# Swap Space

Runners come without swap by default; when a job runs out of memory, one or more processes get terminated by the out-of-memory killer. Adding a swap file lets the kernel page cold memory out to disk, which can carry a job past short memory spikes without moving to a larger shape.

See the [Runner Controls overview](/content/docs/solutions/github-actions/runner-controls.md) for how to pass these settings via a profile or labels.

**With runner profiles**

You can configure swap directly in the [profile editor](https://cloud.namespace.so/workspace/actions/profiles) under `Advanced Settings`.

**With runner labels**

For label-based runners, automatic swap configuration is not yet supported. Swap can still be enabled manually using `container.privileged` and `container.mount-scratch`. The scratch mount is required because Linux does not support activating a swap file on the runner's default overlay-backed filesystem.

`/namespace/scratch` provides an ephemeral filesystem that can be used for swap.

When using runner labels, request the features with `namespace-features` and create the swap file in `/namespace/scratch`.

```yaml
theme={null}
jobs:
  build:
    runs-on:
      - nscloud-ubuntu-22.04-amd64-4x8-with-features
      - namespace-features:container.privileged=true;container.mount-scratch=true

steps:
      - name: Set up swap
        run: |
          sudo fallocate -l 16G /namespace/scratch/swapfile
          sudo chmod 600 /namespace/scratch/swapfile
          sudo mkswap /namespace/scratch/swapfile
          sudo swapon /namespace/scratch/swapfile
```

## Next steps

* [Runner Controls overview](/content/docs/solutions/github-actions/runner-controls.md)
* [Privileged workflows](/content/docs/solutions/github-actions/runner-controls/privileged-workflows.md)