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Homework 2 Sarah Diesburg Operating Systems COP 4610
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Why does OS loader set kernel mode? OS needs to run with full privileges Sets more restrictive user mode bit for user programs Protects OS from errant user programs
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Three Processes Process A Process B Process C Time 0100200300400500600 700800
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First In, First Out Process A Process B Process C FIFO Time 0100200300400500600 700800 BCA
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First In, First Out Process A Process B Process C FIFO Average response time = [(300-50) + (500-150) + 0]/3 = 200 Time 0100200300400500600 700800 BCA
![First In, First Out Process A Process B Process C FIFO Average response time = [(300-50) + ( ) + 0]/3 = 200 Time BCA](http://images.slideplayer.com/14/4261866/slides/slide_5.jpg "First In, First Out Process A Process B Process C FIFO Average response time = [(300-50) + ( ) + 0]/3 = 200 Time BCA")
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First In, First Out Process A Process B Process C FIFO Average wait time = [(300-50) + (500-150) + 0]/3 = 200 Time 0100200300400500600 700800 BCA
![First In, First Out Process A Process B Process C FIFO Average wait time = [(300-50) + ( ) + 0]/3 = 200 Time BCA](http://images.slideplayer.com/14/4261866/slides/slide_6.jpg "First In, First Out Process A Process B Process C FIFO Average wait time = [(300-50) + ( ) + 0]/3 = 200 Time BCA")
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First In, First Out Process A Process B Process C FIFO Average turnaround time = [(500-50) + (900-150) + (300-0)]/3 = 500 Time 0100200300400500600 700800 BABCA
![First In, First Out Process A Process B Process C FIFO Average turnaround time = [(500-50) + ( ) + (300-0)]/3 = 500 Time BABCA](http://images.slideplayer.com/14/4261866/slides/slide_7.jpg "First In, First Out Process A Process B Process C FIFO Average turnaround time = [(500-50) + ( ) + (300-0)]/3 = 500 Time BABCA")
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Round Robin (Time slice = 100) Process A Process B Process C RR Time 0100200300400500600 700800 C
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 C
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CA
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CA
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CAC
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CAC
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACB
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACB
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBA
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBA
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBAC
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBAC
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBACB
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Process A Process B Process C RR Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBACB
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Process A Process B Process C RR Average response time = [(100-50) + (300 – 150) + 0]/3 = 66.7 Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBACB
![Process A Process B Process C RR Average response time = [(100-50) + (300 – 150) + 0]/3 = 66.7 Round Robin (Time slice = 100) Time CACBACB](http://images.slideplayer.com/14/4261866/slides/slide_22.jpg "Process A Process B Process C RR Average response time = [(100-50) + (300 – 150) + 0]/3 = 66.7 Round Robin (Time slice = 100) Time CACBACB")
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Process A Process B Process C RR Average wait time = {[(100–50) + (400–200)] + [(300–150) + (600–400)] + [0 + (200–100) + (500–300)]}/3 = [250 + 350 + 300]/3 = 300 Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBACB
![Process A Process B Process C RR Average wait time = {[(100–50) + (400–200)] + [(300–150) + (600–400)] + [0 + (200–100) + (500–300)]}/3 = [ ]/3 = 300 Round Robin (Time slice = 100) Time CACBACB](http://images.slideplayer.com/14/4261866/slides/slide_23.jpg "Process A Process B Process C RR Average wait time = {[(100–50) + (400–200)] + [(300–150) + (600–400)] + [0 + (200–100) + (500–300)]}/3 = [ ]/3 = 300 Round Robin (Time slice = 100) Time CACBACB")
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Process A Process B Process C RR Average turnaround time = [(500 – 50) + (900 – 150) + (600 – 0)]/3 = 600 Round Robin (Time slice = 100) Time 0100200300400500600 700800 CACBACB
![Process A Process B Process C RR Average turnaround time = [(500 – 50) + (900 – 150) + (600 – 0)]/3 = 600 Round Robin (Time slice = 100) Time CACBACB](http://images.slideplayer.com/14/4261866/slides/slide_24.jpg "Process A Process B Process C RR Average turnaround time = [(500 – 50) + (900 – 150) + (600 – 0)]/3 = 600 Round Robin (Time slice = 100) Time CACBACB")
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Shortest Job Next Process A Process B Process C SJN Time 0100200300400500600 700800 C
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Shortest Job Next Process A Process B Process C SJN Time 0100200300400500600 700800 C
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Shortest Job Next Process A Process B Process C SJN Time 0100200300400500600 700800 CA
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Shortest Job Next Process A Process B Process C SJN Time 0100200300400500600 700800 CA
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Shortest Job Next Process A Process B Process C SJN Time 0100200300400500600 700800 CA
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Shortest Job Next Process A Process B Process C SJN Time 0100200300400500600 700800 CAB
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Shortest Job Next Process A Process B Process C SJN Time 0100200300400500600 700800 CAB
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Shortest Job Next Process A Process B Process C SJN Average response time = [(300-50) + (500-150) + 0]/3 = 200 Time 0100200300400500600 700800 CAB
![Shortest Job Next Process A Process B Process C SJN Average response time = [(300-50) + ( ) + 0]/3 = 200 Time CAB](http://images.slideplayer.com/14/4261866/slides/slide_32.jpg "Shortest Job Next Process A Process B Process C SJN Average response time = [(300-50) + ( ) + 0]/3 = 200 Time CAB")
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Shortest Job Next Process A Process B Process C SJN Average wait time = [(300-50) + (500-150) + 0]/3 = 200 Time 0100200300400500600 700800 CAB
![Shortest Job Next Process A Process B Process C SJN Average wait time = [(300-50) + ( ) + 0]/3 = 200 Time CAB](http://images.slideplayer.com/14/4261866/slides/slide_33.jpg "Shortest Job Next Process A Process B Process C SJN Average wait time = [(300-50) + ( ) + 0]/3 = 200 Time CAB")
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Shortest Job Next Process A Process B Process C SJN Average turnaround time = [(500-50) + (900-150) + (300-0)]/3 = 500 Time 0100200300400500600 700800 CAB
![Shortest Job Next Process A Process B Process C SJN Average turnaround time = [(500-50) + ( ) + (300-0)]/3 = 500 Time CAB](http://images.slideplayer.com/14/4261866/slides/slide_34.jpg "Shortest Job Next Process A Process B Process C SJN Average turnaround time = [(500-50) + ( ) + (300-0)]/3 = 500 Time CAB")
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 C
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 C
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 CA
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 CA
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 CAC
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 CAC
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 CACB
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Shortest Remaining Time First Process A Process B Process C SRTF Time 0100200300400500600 700800 CACB
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Shortest Remaining Time First Process A Process B Process C SRTF Average response time = [0 + (500-150) + 0]/3 = 117 Time 0100200300400500600 700800 CACB
![Shortest Remaining Time First Process A Process B Process C SRTF Average response time = [0 + ( ) + 0]/3 = 117 Time CACB](http://images.slideplayer.com/14/4261866/slides/slide_43.jpg "Shortest Remaining Time First Process A Process B Process C SRTF Average response time = [0 + ( ) + 0]/3 = 117 Time CACB")
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Shortest Remaining Time First Process A Process B Process C SRTF Average wait time = [0 + (500 – 150) + (250 – 50)]/3 = 183 Time 0100200300400500600 700800 CACB
![Shortest Remaining Time First Process A Process B Process C SRTF Average wait time = [0 + (500 – 150) + (250 – 50)]/3 = 183 Time CACB](http://images.slideplayer.com/14/4261866/slides/slide_44.jpg "Shortest Remaining Time First Process A Process B Process C SRTF Average wait time = [0 + (500 – 150) + (250 – 50)]/3 = 183 Time CACB")
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Shortest Remaining Time First Process A Process B Process C SRTF Average turnaround time = [(250 – 50) + (900 – 150) + (500 – 0)]/3 = 483 Time 0100200300400500600 700800 CACB
![Shortest Remaining Time First Process A Process B Process C SRTF Average turnaround time = [(250 – 50) + (900 – 150) + (500 – 0)]/3 = 483 Time CACB](http://images.slideplayer.com/14/4261866/slides/slide_45.jpg "Shortest Remaining Time First Process A Process B Process C SRTF Average turnaround time = [(250 – 50) + (900 – 150) + (500 – 0)]/3 = 483 Time CACB")
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