Glen Knight

Amazon ECS Now Supports EC2 Inf1 Instances

August 14, 2020 by knightglen_sruobz

As machine learning and deep learning models become more sophisticated, hardware acceleration is increasingly required to deliver fast predictions at high throughput. Today, we’re very happy to announce that AWS customers can now use the Amazon EC2 Inf1 instances on Amazon ECS, for high performance and the lowest prediction cost in the cloud. For a few weeks now, these instances have also been available on Amazon Elastic Kubernetes Service.

A primer on EC2 Inf1 instances
Inf1 instances were launched at AWS re:Invent 2019. They are powered by AWS Inferentia, a custom chip built from the ground up by AWS to accelerate machine learning inference workloads.

Inf1 instances are available in multiple sizes, with 1, 4, or 16 AWS Inferentia chips, with up to 100 Gbps network bandwidth and up to 19 Gbps EBS bandwidth. An AWS Inferentia chip contains four NeuronCores. Each one implements a high-performance systolic array matrix multiply engine, which massively speeds up typical deep learning operations such as convolution and transformers. NeuronCores are also equipped with a large on-chip cache, which helps cut down on external memory accesses, saving I/O time in the process. When several AWS Inferentia chips are available on an Inf1 instance, you can partition a model across them and store it entirely in cache memory. Alternatively, to serve multi-model predictions from a single Inf1 instance, you can partition the NeuronCores of an AWS Inferentia chip across several models.

Compiling Models for EC2 Inf1 Instances
To run machine learning models on Inf1 instances, you need to compile them to a hardware-optimized representation using the AWS Neuron SDK. All tools are readily available on the AWS Deep Learning AMI, and you can also install them on your own instances. You’ll find instructions in the Deep Learning AMI documentation, as well as tutorials for TensorFlow, PyTorch, and Apache MXNet in the AWS Neuron SDK repository.

In the demo below, I will show you how to deploy a Neuron-optimized model on an ECS cluster of Inf1 instances, and how to serve predictions with TensorFlow Serving. The model in question is BERT, a state of the art model for natural language processing tasks. This is a huge model with hundreds of millions of parameters, making it a great candidate for hardware acceleration.

Creating an Amazon ECS Cluster
Creating a cluster is the simplest thing: all it takes is a call to the CreateCluster API.

$ aws ecs create-cluster --cluster-name ecs-inf1-demo

Immediately, I see the new cluster in the console.

Several prerequisites are required before we can add instances to this cluster:

• An AWS Identity and Access Management (IAM) role for ECS instances: if you don’t have one already, you can find instructions in the documentation. Here, my role is named ecsInstanceRole.
• An Amazon Machine Image (AMI) containing the ECS agent and supporting Inf1 instances. You could build your own, or use the ECS-optimized AMI for Inferentia. In the us-east-1 region, its id is ami-04450f16e0cd20356.
• A Security Group, opening network ports for TensorFlow Serving (8500 for gRPC, 8501 for HTTP). The identifier for mine is sg-0994f5c7ebbb48270.
• If you’d like to have ssh access, your Security Group should also open port 22, and you should pass the name of an SSH key pair. Mine is called admin.

We also need to create a small user data file in order to let instances join our cluster. This is achieved by storing the name of the cluster in an environment variable, itself written to the configuration file of the ECS agent.

#!/bin/bash
echo ECS_CLUSTER=ecs-inf1-demo >> /etc/ecs/ecs.config

We’re all set. Let’s add a couple of Inf1 instances with the RunInstances API. To minimize cost, we’ll request Spot Instances.

$ aws ec2 run-instances
--image-id ami-04450f16e0cd20356
--count 2
--instance-type inf1.xlarge
--instance-market-options '{"MarketType":"spot"}'
--tag-specifications 'ResourceType=instance,Tags=[{Key=Name,Value=ecs-inf1-demo}]'
--key-name admin
--security-group-ids sg-0994f5c7ebbb48270
--iam-instance-profile Name=ecsInstanceRole
--user-data file://user-data.txt

Both instances appear right away in the EC2 console.

A couple of minutes later, they’re ready to run tasks on the cluster.

Our infrastructure is ready. Now, let’s build a container storing our BERT model.

Building a Container for Inf1 Instances
The Dockerfile is pretty straightforward:

• Starting from an Amazon Linux 2 image, we open ports 8500 and 8501 for TensorFlow Serving.
• Then, we add the Neuron SDK repository to the list of repositories, and we install a version of TensorFlow Serving that supports AWS Inferentia.
• Finally, we copy our BERT model inside the container, and we load it at startup.

Here is the complete file.

FROM amazonlinux:2
EXPOSE 8500 8501
RUN echo $'[neuron] n
name=Neuron YUM Repository n
baseurl=https://yum.repos.neuron.amazonaws.com n
enabled=1' > /etc/yum.repos.d/neuron.repo
RUN rpm --import https://yum.repos.neuron.amazonaws.com/GPG-PUB-KEY-AMAZON-AWS-NEURON.PUB
RUN yum install -y tensorflow-model-server-neuron
COPY bert /bert
CMD ["/bin/sh", "-c", "/usr/local/bin/tensorflow_model_server_neuron --port=8500 --rest_api_port=8501 --model_name=bert --model_base_path=/bert/"]

Then, I build and push the container to a repository hosted in Amazon Elastic Container Registry. Business as usual.

$ docker build -t neuron-tensorflow-inference .

$ aws ecr create-repository --repository-name ecs-inf1-demo

$ aws ecr get-login-password | docker login --username AWS --password-stdin 123456789012.dkr.ecr.us-east-1.amazonaws.com

$ docker tag neuron-tensorflow-inference 123456789012.dkr.ecr.us-east-1.amazonaws.com/ecs-inf1-demo:latest

$ docker push

Now, we need to create a task definition in order to run this container on our cluster.

Creating a Task Definition for Inf1 Instances
If you don’t have one already, you should first create an execution role, i.e. a role allowing the ECS agent to perform API calls on your behalf. You can find more information in the documentation. Mine is called ecsTaskExecutionRole.

The full task definition is visible below. As you can see, it holds two containers:

• The BERT container that I built,
• A sidecar container called neuron-rtd, that allows the BERT container to access NeuronCores present on the Inf1 instance. The AWS_NEURON_VISIBLE_DEVICES environment variable lets you control which ones may be used by the container. You could use it to pin a container on one or several specific NeuronCores.

{
  "family": "ecs-neuron",
  "executionRoleArn": "arn:aws:iam::123456789012:role/ecsTaskExecutionRole",
  "containerDefinitions": [
    {
      "entryPoint": [
        "sh",
        "-c"
      ],
      "portMappings": [
        {
          "hostPort": 8500,
          "protocol": "tcp",
          "containerPort": 8500
        },
        {
          "hostPort": 8501,
          "protocol": "tcp",
          "containerPort": 8501
        },
        {
          "hostPort": 0,
          "protocol": "tcp",
          "containerPort": 80
        }
      ],
      "command": [
        "tensorflow_model_server_neuron --port=8500 --rest_api_port=8501 --model_name=bert --model_base_path=/bert"
      ],
      "cpu": 0,
      "environment": [
        {
          "name": "NEURON_RTD_ADDRESS",
          "value": "unix:/sock/neuron-rtd.sock"
        }
      ],
      "mountPoints": [
        {
          "containerPath": "/sock",
          "sourceVolume": "sock"
        }
      ],
      "memoryReservation": 1000,
      "image": "123456789012.dkr.ecr.us-east-1.amazonaws.com/ecs-inf1-demo:latest",
      "essential": true,
      "name": "bert"
    },
    {
      "entryPoint": [
        "sh",
        "-c"
      ],
      "portMappings": [],
      "command": [
        "neuron-rtd -g unix:/sock/neuron-rtd.sock"
      ],
      "cpu": 0,
      "environment": [
        {
          "name": "AWS_NEURON_VISIBLE_DEVICES",
          "value": "ALL"
        }
      ],
      "mountPoints": [
        {
          "containerPath": "/sock",
          "sourceVolume": "sock"
        }
      ],
      "memoryReservation": 1000,
      "image": "790709498068.dkr.ecr.us-east-1.amazonaws.com/neuron-rtd:latest",
      "essential": true,
      "linuxParameters": { "capabilities": { "add": ["SYS_ADMIN", "IPC_LOCK"] } },
      "name": "neuron-rtd"
    }
  ],
  "volumes": [
    {
      "name": "sock",
      "host": {
        "sourcePath": "/tmp/sock"
      }
    }
  ]
}

Finally, I call the RegisterTaskDefinition API to let the ECS backend know about it.

$ aws ecs register-task-definition --cli-input-json file://inf1-task-definition.json

We’re now ready to run our container, and predict with it.

Running a Container on Inf1 Instances
As this is a prediction service, I want to make sure that it’s always available on the cluster. Instead of simply running a task, I create an ECS Service that will make sure the required number of container copies is running, relaunching them should any failure happen.

$ aws ecs create-service --cluster ecs-inf1-demo
--service-name bert-inf1
--task-definition ecs-neuron:1
--desired-count 1

A minute later, I see that both task containers are running on the cluster.

Predicting with BERT on ECS and Inf1
The inner workings of BERT are beyond the scope of this post. This particular model expects a sequence of 128 tokens, encoding the words of two sentences we’d like to compare for semantic equivalence.

Here, I’m only interested in measuring prediction latency, so dummy data is fine. I build 100 prediction requests storing a sequence of 128 zeros. Using the IP address of the BERT container, I send them to the TensorFlow Serving endpoint via grpc, and I compute the average prediction time.

Here is the full code.

import numpy as np
import grpc
import tensorflow as tf
from tensorflow_serving.apis import predict_pb2
from tensorflow_serving.apis import prediction_service_pb2_grpc
import time

if __name__ == '__main__':
    channel = grpc.insecure_channel('18.234.61.31:8500')
    stub = prediction_service_pb2_grpc.PredictionServiceStub(channel)
    request = predict_pb2.PredictRequest()
    request.model_spec.name = 'bert'
    i = np.zeros([1, 128], dtype=np.int32)
    request.inputs['input_ids'].CopyFrom(tf.contrib.util.make_tensor_proto(i, shape=i.shape))
    request.inputs['input_mask'].CopyFrom(tf.contrib.util.make_tensor_proto(i, shape=i.shape))
    request.inputs['segment_ids'].CopyFrom(tf.contrib.util.make_tensor_proto(i, shape=i.shape))

    latencies = []
    for i in range(100):
        start = time.time()
        result = stub.Predict(request)
        latencies.append(time.time() - start)
        print("Inference successful: {}".format(i))
    print ("Ran {} inferences successfully. Latency average = {}".format(len(latencies), np.average(latencies)))

For convenience, I’m running this code on an EC2 instance based on the Deep Learning AMI. It comes pre-installed with a Conda environment for TensorFlow and TensorFlow Serving, saving me from installing any dependencies.

$ source activate tensorflow_p36
$ python predict.py

On average, prediction took 56.5ms. As far as BERT goes, this is pretty good!

Ran 100 inferences successfully. Latency average = 0.05647835493087769

Getting Started
You can now deploy Amazon Elastic Compute Cloud (EC2) Inf1 instances on Amazon ECS today in the US East (N. Virginia) and US West (Oregon) regions. As Inf1 deployment progresses, you’ll be able to use them with Amazon ECS in more regions.

Give this a try, and please send us feedback either through your usual AWS Support contacts, on the AWS Forum for Amazon ECS, or on the container roadmap on Github.

– Julien

Source: AWS News