Blog – #nix

Running Emacs in systemd's session.slice

I use Emacs and EXWM as my window manager. For this setup, running an Emacs daemon as a systemd-user unit allows me to attach multiple clients to this process (for instance, to work in the same session through an SSH connection on my iPad), and have the daemon survive restarts of my graphical session. However, all subprocesses started from within Emacs—which are virtually all applications & shells on my system—are then tracked within the same systemd scope. This means that a single application consuming excessive amounts of memory can bring down my entire user session (looking at you, Firefox). This post documents how you can move this Emacs daemon from the systemd app.slice into the more appropriate session.slice, and run applications & shells from within Emacs in their own scopes in app.slice.