How running a background task takes a tiny fraction of second, although the task itself takes seconds or minutes, and why it’s run on E cores.
CTS
How macOS schedules tasks like making automatic Time Machine backups, from property list to transactions between DAS and CTS.
The story of how Mac OS X went from cron, to launchd, and ended up with Duet Activity Scheduler, to schedule background activities like backups.
Although there doesn’t appear to be any straightforward way to run command tools or scripts only on Efficiency cores, there are ways and means.
Prior to 10.4, Mac OS X used cron, then scheduling became part of the job of launchd. Later Apple added a new subsystem, Duet Activity Scheduler, which continues to evolve.
How the start of Time Machine backups to APFS volumes is scheduled and dispatched, and a fascinating Secure Backup Daemon.
How Time Machine has changed since it appeared in 2007, and how backing up to APFS volumes is different now it’s available in Big Sur.
CTS now schedules many important services, including syncing Calendar, Contacts, Messages, running weekly firmware checks with eficheck, and more.
CTS scheduling and dispatch of background tasks has no user interface, and no controls. How can you tell that there’s a problem, and what to do about it?
What does it take for an app to have ‘activities’ managed for efficiency by CTS? Not a lot – but in return, the management is a black box.
The Eclectic Light Company 