Concurrency (Scheduling)

Question 1

What is Race Condition

Answer 1

Threads&Processes are reading or writing shared data, which leads to results depending on the exact execution order of instructions
Solution: Introduction of critical sections and mutual exclusion

Question 2

What are the 3 scheduling problems?

Answer 2

Race conditions
Starvation
Priority inversion

Question 3

Nessessary conditions for the mutual exclusion

Answer 3

1. Only one process is allowed to enter the critical section
2. No assumption can be made about the speed and the amount of processors
3. No process is allowed to block another process outside the critical section
4. every process has only to wait a finite time to enter the critical section

Question 4

What is Starvation

Answer 4

a process is perpetually

Question 5

The different kinds of schedulings (8, 4 pairs)

Answer 5

preemptive / Non preemptive
static / dynamic
offline / online
optimal /heuristic

Question 6

What is Aperiodic Task

Answer 6

Irregular arrival times, either hard or soft deadlines, not cyclic

Question 7

What are the non-preemptive Scheduling (4)

Answer 7

• First Come First Served
• Shortest Job First
• Earliest Deadline First
• Earliest Start Time First