Files
xc-llm-ascend/examples/prompt_embed_inference.py
Song Zhixin 216fc0e8e4 [feature] Prompt Embeddings Support for v1 Engine (#3026)
### What this PR does / why we need it?
this PR based on
[19746](https://github.com/vllm-project/vllm/issues/19746), support
Prompt Embeddings for v1 engine on NPU

### Does this PR introduce _any_ user-facing change?

### How was this patch tested?

```python
python examples/prompt_embed_inference.py
```


- vLLM version: v0.11.0
- vLLM main:
https://github.com/vllm-project/vllm/commit/releases/v0.11.1

---------

Signed-off-by: jesse <szxfml@gmail.com>
2025-10-30 17:15:57 +08:00

98 lines
2.9 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""
Demonstrates how to generate prompt embeddings using
Hugging Face Transformers and use them as input to vLLM
for both single and batch inference.
Model: meta-llama/Llama-3.2-1B-Instruct
Note: This model is gated on Hugging Face Hub.
You must request access to use it:
https://huggingface.co/meta-llama/Llama-3.2-1B-Instruct
Requirements:
- vLLM
- transformers
Run:
python examples/prompt_embed_inference.py
"""
import torch
from transformers import AutoModelForCausalLM, AutoTokenizer, PreTrainedTokenizer
from vllm import LLM
def init_tokenizer_and_llm(model_name: str):
llm = LLM(model=model_name, enable_prompt_embeds=True)
tokenizer = AutoTokenizer.from_pretrained(model_name)
transformers_model = AutoModelForCausalLM.from_pretrained(model_name)
embedding_layer = transformers_model.get_input_embeddings()
return tokenizer, embedding_layer, llm
def get_prompt_embeds(
chat: list[dict[str, str]],
tokenizer: PreTrainedTokenizer,
embedding_layer: torch.nn.Module,
):
token_ids = tokenizer.apply_chat_template(
chat, add_generation_prompt=True, return_tensors="pt"
)
prompt_embeds = embedding_layer(token_ids).squeeze(0)
return prompt_embeds
def single_prompt_inference(
llm: LLM, tokenizer: PreTrainedTokenizer, embedding_layer: torch.nn.Module
):
chat = [{"role": "user", "content": "Please tell me about the capital of France."}]
prompt_embeds = get_prompt_embeds(chat, tokenizer, embedding_layer)
outputs = llm.generate(
{
"prompt_embeds": prompt_embeds,
}
)
print("\n[Single Inference Output]")
print("-" * 30)
for o in outputs:
print(o.outputs[0].text)
print("-" * 30)
def batch_prompt_inference(
llm: LLM, tokenizer: PreTrainedTokenizer, embedding_layer: torch.nn.Module
):
chats = [
[{"role": "user", "content": "Please tell me about the capital of France."}],
[{"role": "user", "content": "When is the day longest during the year?"}],
[{"role": "user", "content": "Where is bigger, the moon or the sun?"}],
]
prompt_embeds_list = [
get_prompt_embeds(chat, tokenizer, embedding_layer) for chat in chats
]
outputs = llm.generate([{"prompt_embeds": embeds} for embeds in prompt_embeds_list])
print("\n[Batch Inference Outputs]")
print("-" * 30)
for i, o in enumerate(outputs):
print(f"Q{i + 1}: {chats[i][0]['content']}")
print(f"A{i + 1}: {o.outputs[0].text}\n")
print("-" * 30)
def main():
model_name = "meta-llama/Llama-3.2-1B-Instruct"
tokenizer, embedding_layer, llm = init_tokenizer_and_llm(model_name)
single_prompt_inference(llm, tokenizer, embedding_layer)
batch_prompt_inference(llm, tokenizer, embedding_layer)
if __name__ == "__main__":
main()