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GVFS for Mac

3 posts · Feb 2017 – Mar 2018

What this trail covers

This thread tracks the evolution of GVFS (Git Virtual File System) to support platforms beyond Windows. Initially developed for Windows to enable efficient work in extremely large Git repositories, this thread now includes the design and prototyping of GVFS for macOS. The macOS implementation leverages Kauth kernel extensions to virtualize file system operations, allowing for on-demand enumeration and content loading. Early prototype results show promising application compatibility, especially for large repositories. This post introduces the initial GVFS client code for Windows, its protocol extension, and modifications to Git to support GVFS-backed repositories, aiming to enable Git to scale to repos of any size by virtualizing the file system and only downloading files on demand.

All Microsoft trails
  1. GVFS for MacThis post details the design approach for GVFS on macOS, which differs from the Windows implementation due to macOS's lack of stacked filter drivers. It introduces the use of Kauth kernel extensions to intercept file system operations like directory enumeration and file reads. The post outlines the concept of placeholder files and directories, and how the kernel extension (GvKext) communicates with a user-mode process (GVFS) to dynamically populate file system content. It also presents initial prototype results validating application compatibility and performance for builds on virtual projections of large codebases.
  2. GVFS Updates: More Performance, More AvailabilityThis post details performance improvements in GVFS, including an O(modified) approach that scales with edited files rather than downloaded files. It also describes optimizations to `git status` by updating Git configuration with more granularity to avoid slowdowns, and the removal of a network roundtrip during `git add` and `git commit` by disabling server-side object existence checks. A custom database engine tuned for GVFS needs has replaced the Extensible Storage Engine (ESE). Additionally, GVFS 1.0 is now available with pre-built binaries, simplifying installation for users on Windows 10 Creators Update or later. The post also announces industry adoption of GVFS by GitHub and experimental support by Bitbucket, with SourceTree, Tower for Windows, and gmaster clients also supporting GVFS.
  3. Announcing GVFS (Git Virtual File System)Introduces GVFS (Git Virtual File System) as a solution for scaling Git to extremely large repositories (e.g., Windows codebase with 3.5M+ files, 270GB+). GVFS virtualizes the file system, downloading files only when opened. It manages how much of the repo Git considers for operations like checkout and status. This results in significantly faster operations: clone in minutes (vs. 12+ hours), checkout in seconds (vs. hours), and status in seconds (vs. minutes). The trade-off is a slightly longer first build due to on-demand file downloads. The client code is open-sourced on GitHub, along with modifications to Git to work with GVFS-backed repos and the GVFS protocol extension.