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tfjs-backend-wasm

README.md

Usage

This package adds a WebAssembly backend to TensorFlow.js. This is currently in alpha and subject to change. Not every op in TensorFlow.js is supported on this backend.

Importing this package augments the TensorFlow.js package (@tensorflow/tfjs-core) by registering a new backend meaning existing TensorFlow.js code, models, and dependent packages will work with only a few lines of code changed.

Importing the backend

Via NPM

// Import @tensorflow/tfjs or @tensorflow/tfjs-core
import * as tf from '@tensorflow/tfjs';

// Import the WASM backend.
import '@tensorflow/tfjs-backend-wasm';

Via a script tag

<!-- Import @tensorflow/tfjs or @tensorflow/tfjs-core -->
<script src="https://cdn.jsdelivr.net/npm/@tensorflow/tfjs"></script>

<!-- Import the WASM backend. -->
<script src="https://cdn.jsdelivr.net/npm/@tensorflow/tfjs-backend-wasm"></script>

Using the backend with MobileNet

async function main() {
  // Set the backend to WASM and wait for the module to be ready.
  await tf.setBackend('wasm');

  let img = tf.browser.fromPixels(document.getElementById('img'))
      .resizeBilinear([224, 224])
      .expandDims(0)
      .toFloat();

  let model = await tf.loadGraphModel(
    'https://tfhub.dev/google/imagenet/mobilenet_v2_100_224/classification/2',
    {fromTFHub: true});
  const y = model.predict(img);

  y.print();
}
main();

Our WASM backend builds on top of the XNNPACK library which provides high-efficiency floating-point neural network inference operators.

FAQ

How many ops have you implemented?

See all_kernels.ts for an up-to-date list of supported ops. We love contributions. See the contributing document for more info.

Do you support training?

Maybe. There are still a decent number of ops that we are missing in WASM that are needed for gradient computation. At this point we are focused on making inference as fast as possible.

Do you work in node?

Yes. If you run into issues, please let us know.

Do you support SIMD?

We are actively working on adding SIMD before we do the official release. The switch to SIMD should happen transparently for browsers that support it.

Do you support multi-threading?

Multi-threading support is not a priority for us at this point since it is still a proposal. We will keep a close eye on it as the proposal progresses.

Development

Emscripten installation

Install the Emscripten SDK (version 1.39.1):

git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
./emsdk install 1.39.1
./emsdk activate 1.39.1

Prepare the environment

Before developing, make sure the environment variable EMSDK points to the emscripten directory (e.g. ~/emsdk). Emscripten provides a script that does the setup for you:

Cd into the emsdk directory and run:

source ./emsdk_env.sh

For details, see instructions here.

Building

yarn build

Testing

yarn test

Deployment

./scripts/build-npm.sh
npm publish