---
title: MPS training (basic)
description: 'Audience: Users looking to train on their Apple silicon GPUs.'
canonical: 'https://lightning.ai/docs/pytorch/stable/reference/accelerators/mps_basic'
---
# MPS training (basic) {#mps-training-basic}

**Audience:** Users looking to train on their Apple silicon GPUs.

> **Warning**
>
> Both the MPS accelerator and the PyTorch backend are still experimental.
> As such, not all operations are currently supported. However, with ongoing development from the PyTorch team, an increasingly large number of operations are becoming available.
> You can use `PYTORCH_ENABLE_MPS_FALLBACK=1 python your_script.py` to fall back to cpu for unsupported operations.

## What is Apple silicon? {#what-is-apple-silicon}

Apple silicon chips are a unified system on a chip (SoC) developed by Apple based on the ARM design.
Among other things, they feature CPU-cores, GPU-cores, a neural engine and shared memory between all of these features.

## So it's a CPU? {#so-it-s-a-cpu}

Apple silicon includes CPU-cores among several other features. However, the full potential for the hardware acceleration of which the M-Socs are capable is unavailable when running on the `CPUAccelerator`. This is because they also feature a GPU and a neural engine.

To use them, Lightning supports the `MPSAccelerator`.

## Run on Apple silicon gpus {#run-on-apple-silicon-gpus}

Enable the following Trainer arguments to run on Apple silicon gpus (MPS devices).

```python
trainer = Trainer(accelerator="mps", devices=1)
```

> **Note**
>
> The `MPSAccelerator` only supports 1 device at a time. Currently there are no machines with multiple MPS-capable GPUs.

## What does MPS stand for? {#what-does-mps-stand-for}

MPS is short for [Metal Performance Shaders](https://developer.apple.com/metal/)  which is the technology used in the back for gpu communication and computing.

## Troubleshooting {#troubleshooting}

If Lightning can't detect the Apple Silicon hardware, it will raise this exception:

```yaml
MisconfigurationException: `MPSAccelerator` can not run on your system since the accelerator is not available.
```

If you are seeing this despite running on an ARM-enabled Mac, the most likely cause is that your Python is being emulated and thinks it is running on an Intel CPU.
To solve this, re-install your python executable (and if using environment managers like conda, you have to reinstall these as well) by downloading the Apple M1/M2 build (not Intel!), for example [here](https://docs.conda.io/en/latest/miniconda.html#latest-miniconda-installer-links).

---

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- Parent: [Accelerators](/docs/pytorch/2.6.6/reference/accelerators.md)