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OpenVINO™ optimize Fairseq S2T model

December 14, 2022

OpenVINO™ Optimize Fairseq S2T Model


Fairseq is a sequence modeling toolkit that allows researchers and developers to train custom models for translation, summarization, language modeling and other text generation tasks.

There are 2 steps to generate model ready for OpenVINO™ acceleration:

1. Use torch.export.onnx function convert the “.pt” model to “.onnx” model;

2. Use OpenVINO™ MO toolkit convert the “.onnx” model to “IR” model.

Figure 1. OpenVINO™ optimize Fairseq model workflow

The following graph is the Fairseq framework inference workflow, it defines the model structure by “Model Config”, composes “Model Definition List” through multiple subgraph models, and dynamically loads the submodules in the model inference runtime.

Such as in the S2T task, model consists of two parts: Encoder and Decoder.
·       Encoder is for extracting feature information from audio file.
·       Decoder is for decoding the feature information to generate text information.

Fairseq Inference workflow

The length of audio information will affect the length of the feature information, and the length of the feature information will affect the Decoder submodule loop’s times. Therefore, the structure of the S2T model is dynamically defined according to the length of the input audio.

Figure 2. Fairseq S2T model inference workflow

To optimize Fairseq framework model there’re 4 challenges need to be solved:
-       Fairseq define submodules for various function, include variable in model layer define.
-       Model structure is dynamically loaded in runtime and can’t export a whole torch model graph.
-       Encoder and Decoder part models’ input shapes are dynamic, depending on input data size.
-       Decoder part loop times depends by input sequence lengths.

OpenVINO™ optimize Fairseq workflow

So that we should use some optimization tricks to solve these problems, to make sure the pipeline optimized by OpenVINO™.
-       Divide model into Encoder and Decoder two parts, and separately export to onnx model,
-       Because of the model structure define by input seq_len, should export dynamic shape onnx model.
-       Convert onnx to IR model by OpenVINO™ MO toolkit.
-       Replace the Fairseq S2T task pipeline Encoder and Decoder into IR model.
-       Loading Inference Engine to run pipeline the pipeline on OpenVINO™.

Figure 3. OpenVINO™ optimize Fairseq S2T model workflow


-       Fairseq is a sequence modeling toolkit that allows researchers and developers to train custom models for translation, summarization, language modeling and other text generation tasks
-       OpenVINO™ is an open-source toolkit for optimizing and deploying AI inference which can boost deep learning performance in computer vision, automatic speech recognition, natural language processing and other common task.
-       Python version >=3.8
-       PyTorch version >=1.10.0
Reference: GitHub: Fairseq-OpenVINO

Quick Start Demo

Step 1. Install fairseq and requirement

# Install Fairseq
git clone https://github.com/pytorch/fairseq
cd fairseq
pip install --editable ./
#(Optional) Install the latest stable release (0.10.x)
pip install fairseq

#Install OpenVINO™
Reference: Install OpenVINO by source code for Linux
Reference: Install OpenVINO by release package

Step 2. Download audio file and pre-train model file

In this blog we refer the “S2T Example: STon CoVoST” as sample, Preparation dataset and pre-train model can follow the Fairseq original step. Also, you can use “torch audio” to convert audio file to build customer dataset.

import torchaudio
# load tensor from file
waveform, sample_rate = torchaudio.load('foo.arm') 
# save tensor to file
torchaudio.save('foo_save.wav', waveform, sample_rate)

Step 3. Modify code to export onnx

Torch model export to onnx, We should adjust the contents in fairseq/sequence_generator.py +781 line "self.save_onnx = True" , +782 line "self.openvino_engine = False" The encoder.onnx and decoder.onnx will save in models

python fairseq_cli/interactive.py datasets/en/ --config-yaml config_st_en_de.yaml --task speech_to_text --path models/covost2_fr_en_st_transformer_s.pt --max-tokens 50000 --beam 1

Encoder part model export to dynamic onnx

Figure 4. Encoder part model export to dynamic onnx

Decoder part model export to dynamic onnx

Figure 5. Decoder part model export to dynamic onnx

Step 4. Convert Model to IR

Convert encoder.onnx and decoder.onnx to encoder.xml and decoder.xml

# Convert encoder onnx to IR
mo -m encoder.onnx --input "onnx::Transpose_0[-1,-1,-1],src_lengths[-1]"
# Convert decoder onnx to IR
mo -m decoder.onnx --input "prev_output_tokens[-1,-1],onnx::MatMul_1[-1,-1,-1]"

Step 5. OpenVINO™ Inference Engine optimize S2T pipeline

OpenVINO™ Inference S2T pipeline We should adjust the contents in fairseq/sequence_generator.py +781 line "self.save_onnx = False" , +782 line "self.openvino_engine =True" Use the converted the model to run OpenVINO™ Inference S2T pipeline.

python fairseq_cli/interactive.py datasets/en/ --config-yaml config_st_en_de.yaml --task speech_to_text --path models/covost2_fr_en_st_transformer_s.pt --max-tokens 50000 --beam 1

OpenVINO™ Inference Engine initialization

Figure 6. OpenVINO™ Inference Engine Initialization

Encoder part inference by OpenVINO™

Figure 7. Encoder part inference by OpenVINO™
Figure 8. Encoder part inference by OpenVINO™

Decoder part inference by OpenVINO™

Figure 9. Decoder part inference by OpenVINO™
Figure 10. Decoder part inference by OpenVINO™

Inference Result

Figure 11. Inference Result

Build OpenVINO on CentOS 7 with Script

December 7, 2022

Authors: Xiake Sun, Su Yang

We provide a script to help users easily install and test OpenVINO™ on CentOS 7.6. This script is a practice and supplement to the Building OpenVINO™ on CentOS 7 Guide in the OpenVINO™ wiki. The installation of OpenVINO™ 2022.1.0 and 2022.2.0 has been verified under the following eight configurations of CentOS 7.6 (GCC:7.3.1, 8.3.1 and Python: 3.6,3.7, 3.8, 3.9). The script could also be used for the newer version of OpenVINO with some modifications in the future.

CentOS 7 is an open-source server operating system released by the CentOS project. It was officially released on July 7, 2014. CentOS 7 is an enterprise-level Linux distribution, which is redistributed from the free and open-source code of RedHat, and its stability is trustworthy. The CentOS community and RedHat have announced that CentOS 8 will end on December 31, 2021, and CentOS 7 will end on June 30, 2024. Therefore, CentOS 7 is still the mainstream operating system of most cloud platforms.

However, CentOS 7 default GCC 4.8.5 and CMake 2.8.12 does not meet the OpenVINO software requirement for building on a Linux system. Since OpenVINO™ release 2022.1, the binary and python wheel installation packages will not be provided on CentOS 7. To help users with the verification and integration of the OpenVINO™ new version, Here we provide the installation guide and script.

Script Usage

1.Download OpenVINO™  and Script:

git clone https://github.com/openvinotoolkit/openvino.git -b 2022.2.0 && cd openvino
wget https://github.com/yangsu2022/openvino/blob/centos7-install-script/scripts/centos7_install_guide.sh -P ./script
chmod +x ./script/centos7_install_guide.sh

2.Usage Example:

./scripts/centos_install_guide.sh -g 8 -p 7 -c ~ -m resnet-50-pytorch -b true

3.Script Execution Time:

The environment configuration and dependency library download time are dependent on the network environment and will not be downloaded repeatedly. Compile time depends on the hardware. Every time the script is run, the user needs clean up the previous compilation-related folders (install, build, temp) and recompile.


Usage: [-g <7 or 8>] [-p <6, 7, 8 or9>] [-c <Cmake Dir>] [-m <evaluation model>] [-b benchmark_app C++ <true or false>]


The script steps are similar to the Building OpenVINO™ on CentOS 7 Guide. Here are the contents with some comments. For details, please refer to the script and wiki guide.

0. Install system dependencies setup on CentOS 7.6 and install Anaconda

To test more Python version, we use Anaconda instead of Miniconda. Anaconda silent installation is recommended to avoid manually agreeing to the certificate and restarting bash (the script part is as shown below).

1. Download CMake

Download the pre-built CMake 3.18.4 and add environment variables: no need to change the existing CMake version of the system and no need to compile.

2. Install devtoolset and setup environment

Because CentOS7 was released too early, the default GCC version is 4.8.5, which does not support the compilation of OpenVINO™. Using devtoolset can install a higher version of GCC without changing the system GCC version.

The library Wheel is one of Python dependencies. Wheel 0.37.1 is recommended for OpenVINO 2022.1.0 and 2022.2.0. The higher version of Wheel is not suitable.

3. Build OV with CMake

Create a Python environment with conda and check the name of Python library and header folder.

# download prebuild TBB instead of using system's

4. Install Python Wheels

Install the two generated wheels.(runtime and development tool)

5.Model evaluation with benchmark_app and OpenVINO™ CLI usage

Install the specified version of dependencies, for ONNX 1.12 not support python3.6.

pip install protobuf==3.16.0 onnx==1.11.0

Quickly download and convert models from OpenVINO™ Toolkit - Open Model Zoo repository.

C++/Python benchmark_app: The C++ version requires additional compilation, with the Python version by default.

In the end, the script will show the OpenVINO™ usage example as below.

Congratulation! centos7-install-guide is finished.
Here is an OV usage example on centos7:
source /opt/rh/devtoolset-8/enable
export PATH="~/anaconda3/bin:$PATH"
conda activate py37
benchmark_app -m ~/ov_models/public/resnet-50-pytorch/FP32/resnet-50-pytorch.xml -d CPU


Use Metrics to Scale Model Serving Deployments in Kubernetes

December 6, 2022

In this blog you will learn how to set up horizontal autoscaling in Kubernetes using inference performance metrics exposed by OpenVINO™ Model Server. This will enable efficient scaling of model serving pods for inference on Intel® CPUs and GPUs.

Figure 1. Visualization of autoscaling OpenVINO Model Server using Prometheus metrics in Kubernetes

Why use custom metrics?

OpenVINO™ Model Server provides high performance AI inference on Intel CPUs and GPUs that can be scaled in Kubernetes. However, when it comes to automatic scaling in Kubernetes, the Horizontal Pod Autoscaler by default, relies on CPU utilization and memory usage metrics only. Although resource consumption indicates how busy the application is, it does not clearly say whether serving provides expected quality of service to the clients or not. Since OpenVINO Model Server exposes performance metrics, we can automatically scale based on service quality rather than resource utilization.

The first metric that comes to mind when thinking about service performance is the duration of request processing, otherwise known as latency. For example, mean or median over a specified period or latency percentiles. OpenVINO Model Server provides such metrics but setting autoscaling based on latency requires specific knowledge about each model and the environment where the inference is running in order to properly set thresholds that trigger scaling.

While autoscaling based on latency works and may be a good choice when you have model-specific knowledge, we will instead focus on a more generic metric using ovms_requests_streams_ratio. Let’s dive into what this means.

In the equation above:

  • currently_processed_requests - number of inference requests to a model being processed by the service at a given time.
  • execution_streams_number – number of execution streams. (When a model is loaded on the device, its computing units are divided into streams. Each stream independently handles inference requests, meaning that the number of streams defines how many inferences can be run on the device in parallel. Note that the more streams there are, the less powerful they are, so we get more throughput at a cost of higher minimal latency / inference time.)

In this equation, for any model exceeding a value of 1 indicates that requests are starting to queue up. Setting the autoscaler threshold for the ovms_requests_streams_ratio metric is somewhat of an arbitrary decision that should be made by a cluster administrator. Setting the threshold too low will result in underutilization of nodes and setting it too high will force the system to work with insufficient resources for extended periods of time. Now that we have chosen a metric for autoscaling, let’s start setting it up.

Deploy Model Server with Autoscaling Metrics

First, we need to create a deployment of OpenVINO Model Server in Kubernetes. To do this, follow instructions to install the OpenVINO Operator in your Kubernetes cluster. Then create a configuration where we can specify the model to be served and enable metrics:

apiVersion: v1 
kind: ConfigMap 
  name: ovms-config 
  namespace: default 
  ovms_config.json: | 
    "model_config_list": [ 
            "config": { 
                 "name": "resnet50-int8", 
                 "base_path": "gs://ovms-public-eu/resnet50-binary" 
                 "enable": true 

Create ConfigMap:

kubectl apply -f https://raw.githubusercontent.com/openvinotoolkit/operator/main/examples/hpa_custom_metrics/ovms_config.yaml

With the configuration in place, we can deploy OpenVINO Model Server instance:

apiVersion: intel.com/v1alpha1 
kind: ModelServer 
  name: demo 
  image_name: 'openvino/model_server:2022.2' 
    grpc_port: 8080 
    rest_port: 8081 
    single_model_mode: false 
    config_configmap_name: 'ovms-config' 
    config_path: '/config/ovms_config.json' 
    file_system_poll_wait_seconds: 0 
    log_level: INFO 
    replicas: 1

Create ModelServer resource:

kubectl apply -f https://raw.githubusercontent.com/openvinotoolkit/operator/main/examples/hpa_custom_metrics/ovms.yaml

Deploy and Configure Prometheus

Next, we need to read serving metrics and expose them to the Horizontal Pod Autoscaler. To do this we will deploy Prometheus to collect serving metrics and the Prometheus Adapter to expose them to the autoscaler.  

Deploy Prometheus Monitoring Tool

Let’s start with Prometheus. In the example below we deploy a simple Prometheus instance via the Prometheus Operator. To deploy the Prometheus Operator, run the following command:

kubectl create -f https://raw.githubusercontent.com/prometheus-operator/prometheus-operator/v0.59.2/bundle.yaml

Next, we need to configure role-based access control to give Prometheus permission to access the Kubernetes API:

kubectl apply -f https://raw.githubusercontent.com/openvinotoolkit/operator/main/examples/hpa_custom_metrics/prometheus_rbac.yaml

The last step is to create a Prometheus instance by deploying Prometheus resource:

kubectl apply -f https://raw.githubusercontent.com/openvinotoolkit/operator/main/examples/hpa_custom_metrics/prometheus.yaml 

If the deployment was successful, a Prometheus service should be running on port 9090. You can set up a port forward for this service, enabling access to the web interface via localhost on your machine:

kubectl port-forward svc/prometheus-operated 9090:9090

Now, when you open http://localhost:9090 in a browser you should see the Prometheus user interface. Next, we need to expose the Model Server to Prometheus by creating a ServiceMonitor resource:

kubectl apply -f https://raw.githubusercontent.com/openvinotoolkit/operator/main/examples/hpa_custom_metrics/service_monitor.yaml

Once it’s ready, you should see a demo-ovms target in the Prometheus UI:

Figure 2. Prometheus User Interface with demo-ovms target

Now that the metrics are available via Prometheus, we need to expose them to the Horizonal Pod Autoscaler. To do this, we deploy the Prometheus Adapter.

Deploy Prometheus Adapter

Prometheus Adapter can be quickly installed via helm or step-by-step via kubectl. For the sake of simplicity, we will use helm3. Before deploying the adapter, we will prepare a configuration that tells it how to expose the ovms_requests_streams_ratio metric:  

apiVersion: v1 
kind: ConfigMap 
  name: adapter-config 
  namespace: default 
  config.yaml: |+ 
    - seriesQuery: 'ovms_current_requests' 
            resource: namespace 
            resource: pod 
        matches: "ovms_current_requests" 
        as: "ovms_requests_streams_ratio" 
      metricsQuery: avg(avg_over_time(ovms_current_requests{<<.LabelMatchers>>}[1m]) 
 / avg_over_time(ovms_streams{<<.LabelMatchers>>}[1m])) by (<<.GroupBy>>)

Create a ConfigMap:

kubectl apply –f https://raw.githubusercontent.com/openvinotoolkit/operator/main/examples/hpa_custom_metrics/prometheus_adapter_config.yaml

Now that we have a configuration, we can install the adapter:

helm repo add prometheus-community https://prometheus-community.github.io/helm-charts

helm repo update 

helm install --set 'prometheus.url=http://prometheus-operated.default.svc' --set 'rules.existing=adapter-config' prometheus-adapter prometheus-community/prometheus-adapter

Keep checking until custom metrics are available from the API:

kubectl get --raw /apis/custom.metrics.k8s.io/v1beta1 | jq 
  "kind": "APIResourceList", 
  "apiVersion": "v1", 
  "groupVersion": "custom.metrics.k8s.io/v1beta1", 
  "resources": [ 
      "name": "namespaces/ovms_requests_streams_ratio", 
      "singularName": "", 
      "namespaced": false, 
      "kind": "MetricValueList", 
      "verbs": [ 
      "name": "pods/ovms_requests_streams_ratio", 
      "singularName": "", 
      "namespaced": true, 
      "kind": "MetricValueList", 
      "verbs": [ 

Once you see the output above, you can configure the Horizontal Pod Autoscaler to use these metrics.

Set up Horizontal Pod Autoscaler

As mentioned previously, we will set up autoscaling based on the ovms_requests_streams_ratio metric and target an average value of 1. This will try to keep all streams busy all the time while preventing requests from queueing up. We will set minimum and maximum number of replicas to 1 and 3, respectively, and the stabilization window for both upscaling and downscaling to 120 seconds:

kind: HorizontalPodAutoscaler 
apiVersion: autoscaling/v2 
  name: ovms-hpa 
    apiVersion: intel.com/v1alpha1 
    kind: ModelServer 
    name: demo 
  minReplicas: 1 
  maxReplicas: 3 
  - type: Pods 
        name: ovms_requests_streams_ratio 
        type: AverageValue 
        averageValue: 1 
      stabilizationWindowSeconds: 120 
      stabilizationWindowSeconds: 120

Create HorizontalPodAutoscaler:

kubectl apply -f https://raw.githubusercontent.com/openvinotoolkit/operator/main/examples/hpa_custom_metrics/ovms_hpa.yaml 

Once deployed, you can generate some load for your model and see the results. Below you can see how Horizontal Pod Autoscaler scales the number of replicas by checking its status:

kubectl describe hpa ovms-hpa
Autoscaler Status

This data can also be visualized with a Grafana dashboard:

Metrics Visualized on Grafana Dashboard

As you can see, with OpenVINO Model Server metrics, you can quickly set up inferencing system with monitoring and autoscaling for any model. Moreover, with custom metrics, you can set up autoscaling for inference on any Intel CPUs and GPUs.  

See also: