General:
1. What devices do you own with operating systems (smartphones, tablets, computers). For each (up to 3): (5 points)
a. What OS does it run? What version? What is the update mechanism?
Answer) my computer OS is windows 8 and my smartphone OS is IOS 7. Windows update mechanism is Windows Updates and IOS update mechanism is ITunes.
Chapter 2
2. What is the main advantage for an operating-system designer of using a virtual-machine architecture? What is the main advantage for a user? (10 points)
Answer) OS designers can solve debug, network problem and security problem easily.
Users also can undergo many different OS on one physical system. It is easy to research and develop.

Chapter 3
3. Discuss three major complications concurrent processing adds to an OS. (10 points)
Answer) 1. Processes and system resources should protected from each other. 2. More than one process executing concurrently for protect performance degradation 3. It occurs deadlocks. So you can m

Chapter 4:
4. Provide a programming example where multithreading does not provide better performance than a single-threaded solution. (5 points)
Answer) Sequential program is not good at threaded. So example is Shell program.

5. Can a multithreaded solution using multiple user-level threads achieve better performance on a multiprocessor system than on a single-processor system? How does this change if kernel-level threads are used? Explain. (10 points)
Answer) multiple user-level threads cannot make different processors in multiprocessor system at the same time. So, it shows lower performance. But If change kernel-level threads, it can make different processors at the same time. It is good at multiprocessor system

Chapter 5 complications
6. Discuss how the following pairs of scheduling criteria conflict in certain settings. (15 points)
a. CPU utilization and response time
Answer) CPU utilization should increase with minimized of context switching. If context switching is maximized, response time will increase.

b. Average turnaround time and maximum waiting time
Answer) Shortest tasks provide short turnaround time and waiting time will decrease. But long-running tasks provide long turnaround time and waiting time will increase

c. I/O device utilization and CPU utilization
Answer) I/O-bound give bed effect to I/O device utilization and bed I/O device utilization give bed effect to CPU utilization.

7. Consider the following set of processes, with the length of the CPU-burst time given in milliseconds: (15 points)
Process Burst Priority
P1 12 3
P2 1 1
P3 2 3
P4 1 4
P5 4 2
a. Draw four Gantt charts illustrating the execution of these processes using FCFS, SJF, nonpreemptive priority (a smaller priority number implies a higher priority), and RR (quantum = 1) scheduling.
Answer) 1. FCFS
| P1 | P2 | P3 | P4 | P5 |
0 12 13 15 16 20

2. SJF
| P2 | P4 | P3 | P5 | P1 |
0 1 2 4 8 20

3. Nonpremptive priority
| P2 | P5 | P1 | P3 | P4 |
0 1 5 17 19 20

4. RR
| P1 | P2 | P3 | P4 | P5 | P1 | P3 | P5 | P1 | P5 | P1 | P5 | P1 |
0 1 2 3 4 5 6 7 8 9 10 11 12 20
b. What are the turnaround time and waiting time of each process for each of the algorithms above?
1. FCFS Turnaround time Waiting Time
P1 12 0
P2 13 12
P3 15 13
P4 16 15
P5 20 16

2. SJF Turnaround time Waiting Time
P1 20 8
P2 1 0
P3 4 2
P4 2 1
P5 8 4

3. Nonpremptive priority Turnaround time Waiting Time
P1 17 5
P2 1 0
P3 19 17
P4 20 19
P5 5 1

4. RR Turnaround time Waiting Time
P1 20 8
P2 2 1
P3 7 5
P4 4 3
P5 12 8

c. Which algorithm yields minimum average waiting time (over all processes)?
Average waiting time
FCFS 11.2
SJF 3
Non P 8.4
RR 5 Answer) So, SJF (Shortest Job First) is shortest average waiting time on the algorithm