Break the Sequential Dependency of LLM Inference Using Lookahead Decoding

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Introduction

We introduce Lookahead Decoding,

Contents

• Introduction
• Contents
• Installation
  • Install From The Source
  • Inference
  • Use In Your Own Code
• Citation
• Guidance

Installation

Install from the source

git clone https://github.com/hao-ai-lab/LookaheadDecoding.git
cd LookaheadDecoding
pip install -r requirements.txt
pip install -e .

Inference With Lookahead decoding

You can run the minimal example to see the speedup that Lookahead decoding brings.

python minimal.py #no Lookahead decoding
USE_LADE=1 LOAD_LADE=1 python minimal.py #use Lookahead decoding, 1.6x speedup

You can also enjoy chatting with your own chatbots with Lookahead decoding.

USE_LADE=1 python applications/chatbot.py  --model_path meta-llama/Llama-2-7b-chat-hf --debug --chat #chat, with lookahead 
USE_LADE=0 python applications/chatbot.py  --model_path meta-llama/Llama-2-7b-chat-hf --debug --chat #chat, without lookahead


USE_LADE=1 python applications/chatbot.py  --model_path meta-llama/Llama-2-7b-chat-hf --debug #no chat, with lookahead
USE_LADE=0 python applications/chatbot.py  --model_path meta-llama/Llama-2-7b-chat-hf --debug #no chat, without lookahead

Use Lookahead decoding in your own code

You can import and use Lookahead decoding in your own code in three LoCs. You also need to set USE_LADE=1 in command line or set os.environ["USE_LADE"]="1" in Python script. Note that Lookahead decoding only support LLaMA and Greedy Search yet.

import lade
lade.augment_all()
lade.config_pading(LEVEL=5, WINDOW_SIZE=7, GUESS_SET_SIZE=7, DEBUG=0)

Citation

@misc{fu2023lookahead,
    title = {Breaking the Sequential Dependency of LLM Inference Using Lookahead Decoding},
    url = {https://lmsys.org/blog/2023-11-21-lookahead-decoding/},
    author = {Yichao Fu and Peter Bailis and Ion Stoica and Hao Zhang},
    month = {November},
    year = {2023}
}

Guidance

The core implementation is in decoding.py. Lookahead decoding requires an adaptation for each specific model. An example is in models/llama.py.