dircacher

A simple utility to improve system performance by caching inodes, meant to be run on startup.

The basic idea behind dircacher is that a program will first have to check if a file exists before it can be opened (whether this is handled by the kernel in a TOCTOU safe manner is irrelevant). And that there exist programs that will not actually open any files but instead read their metadata.

All that dircacher does is read every inode on given subfolders, without traversing symlinks or separate filesystems, in a multithreaded fashion. On a linux system with enough spare RAM, this will store the filesystem tree including metadata in the "fscache", leading to decreased latency when a user is interacting with any part of the filesystem.

In my experience, this has made my computer noticeably snappier after a reboot and takes very little time to do its work; 3 HDD RAID5 array with 1M inodes + 256GB SATA SSD with 2M inodes cached completely in ~~1m45sec~~ 1m22sec (as of 0.4.0).
Others are welcome to share their own startup times and experience with dircacher, perhaps a table could be made

Installation

Arch based systems

Option 1: Prepackaged

Go to the latest release for a prepackaged tarball

Option 2: DIY

Run arch-prepare.sh to load source files into the arch-pkg directory
cd into the arch-pkg directory
makepkg to build the pacman package
pacman -U to install to your system

An example:

./arch-prepare.sh
cd arch-pkg
makepkg
sudo pacman -U dircacher-bin{VERSION_HERE}.tar.zst

Other distributions

Repeat arch installation steps and convert the generated arch package to a deb/rpm using a tool. I might add rpm/deb packages at another point

Configuration

A file called /etc/systemd/system/dircacher.service should have been created, modify the ExecStart to pass in any mountpoints you wish to cache on startup, and then enable dircacher.service on startup.

For example on a btrfs system that splits home and root into two subvolumes:

ExecStart=dircacher / /home