Basic Concepts

CPU - I/O Bursts

• CPU - I/O Burst cycles: where a process is executed followed by a I/O wait

• Of course this means that multiprogramming (2 processes at the same time) is optimal

CPU scheduler

• CPU picks a process in the ready queue and hands it over to a core

• Note: preemptive processes that access the same data, may lead to issues

List of all different scheduling states

Nonpreemptive - not ready now

• Running to waiting (waiting for an input)

• Terminate

Preemptive (baso will come back to it later, even-though it can still be run now) - ready now

• Running to ready (baso its ran out of time, so put in the ready queue)

• Waiting to ready (got its input, so is now the ready queue)

Dispatcher

• Gives control of the CPU to processes selected by the CPU schedular

• Dispatch Latency - the time required to stop one process and continue with another

Steps required to do this:

1. Switch context

2. Switching to user mode

3. Jumping to the location in the program where you last left it, to continue with the program