library_name: pytorch
license: llama3
pipeline_tag: text-generation
tags:
- llm
- generative_ai
- quantized
- android
Llama-v3-8B-Chat: Optimized for Mobile Deployment
State-of-the-art large language model useful on a variety of language understanding and generation tasks
Llama 3 is a family of LLMs. The "Chat" at the end indicates that the model is optimized for chatbot-like dialogue. The model is quantized to w4a16(4-bit weights and 16-bit activations) and part of the model is quantized to w8a16(8-bit weights and 16-bit activations) making it suitable for on-device deployment. For Prompt and output length specified below, the time to first token is Llama-PromptProcessor-Quantized's latency and average time per addition token is Llama-TokenGenerator-KVCache-Quantized's latency.
This model is an implementation of Llama-v3-8B-Chat found here. This repository provides scripts to run Llama-v3-8B-Chat on Qualcomm® devices. More details on model performance across various devices, can be found here.
Model Details
- Model Type: Text generation
- Model Stats:
- Number of parameters: 8B
- Precision: w4a16 + w8a16 (few layers)
- Num of key-value heads: 8
- Model-1 (Prompt Processor): Llama-PromptProcessor-Quantized
- Max context length: 1024
- Prompt processor model size: 4.8GB
- Prompt processor input: 1024 tokens
- Prompt processor output: 1024 output tokens + KVCache for token generator
- Model-2 (Token Generator): Llama-TokenGenerator-KVCache-Quantized
- Token generator model size: 4.8GB
- Token generator input: 1 input token + past KVCache
- Token generator output: 1 output token + KVCache for next iteration
- Decoding length: 1024 (1 output token + 1023 from KVCache)
- Use: Initiate conversation with prompt-processor and then token generator for subsequent iterations.
Deploying Llama 3 on-device
Large Language Model (LLM) such as Llama 2 has the following complexities to deploy on-device:
- Model size is too large to fit in device memory for inference
- Multi-Head Attention (MHA) has large activations leading to fallback from accelerators
- High model load and inference time
We can tackle the above constraints with the following steps:
- Quantize weights to reduce on-disk model size, e.g., int8 or int4 weights
- Quantize activations to reduce inference time memory pressure
- Graph transformations to reduce inference time memory pressure, e.g., Multi-Head to Split-Head Attention (MHA -> SHA)
- Graph transformations to convert or decompose operations into more accelerator friendly operations e.g. Linear to Conv
- For LLM with 7B or more parameters, above steps are still not good enough on mobile, hence we go one step further and split model into sub-parts.
Here, we divide the model into 4 parts in order to
- Make model exportable with low memory usage
- Avoid inference time out-of-memory errors
In order to export Llama 3, please ensure
- Host machine has >40GB memory (RAM+swap-space)
- If you don't have enough memory, export.py will dump instructions to increase swap space accordingly
Sample output prompts generated on-device
- --prompt "where is California?"
------- Response Summary --------
Prompt: where is California?
Response: California is a state located on the West Coast of
- --prompt "what is 2+3?" --max-output-tokens 30
-------- Response Summary --------
Prompt: what is 2+3?
Response: 2 + 3 = 5
- --prompt "what is superposition in Quantum Physics?" --max-output-tokens 30
Prompt: what is superposition in Quantum Physics?
Response: Superposition is a fundamental concept in quantum mechanics, which is a branch of physics that studies the behavior of matter and energy at a very
Device | Chipset | Target Runtime | Inference Time (ms) | Peak Memory Range (MB) | Precision | Primary Compute Unit | Target Model |
---|---|---|---|---|---|---|---|
Samsung Galaxy S23 Ultra (Android 13) | Snapdragon® 8 Gen 2 | QNN Model Library | 72.856 ms | 1 - 1261 MB | UINT16 | NPU | Llama3-TokenGenerator-KVCache-Quantized |
Samsung Galaxy S23 Ultra (Android 13) | Snapdragon® 8 Gen 2 | QNN Model Library | 1316.502 ms | 0 - 979 MB | UINT16 | NPU | Llama3-PromptProcessor-Quantized |
Installation
This model can be installed as a Python package via pip.
pip install "qai-hub-models[llama_v3_8b_chat_quantized]"
Configure Qualcomm® AI Hub to run this model on a cloud-hosted device
Sign-in to Qualcomm® AI Hub with your
Qualcomm® ID. Once signed in navigate to Account -> Settings -> API Token
.
With this API token, you can configure your client to run models on the cloud hosted devices.
qai-hub configure --api_token API_TOKEN
Navigate to docs for more information.
Demo off target
The package contains a simple end-to-end demo that downloads pre-trained weights and runs this model on a sample input.
python -m qai_hub_models.models.llama_v3_8b_chat_quantized.demo
The above demo runs a reference implementation of pre-processing, model inference, and post processing.
NOTE: If you want running in a Jupyter Notebook or Google Colab like environment, please add the following to your cell (instead of the above).
%run -m qai_hub_models.models.llama_v3_8b_chat_quantized.demo
Run model on a cloud-hosted device
In addition to the demo, you can also run the model on a cloud-hosted Qualcomm® device. This script does the following:
- Performance check on-device on a cloud-hosted device
- Downloads compiled assets that can be deployed on-device for Android.
- Accuracy check between PyTorch and on-device outputs.
python -m qai_hub_models.models.llama_v3_8b_chat_quantized.export
Profile Job summary of Llama3-TokenGenerator-KVCache-Quantized
--------------------------------------------------
Device: Snapdragon X Elite CRD (11)
Estimated Inference Time: 79.17 ms
Estimated Peak Memory Range: 16.26-16.26 MB
Compute Units: NPU (20765) | Total (20765)
Profile Job summary of Llama3-PromptProcessor-Quantized
--------------------------------------------------
Device: Snapdragon X Elite CRD (11)
Estimated Inference Time: 1668.29 ms
Estimated Peak Memory Range: 10.30-10.30 MB
Compute Units: NPU (20248) | Total (20248)
Deploying compiled model to Android
The models can be deployed using multiple runtimes:
TensorFlow Lite (
.tflite
export): This tutorial provides a guide to deploy the .tflite model in an Android application.QNN (
.so
export ): This sample app provides instructions on how to use the.so
shared library in an Android application.
View on Qualcomm® AI Hub
Get more details on Llama-v3-8B-Chat's performance across various devices here. Explore all available models on Qualcomm® AI Hub
License
- The license for the original implementation of Llama-v3-8B-Chat can be found here.
- The license for the compiled assets for on-device deployment can be found here
References
Community
- Join our AI Hub Slack community to collaborate, post questions and learn more about on-device AI.
- For questions or feedback please reach out to us.