====== Multiprocessing ======

multiple cores

Process/Thread per CPU
  $ ps -e | grep migration
  $ ps -e | grep ksoftirq
  $ ps -e | grep cpuhp
  $ ps -e | grep idle_inject
  $ ps -e | grep kworker (multiple per cpu)

kernel stack running at ring 0

each process has two stacks
user space stack
kernel space stack

separation: if the user stack is corrupted, we don’t want the kernel clobbered