https://www.scrivano.org/tags/memory/ Recent content in Memory on *scratch* Hugo en Tue, 11 Aug 2026 14:08:58 +0200 https://www.scrivano.org/posts/2026-08-11-sharing-erofs-superblocks-across-container-mounts/ Tue, 11 Aug 2026 10:00:00 +0200 https://www.scrivano.org/posts/2026-08-11-sharing-erofs-superblocks-across-container-mounts/ <p>For a while now we&rsquo;ve had composefs support in the container-libs. For each OCI layer in an image, we build a read-only EROFS blob that can be verified with fs-verity and that the kernel mounts directly. It works well if you look at a single container, but the moment you start thinking about composefs as the storage for a real container host where many containers are running, we have a problem. Many of them share the same image layers but with composefs every one of those containers mounts the same EROFS blobs, and each mount is a separate world as far as the kernel is concerned. The bytes on disk are shared, but the memory used to cache them is not. That is one of the reasons composefs is not yet the default way to store and run containers, and it is what I want to talk about here.</p>