So before Borgmon existed, the quota unit was basically an entire machine? No virtualization?
Oh wait, this was probably 2008, VMWare had only just figured out JITed software virtualization a couple years prior. Makes a bit more sense now. And now the containerization thing makes a tad more sense: Google basically skipped over the "use QEMU" (or more recently, Firecracker) phase everyone else is now going through.
Borg was started in 2003 and by 2006-2007 was already the default way to run things, even though isolation wasn't perfect then. I think it started with chroot jails, then fake NUMA, then cgroups, which were written for it. It took years before all of web search moved to dedicated Borg machines (their quota belonged to you and nobody else could run on them) and, eventually, shared ones.
Oh wait, this was probably 2008, VMWare had only just figured out JITed software virtualization a couple years prior. Makes a bit more sense now. And now the containerization thing makes a tad more sense: Google basically skipped over the "use QEMU" (or more recently, Firecracker) phase everyone else is now going through.