Create an engine to run a model

To run a model, you need to create a worker. A worker is the engine that breaks the model down into executable tasks and schedules the tasks to run on a backend, usually the GPU or CPU.

Create a Worker

Use new Worker(...) to create a worker. You must specify a backend type, which tells Sentis where to run the worker and a runtime model.

For example, the following code creates a worker that runs on the GPU using Sentis compute shaders.

using UnityEngine;
using Unity.Sentis;

public class CreateWorker : MonoBehaviour
{
    ModelAsset modelAsset;
    Model runtimeModel;
    Worker worker;

    void Start()
    {
        runtimeModel = ModelLoader.Load(modelAsset);
        worker = new Worker(runtimeModel, BackendType.GPUCompute);
    }
}

Backend types

Sentis provides CPU and GPU backend types. To understand how Sentis executes operations using the different backends, refer to How Sentis runs a model.

If a backend type doesn't support a Sentis layer in a model, the worker will assert. Refer to Supported ONNX operators for more information.

Among the backend types, BackendType.GPUCompute and BackendType.CPU are the fastest. Only use BackendType.GPUPixel if the platform does not support compute shaders. To check if your runtime platform supports compute shaders, use SystemInfo.supportsComputeShaders.

If you use BackendType.CPU with WebGL, Burst compiles to WebAssembly code which might be slow. Refer to Getting started with WebGL development for more information.

The speed of model execution depends on the platform's support for multithreading in Burst or its full support for compute shaders. You can profile a model to understand the performance of a model.

Additional resources