Deploy Llama 2 7B on AWS inferentia2 with Amazon SageMaker

November 14, 202311 minute readView Code

In this end-to-end tutorial, you will learn how to deploy and speed up Llama 2 inference using AWS Inferentia2 and optimum-neuron on Amazon SageMaker. Optimum Neuron is the interface between the Hugging Face Transformers & Diffusers library and AWS Accelerators including AWS Trainium and AWS Inferentia2.

You will learn how to:

Convert Llama 2 to AWS Neuron (Inferentia2) with optimum-neuron
Create a custom inference.py script for Llama 2
Upload the neuron model and inference script to Amazon S3
Deploy a Real-time Inference Endpoint on Amazon SageMaker
Run inference and chat with Llama 2

Quick intro: AWS Inferentia 2

AWS inferentia (Inf2) are purpose-built EC2 for deep learning (DL) inference workloads. Inferentia 2 is the successor of AWS Inferentia, which promises to deliver up to 4x higher throughput and up to 10x lower latency.

instance size	accelerators	Neuron Cores	accelerator memory	vCPU	CPU Memory	on-demand price ($/h)
inf2.xlarge	1	2	32	4	16	0.76
inf2.8xlarge	1	2	32	32	128	1.97
inf2.24xlarge	6	12	192	96	384	6.49
inf2.48xlarge	12	24	384	192	768	12.98

Additionally, inferentia 2 will support the writing of custom operators in c++ and new datatypes, including FP8 (cFP8).

Let's get started! 🚀

If you are going to use Sagemaker in a local environment (not SageMaker Studio or Notebook Instances). You need access to an IAM Role with the required permissions for Sagemaker. You can find here more about it.

1. Convert Llama 2 to AWS Neuron (Inferentia2) with `optimum-neuron`

We are going to use the optimum-neuron to compile/convert our model to neuronx. Optimum Neuron provides a set of tools enabling easy model loading, training and inference on single- and multi-Accelerator settings for different downstream tasks.

As a first step, we need to install the optimum-neuron and other required packages.

Tip: If you are using Amazon SageMaker Notebook Instances or Studio you can go with the conda_python3 conda kernel.

# Install the required packages
%pip install "optimum-neuron==0.0.13" --upgrade
%pip install "sagemaker>=2.197.0"  --upgrade

After we have installed the optimum-neuron we can convert load and convert our model.

We are going to use the meta-llama/Llama-2-7b-chat-hf model. Llama 2 is a collection of pretrained and fine-tuned generative text models ranging in scale from 7 billion to 70 billion parameters. This is the repository for the 7B fine-tuned model, optimized for dialogue use cases.

At the time of writing, the AWS Inferentia2 does not support dynamic shapes for inference, which means that the we need to specify our image size in advanced for compiling and inference.

In simpler terms, this means we need to define the input shapes for our prompt (sequence length), batch size, height and width of the image.

We precompiled the model with the following parameters and pushed it to the Hugging Face Hub:

sequence_length: 2048
batch_size: 2
neuron: 2.15.0

Note: If you want to compile your own model or a different Llama 2 checkpoint you need to use ~120GB of memory and the compilation can take ~60 minutes. We used an inf2.24xlarge ec2 instance with the Hugging Face Neuron Deep Learning AMI to compile the model.

from huggingface_hub import snapshot_download
 
# compiled model id
compiled_model_id = "aws-neuron/Llama-2-7b-chat-hf-seqlen-2048-bs-2"
 
# save compiled model to local directory
save_directory = "llama_neuron"
# Downloads our compiled model from the HuggingFace Hub
# using the revision as neuron version reference
# and makes sure we exlcude the symlink files and "hidden" files, like .DS_Store, .gitignore, etc.
snapshot_download(compiled_model_id, revision="2.15.0", local_dir=save_directory, local_dir_use_symlinks=False, allow_patterns=["[!.]*.*"])
 
 
###############################################
# COMMENT IN BELOW TO COMPILE DIFFERENT MODEL #
###############################################
#
# from optimum.neuron import NeuronModelForCausalLM
# from transformers import AutoTokenizer
#
# # model id you want to compile
# vanilla_model_id = "meta-llama/Llama-2-7b-chat-hf"
#
# # configs for compiling model
# compiler_args = {"num_cores": 2, "auto_cast_type": "fp16"}
# input_shapes = {
#   "sequence_length": 2048, # max length to generate
#   "batch_size": 1 # batch size for the model
#   }
#
# llm = NeuronModelForCausalLM.from_pretrained(vanilla_model_id, export=True, **input_shapes, **compiler_args)
# tokenizer = AutoTokenizer.from_pretrained(model_id)
#
# # Save locally or upload to the HuggingFace Hub
# save_directory = "llama_neuron"
# llm.save_pretrained(save_directory)
# tokenizer.save_pretrained(save_directory)

2. Create a custom `inference.py` script for Llama 2 7B

The Hugging Face Inference Toolkit supports zero-code deployments on top of the pipeline feature from 🤗 Transformers. This allows users to deploy Hugging Face transformers without an inference script [Example].

Currently is this feature not supported with AWS Inferentia2, which means we need to provide an inference.py for running inference. But optimum-neuron has integrated support for the 🤗 Diffusers pipeline feature. That way we can use the optimum-neuron to create a pipeline for our model.

If you want to know more about the inference.py script check out this example. It explains amongst other things what the model_fn and predict_fn are.

# create code directory in our model directory
!mkdir {save_directory}/code

We are using the NEURON_RT_NUM_CORES=2 to make sure that each HTTP worker uses 2 Neuron core for inference. In additon we are going to use "templates for chat models" and new feature of transformers, which allows us to provide OpenAI messages, which are then converted to the correct input format for the model.

messages = [
    {"role": "user", "content": "Hi there!"},
    {"role": "assistant", "content": "Nice to meet you!"},
    {"role": "user", "content": "Can I ask a question?"}
]

For this to work we need jinja2 installed. Lets create a requirements.txt file and install the required packages.

%%writefile {save_directory}/code/requirements.txt
 
jinja2>="3.0.0"

Now, we create our inference.py file using the apply_chat_template method.

%%writefile {save_directory}/code/inference.py
import os
# To use two neuron core per worker
os.environ["NEURON_RT_NUM_CORES"] = "2"
import torch
import torch_neuronx
import base64
from io import BytesIO
from optimum.neuron import pipeline
 
def model_fn(model_dir):
    # load local converted model and tokenizer
    print("loading pipeline...")
    pipe = pipeline("text-generation", model_dir)
    print("loading complete")
    return pipe
 
 
def predict_fn(data, pipe):
    # extract prompt from data
    messages = data.pop("inputs", data)
    parameters = data.pop("parameters", None)
 
    # convert messages to input ids
    inputs = pipe.tokenizer.apply_chat_template(messages, add_generation_prompt=True,tokenize=False)
    # run generation
    if parameters is not None:
        outputs = pipe(inputs, **parameters)[0]
    else:
        outputs = pipe(inputs)[0]
 
    # decode generation
    return {"generation": outputs["generated_text"][len(inputs):].strip()}

3. Upload the neuron model and inference script to Amazon S3

Before we can deploy our neuron model to Amazon SageMaker we need to upload it all our model artifacts to Amazon S3.

Note: Currently inf2 instances are only available in the us-east-2 & us-east-1 region [REF]. Therefore we need to force the region to us-east-2.

Lets create our SageMaker session and upload our model to Amazon S3.

import sagemaker
import boto3
sess = sagemaker.Session()
# sagemaker session bucket -> used for uploading data, models and logs
# sagemaker will automatically create this bucket if it not exists
sagemaker_session_bucket=None
if sagemaker_session_bucket is None and sess is not None:
    # set to default bucket if a bucket name is not given
    sagemaker_session_bucket = sess.default_bucket()
 
try:
    role = sagemaker.get_execution_role()
except ValueError:
    iam = boto3.client('iam')
    role = iam.get_role(RoleName='sagemaker_execution_role')['Role']['Arn']
 
sess = sagemaker.Session(default_bucket=sagemaker_session_bucket)
 
print(f"sagemaker role arn: {role}")
print(f"sagemaker bucket: {sess.default_bucket()}")
print(f"sagemaker session region: {sess.boto_region_name}")
assert sess.boto_region_name in ["us-east-2", "us-east-1"] , "region must be us-east-2 or us-west-2, due to instance availability"

We create our model.tar.gz with our inference.py script.

Note: We will use pigz for multi-core compression to speed up the process. Make sure pigz is installed on your system, you can install it on ubuntu with sudo apt install pigz. With pigz and 32 cores compression takes ~2.4min

# create a model.tar.gz archive with all the model artifacts and the inference.py script.
%cd {save_directory}
!tar -cf model.tar.gz --use-compress-program=pigz *
%cd ..

Next, we upload our model.tar.gz to Amazon S3 using our session bucket and sagemaker sdk.

from sagemaker.s3 import S3Uploader
 
# create s3 uri
s3_model_path = f"s3://{sess.default_bucket()}/neuronx/llama"
 
# upload model.tar.gz
s3_model_uri = S3Uploader.upload(local_path=f"{save_directory}/model.tar.gz", desired_s3_uri=s3_model_path)
print(f"model artifcats uploaded to {s3_model_uri}")

4. Deploy a Real-time Inference Endpoint on Amazon SageMaker

After we have uploaded our model artifacts to Amazon S3 can we create a custom HuggingfaceModel. This class will be used to create and deploy our real-time inference endpoint on Amazon SageMaker.

The inf2.xlarge instance type is the smallest instance type with AWS Inferentia2 support. It comes with 1 Inferentia2 chip with 2 Neuron Cores. This means we can use 2 Neuron Cores to minimize latency for our image generation.

import time
from sagemaker.huggingface.model import HuggingFaceModel
 
# create Hugging Face Model Class
huggingface_model = HuggingFaceModel(
   model_data=s3_model_uri,        # path to your model.tar.gz on s3
   role=role,                      # iam role with permissions to create an Endpoint
   transformers_version="4.34.1",  # transformers version used
   pytorch_version="1.13.1",       # pytorch version used
   py_version='py310',             # python version used
   model_server_workers=1,         # number of workers for the model server
)
 
# deploy the endpoint endpoint
predictor = huggingface_model.deploy(
    initial_instance_count=1,      # number of instances
    instance_type="ml.inf2.8xlarge", # AWS Inferentia Instance
    volume_size = 100
)
# ignore the "Your model is not compiled. Please compile your model before using Inferentia." warning, we already compiled our model.
# We need to sent a warmup request to the endpoint, which loads the model on the neuron device
# this takes around 2 minutes
print("send warmup request")
try:
    predictor.predict({"inputs": [{"role":"user","content":"warmup"}]})
except:
    time.sleep(90)

5. Run inference and chat with Llama 2

The .deploy() returns an HuggingFacePredictor object which can be used to request inference. Our endpoint expects a json with messages. Since we are leveraging the new apply_chat_template in our inference.py script we can send "openai" like converstaions to our model.

Additionally we can send inference parameters, e.g. top_p or temperature using the parameters key.

# OpenAI like conversational messages
messages = [
  {"role": "system", "content": "You are an helpful AWS Expert Assistant. Respond only with 1-2 sentences."},
  {"role": "user", "content": "What is Amazon SageMaker?"},
]
 
# generation parameters
parameters = {
    "do_sample" : True,
    "top_p": 0.6,
    "temperature": 0.9,
    "top_k": 50,
    "max_new_tokens": 512,
    "repetition_penalty": 1.03,
}
 
# run prediction
response = predictor.predict({
  "inputs": messages,
  "parameters": parameters
  }
)
 
# lets our response to the messages and print the generation
messages.append({"role": "assistant", "content": response["generation"]})
 
# small helper function to print the messages
def pretty_print(messages):
    for message in messages:
        print(f"{message['role']}: {message['content']}")
 
pretty_print(messages)

Since Llama is a conversational model lets ask a follow up question. Therefore we can extend our messages with a new message.

# add follow up question
messages.append({"role": "user", "content": "Can I run Hugging Face Transformers on it?"})
 
# run prediction
response = predictor.predict({
  "inputs": messages,
  "parameters": parameters
  }
)
 
# lets our response to the messages and print the generation
messages.append({"role": "assistant", "content": response["generation"]})
pretty_print(messages)

Result:

system: You are an helpful AWS Expert Assistant. Respond only with 1-2 sentences.
user: What is Amazon SageMaker?
assistant: Amazon SageMaker is a fully managed service that provides a range of machine learning (ML) algorithms, tools, and frameworks to build, train, and deploy ML models at scale. It allows data scientists and engineers to focus on building better ML models instead of managing infrastructure.
user: Can I run Hugging Face Transformers on it?
assistant: Yes, you can run Hugging Face Transformers on Amazon SageMaker. Amazon SageMaker provides a pre-built Python SDK that supports popular deep learning frameworks like Hugging Face Transformers, making it easy to use these frameworks in your machine learning workflows.

If you are interested in the performance of Inferentia2 for throughput and latency check out Make your llama generation time fly with AWS Inferentia2 blog post.

Delete model and endpoint

To clean up, we can delete the model and endpoint.

predictor.delete_model()
predictor.delete_endpoint()

Conclusion

In this end-to-end tutorial, we walked through deploying Llama 2, a large conversational AI model, for low-latency inference using AWS Inferentia2 and Amazon SageMaker.

We converted the model with optimum-neuron, created a custom inference script, deployed a real-time endpoint, and chatted with Llama 2 using Inferentia2 acceleration.