udevsettle is a hack that waits for the kevent queue to finish. I believe the justification for it was that certain volume and storage technologies on Linux act

udevsettle is a hack that waits for the kevent queue to finish. I believe the justification for it was that certain volume and storage technologies on Linux act in a synchronous probing fashion that expect all devices to be up simultaneously before initializing. It's frequently mentioned as a bottleneck, including here: https://wiki.freedesktop.org/www/Software/systemd/Optimizations/ https://wiki.freedesktop.org/www/Software/systemd/Optimizati... As for NetworkManager's wait online service, see what timeout has been set inside the unit file, and try lowering it. Though I suspect this might be yet another hack implemented as a synchronization point for network-dependent services to initialize properly, given just how finicky it is to define what a "network is up" state actually entails.