Operating Systems - David Vernon

Processes
Process Scheduling
– Two Level Scheduling
» What if not all runnable processes are in memory
(some might have been swapped out to disk)?
» The context switch time for a swapped process is
orders of magnitude longer than that of a process
in memory
» Solution: use two schedulers:
high-level scheduler decides which processes should be
memory-resident and which should be swapped to disk
(i.e. it schedules memory)
low-level scheduler runs/suspends memory resident
processes Copyright © (i.e. 2007 David it schedules Vernon (www.vernon.eu) CPU time)