. the default exponential padding (pad to the nearest power of 2)
2. bucket padding (pad to the nearest linearly increasing bucket).
When using bucket padding, the buckets start from 16, end at max_model_len, and increment by `VLLM_TPU_BUCKET_PADDING_GAP`.
For example, max_model_len=512, padding_gap=64, the buckets will be [16, 32, 64, 128, 192, 256, 320, 384, 448, 512].
The fewer tokens we pad, the less unnecessary computation TPU does, the better performance we can get. For example, if num_tokens=300, with exponential padding, we pad to 512, with the bucket_padding above, we pad to 320.
The fewer tokens you pad, the less unnecessary computation TPU does, the better performance you can get. For example, if num_tokens=300, with exponential padding, you pad to 512, with the bucket_padding above, you pad to 320.
However, you need to be careful to choose the padding gap. If the gap is too small, it means the number of buckets is large, leading to increased warmup (precompile) time and higher memory to store the compiled graph. Too many compilaed graphs may lead to HBM OOM. Conversely, an overly large gap yields no performance improvement compared to the default exponential padding.
However, you need to be careful to choose the padding gap. If the gap is too small, it means the number of buckets is large, leading to increased warmup (precompile) time and higher memory to store the compiled graph. Too many compiled graphs may lead to HBM OOM. Conversely, an overly large gap yields no performance improvement compared to the default exponential padding.
@@ -121,3 +121,31 @@ To support a model with interleaving sliding windows, we need to take care of th
- In the modeling code, parse the correct sliding window value for every layer, and pass it to the attention layer's `per_layer_sliding_window` argument. For reference, check [this line](https://github.com/vllm-project/vllm/blob/996357e4808ca5eab97d4c97c7d25b3073f46aab/vllm/model_executor/models/llama.py#L171).
With these two steps, interleave sliding windows should work with the model.
### How to support models that use Mamba?
We consider 3 different scenarios:
1. Models that use Mamba layers (either Mamba-1 or Mamba-2) but do not use attention layers.
2. Models that combine Mamba layers (either Mamba-1 or Mamba-2) together with attention layers.
3. Models that combine Mamba-like mechanisms (e.g., Linear Attention, ShortConv) together with attention layers.
For case (1), we recommend looking at the implementation of [`MambaForCausalLM`](gh-file:vllm/model_executor/models/mamba.py)(for Mamba-1) or [`Mamba2ForCausalLM`](gh-file:vllm/model_executor/models/mamba2.py)(for Mamba-2) as a reference.
The model should inherit protocol `IsAttentionFree` and also implement class methods `get_mamba_state_dtype_from_config` and `get_mamba_state_shape_from_config` to calculate the state shapes and data types from the config.
For the mamba layers themselves, please use the [`MambaMixer`](gh-file:vllm/model_executor/layers/mamba/mamba_mixer.py)(for Mamba-1) or [`MambaMixer2`](gh-file:vllm/model_executor/layers/mamba/mamba_mixer2.py)(for Mamba-2) classes.
Please *do not* use the `MambaCacheManager` (deprecated in V1) or replicate any of the V0-specific code paths in the existing model implementations.
V0-only classes and code will be removed in the very near future.
The model should also be added to the `MODELS_CONFIG_MAP` dictionary in <gh-file:vllm/model_executor/models/config.py> to ensure that the runtime defaults are optimized.
For case (2), we recommend using as a reference the implementation of [`JambaForCausalLM`](gh-file:vllm/model_executor/models/jamba.py)(for an example of a model that uses Mamba-1 and attention together) or [`BambaForCausalLM`](gh-file:vllm/model_executor/models/bamba.py)(for an example of a model that uses Mamba-2 and attention together).
These models should follow the same instructions as case (1), but they should inherit protocol `IsHybrid` (instead of `IsAttentionFree`) and it is *not* necessary to add them to the `MODELS_CONFIG_MAP` (their runtime defaults will be inferred from the protocol).
For case (3), we recommend looking at the implementation of [`MiniMaxText01ForCausalLM`](gh-file:vllm/model_executor/models/minimax_text_01.py) or [`Lfm2ForCausalLM`](gh-file:vllm/model_executor/models/lfm2.py) as a reference, which use custom "mamba-like" layers `MiniMaxText01LinearAttention` and `ShortConv` respectively.
Please follow the same guidelines as case (2) for implementing these models.
We use "mamba-like" to refer to layers that posses a state that is updated in-place, rather than being appended-to (like KV cache for attention).
For implementing new custom mamba-like layers, one should inherit from `MambaBase` and implement the methods `get_state_dtype`, `get_state_shape` to calculate the data types and state shapes at runtime, as well as `mamba_type` and `get_attn_backend`.
It is also necessary to implement the "attention meta-data" class which handles the meta-data that is common across all layers.
Please see [`LinearAttentionMetadata`](gh-file:vllm/v1/attention/backends/linear_attn.py) or [`ShortConvAttentionMetadata`](gh-file:v1/attention/backends/short_conv_attn.py) for examples of this.
Finally, if one wants to support torch compile and CUDA graphs, it necessary to wrap the call to the mamba-like layer inside a custom op and register it.
Please see the calls to `direct_register_custom_op` in <gh-file:vllm/model_executor/models/minimax_text_01.py> or <gh-file:vllm/model_executor/layers/mamba/short_conv.py> for examples of this.
The new custom op should then be added to the list `_attention_ops` in <gh-file:vllm/config/compilation.py> to ensure that piecewise CUDA graphs works as intended.
@@ -629,7 +629,7 @@ Each [PromptUpdate][vllm.multimodal.processing.PromptUpdate] instance specifies
self,
mm_items: MultiModalDataItems,
hf_processor_mm_kwargs: Mapping[str, object],
out_mm_kwargs: MultiModalKwargs,
out_mm_kwargs: MultiModalKwargsItems,
) -> Sequence[PromptUpdate]:
hf_config = self.info.get_hf_config()
image_token_id = hf_config.image_token_index
...
...
@@ -778,7 +778,7 @@ Each [PromptUpdate][vllm.multimodal.processing.PromptUpdate] instance specifies
self,
mm_items: MultiModalDataItems,
hf_processor_mm_kwargs: Mapping[str, object],
out_mm_kwargs: MultiModalKwargs,
out_mm_kwargs: MultiModalKwargsItems,
) -> Sequence[PromptUpdate]:
hf_config = self.info.get_hf_config()
bos_token_id = hf_config.bos_token_id
...
...
@@ -855,7 +855,7 @@ Examples:
### Custom HF processor
Some models don't define a HF processor class on HF Hub. In that case, you can define a custom HF processor that has the same call signature as HF processors and pass it to [_call_hf_processor][vllm.multimodal.processing.BaseMultiModalProcessor._call_hf_processor].
Some models don't define an HF processor class on HF Hub. In that case, you can define a custom HF processor that has the same call signature as HF processors and pass it to [_call_hf_processor][vllm.multimodal.processing.BaseMultiModalProcessor._call_hf_processor].
If the startup or readiness probe failureThreshold is too low for the time needed to startup the server, Kubernetes scheduler will kill the container. A couple of indications that this has happened:
If the startup or readiness probe failureThreshold is too low for the time needed to startup the server, Kubernetes scheduler will kill the container. A couple of indications that this has happened:
@@ -133,12 +133,12 @@ class FusedMoEModularKernel:
Typically a FusedMoEPrepareAndFinalize type is backed by an All2All Dispatch & Combine implementation / kernel. For example,
* PplxPrepareAndFinalize type is backed by Pplx All2All kernels,
* DeepEPHTPrepareAndFinalize type is backed by DeepEP High-Throughtput All2All kernels, and
* DeepEPHTPrepareAndFinalize type is backed by DeepEP High-Throughput All2All kernels, and
* DeepEPLLPrepareAndFinalize type is backed by DeepEP Low-Latency All2All kernels.
#### Step 1: Add an All2All manager
The purpose of the All2All Manager is to setup the All2All kernel implementations. The `FusedMoEPrepareAndFinalize` implementations typically fetch a kernel-implementation "handle" from the All2All Manager to invoke the Dispatch and Combine functions. Please look at the All2All Manager implementations [here](gh-file:vllm/distributed/device_communicators/all2all.py).
The purpose of the All2All Manager is to setup the All2All kernel implementations. The `FusedMoEPrepareAndFinalize` implementations typically fetch a kernel-implementation "handle" from the All2All Manager to invoke the Dispatch and Combine functions. Please look at the All2All Manager implementations [here](gh-file:vllm/distributed/device_communicators/all2all.py).
#### Step 2: Add a FusedMoEPrepareAndFinalize Type
...
...
@@ -183,7 +183,7 @@ implementations that input `FusedMoEActivationFormat.Standard` support chunking
#### maybe_make_prepare_finalize
The `maybe_make_prepare_finalize` method is responsbile for constructing an instance of `FusedMoEPrepareAndFinalize` when appropriate based on the current all2all backend, e.g. when EP + DP is enabled. The base class method currently constructs all the `FusedMoEPrepareAndFinalize` objects for the EP+DP case. Derived classes can override this method to construct prepare/finalize objects for different scenarios, e.g. `ModelOptNvFp4FusedMoE` can construct a `FlashInferCutlassMoEPrepareAndFinalize` for the EP+TP case.
The `maybe_make_prepare_finalize` method is responsible for constructing an instance of `FusedMoEPrepareAndFinalize` when appropriate based on the current all2all backend, e.g. when EP + DP is enabled. The base class method currently constructs all the `FusedMoEPrepareAndFinalize` objects for the EP+DP case. Derived classes can override this method to construct prepare/finalize objects for different scenarios, e.g. `ModelOptNvFp4FusedMoE` can construct a `FlashInferCutlassMoEPrepareAndFinalize` for the EP+TP case.
Please refer to the implementations in,
*`ModelOptNvFp4FusedMoE`
...
...
@@ -198,7 +198,7 @@ Please refer to the implementations in,
*`CompressedTensorsW8A8Fp8MoECutlassMethod`
*`Fp8MoEMethod`
*`ModelOptNvFp4FusedMoE`
dervied classes.
derived classes.
#### init_prepare_finalize
...
...
@@ -226,7 +226,7 @@ Doing this will add the new implementation to the test suite.
The unit test file [test_modular_kernel_combinations.py](gh-file:tests/kernels/moe/test_modular_kernel_combinations.py) can also be executed as a standalone script.