Allocation and scheduling the processor
- The operating system keeps lists of those programs
("processes") that are
ready to run and those that are waiting on some I-O operation.
- A running process is put on the waiting list if it needs to do an I-O operation.
It is interrupted and put back on the ready list if its allotted time-slice has expired.
- A process moves from the waiting list to the ready list when
the I-O operation it was waiting for is completed.
- Whenever a process is swapped out (its status is changed from currently running to either waiting or ready)
the next available ready process is swapped in. NOTE: swapping need not necessarily be a physical process.
CS1104 Main Page
Last Updated 01/05/2000
© L.Heath, 2000