LMCache

LMCache

Making Long-Context LLM Inference 10x Faster and 10x Cheaper

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LMCache is a serving engine extension designed to reduce time to first token (TTFT) and increase throughput, particularly in long-context scenarios. It stores key-value caches of reusable texts across different locations like GPU, CPU DRAM, and Local Disk, allowing the reuse of any text in any serving engine instance. By combining LMCache with vLLM, significant delay savings and GPU cycle reduction are achieved in various large language model (LLM) use cases, such as multi-round question answering and retrieval-augmented generation (RAG). LMCache provides integration with the latest vLLM version, offering both online serving and offline inference capabilities. It supports sharing key-value caches across multiple vLLM instances and aims to provide stable support for non-prefix key-value caches along with user and developer documentation.

README:

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πŸ’‘ What is LMCache?

LMCache is a LLM serving engine extension to reduce TTFT and increase throughput, especially under long-context scenarios. By storing the KV caches of reusable texts across various locations including (GPU, CPU DRAM, Local Disk), LMCache reuse the KV caches of any reused text (not necessarily prefix) in any serving engine instance. Thus, LMCache saves precious GPU cycles and reduces response delay for users.

By combining LMCache with vLLM, LMCaches achieves 3-10x delay savings and GPU cycle reduction in many LLM use cases, including multi-round QA and RAG.

Try LMCache with pre-built vllm docker images here.

πŸš€ Performance snapshot

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πŸ’» Quickstart

LMCache provides the integration to the latest vLLM (0.6.2). To install LMCache, use the following command:

# requires python >= 3.10 and nvcc >= 12.1
pip install lmcache lmcache_vllm

LMCache has the same interface as vLLM (both online serving and offline inference). To use the online serving, you can start an OpenAI API-compatible vLLM server with LMCache via:

lmcache_vllm serve lmsys/longchat-7b-16k --gpu-memory-utilization 0.8

To use vLLM's offline inference with LMCache, just simply add lmcache_vllm before the import to vLLM components. For example

import lmcache_vllm.vllm as vllm
from lmcache_vllm.vllm import LLM 

More detailed documentation will be available soon.

- Sharing KV cache across multiple vLLM instances

LMCache supports sharing KV across different vLLM instances by the lmcache.server module. Here is a quick guide:

# Start lmcache server
lmcache_server localhost 65432

Then, start two vLLM instances with the LMCache config file

wget https://raw.githubusercontent.com/LMCache/LMCache/refs/heads/dev/examples/example.yaml

# start the first vLLM instance
LMCACHE_CONFIG_FILE=example.yaml CUDA_VISIBLE_DEVICES=0 lmcache_vllm serve lmsys/longchat-7b-16k --gpu-memory-utilization 0.8 --port 8000

# start the second vLLM instance
LMCACHE_CONFIG_FILE=example.yaml CUDA_VISIBLE_DEVICES=1 lmcache_vllm serve lmsys/longchat-7b-16k --gpu-memory-utilization 0.8 --port 8001

- What's next

We also provide multiple docker-based demos at πŸ”—LMCache-demos repo. The demos cover the following use cases:

Interested in Connecting?

Fill out the interest form and our team will reach out to you! https://forms.gle/mQfQDUXbKfp2St1z7

πŸ›£οΈ Incoming Milestones

  • [x] First release of LMCache
  • [x] Support installation through pip install and integrate with latest vLLM
  • [ ] Stable support for non-prefix KV caches
  • [ ] User and developer documentation

πŸ“– Blogs and documentations

Our blog posts and documentations are available online

Community meeting

Citation

If you use LMCache for your research, please cite our papers:

@inproceedings{liu2024cachegen,
  title={Cachegen: Kv cache compression and streaming for fast large language model serving},
  author={Liu, Yuhan and Li, Hanchen and Cheng, Yihua and Ray, Siddhant and Huang, Yuyang and Zhang, Qizheng and Du, Kuntai and Yao, Jiayi and Lu, Shan and Ananthanarayanan, Ganesh and others},
  booktitle={Proceedings of the ACM SIGCOMM 2024 Conference},
  pages={38--56},
  year={2024}
}

@article{cheng2024large,
  title={Do Large Language Models Need a Content Delivery Network?},
  author={Cheng, Yihua and Du, Kuntai and Yao, Jiayi and Jiang, Junchen},
  journal={arXiv preprint arXiv:2409.13761},
  year={2024}
}

@article{yao2024cacheblend,
  title={CacheBlend: Fast Large Language Model Serving with Cached Knowledge Fusion},
  author={Yao, Jiayi and Li, Hanchen and Liu, Yuhan and Ray, Siddhant and Cheng, Yihua and Zhang, Qizheng and Du, Kuntai and Lu, Shan and Jiang, Junchen},
  journal={arXiv preprint arXiv:2405.16444},
  year={2024}
}

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