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Flashcards in cse4600 Exam 2 Deck (66):
1

What does PF stand for and what does it do?

Priority Function; The decision for which process will be allowed to execute

2

What does AR stand for and what does it do?

Arbitration Function; When two processes with equal priority are too be scheduled

3

What does DM stand for and what does it do?

Dynamic priority Measures; Parameters that change over time

4

Name some system measures that may determine priority level

external priority
total service time
deadline
real-time in the system
memory requirements

5

What is turnaround time

Total time between the submission of the process for execution and the return of the complete output

6

What is waiting time

amount of time a job is sitting ideal before the process is used

7

First in First out - Pros and Cons

Pro
- Easy to implement
- Ignores service time
Cons
- Not a great performer

8

First in First out PF

P = r, where r is the amount of real time

9

First in First out DM

Non - Preemptive

10

First in First out AR

random choice among processes arriving at exactly the same time

11

Shortest Job First PF

P = -t, where t is the total service time

12

Shortest Job First DM

Non - Preemptive

13

Shortest Job First AR

either chronological or random among processes with same service time

14

Shortest Remaining Time PF

P = - (t - a), where t-a is the remaining time

15

Shortest Remaining Time DM

Preemptive

16

Shortest Remaining Time AR

chronological or random among processes with same service time

17

Round Robin PF

P = 0, all processes have the same priority

18

Round Robin DM

preemptive quantum oriented

19

Round Robin AR

cyclic

20

Multilevel Priority PF

P = e

21

Multilevel Priority DM

preemptive if newly arriving process has a higher priority

within each priority queue, scheduling may be preemptive RR or non-preemptive FIFO

22

Multilevel Priority AR

cyclic if RR, random/chronological if FIFO

23

Multilevel Feedback PF

function of attained service time with different implementations possible

24

Multilevel Feedback DM

preemptive or non-preemptive; processes in the same level may use RR or FIFO

25

Multilevel Feedback AR

cyclic or random/chronological

26

Rate Monotonic PF

P = -d, where d is a fixed period of time that process needs to use the cpu

27

Rate Monotonic DM

preemptive

28

Rate Monotonic AR

random or chronological

29

Earliest Deadline First PF

P = -(d-r%d), where

r is the time since process first entered the system

d is its period

30

Earliest Deadline First DM

preemptive and dynamic

31

Earliest Deadline First AR

random or chronological

32

What is a time quantum

amount of timeshare (timeslice) given to each process, interrupting the job if it is not completed by then

33

What is throughput

the number of processes that are completed per time unit

34

What is response time

the time it takes to start responding, from the submission of the request until the first response is produced

35

What is turnaround time

from the time of submission of a process to the time of completion

36

What is waiting time

the sum of the periods spent waiting in the ready queue

37

What is burst time

the amount of time the process uses the processor before it is no longer ready

38

What is priority inversion

when a low priority process blocks a high priority process from executing because the low priority process is being preempted by a medium process

39

Shortest Job First - Pro

provably optimal, results in minimum average waiting time

40

Round Robin - Pro and Con

Pro
- better response than SJF
Con
- higher average turnaround

41

What is the equation for schedulability

n ( 2^1/n - 1 )

42

Primary use for Earliest Deadline First?

For real-time systems

43

When is a schedule feasible?

When all deadlines are satisfied

44

What is a method optimal?

If it always produces a feasible schedule if one exists

45

Rate Monotonic - Pros

- Simpler implementation
- Predicability for the highest priority

46

Earliest Deadline First - Pros

- Full processor utilizaiton
- Misbehavior during overload conditions

47

For Eventcount, what does await(E, v) do?

suspends the calling process if E < v; otherwise it allows the process to proceed

48

For Eventcount, what does advance(E) do?

eventcount value E is incremented and next process is admitted for service

49

For Eventcount, what does read(E) do?

inspects the current value of E

50

What does a monitors condition variable wait() do?

causes the executing process to be suspended on the queue

51

What does a monitors condition variable signal() do?

wakes up a process thats waiting on CV

52

What does a monitors condition variable queue() do?

true if queue is not empty, false if no process is waiting in the queue

53

For Mesa Semantics the thread that signals

keeps the lock

54

For Mesa Semantics the waiting thread

waits for the lock

55

For Hoare Semantics the thread that signals

gives up the lock and the waiting thread gets the lock

56

T/F: Hoare uses if rather than while

True

57

T/F: Mesa uses if rather than while

False

58

T/F: Monitors provide mutual exclusion between all procedures between shared data

True

59

For a producer/consumer problem why is
P(mutex)
P(full)
incorrect?

Because it will set Full variable and mutex variable to -1 and both Producer and Consumer will wait

60

What is a weak reader

an arriving writer waits until there are no more active readers

61

What is a strong reader

waiting reader has priority over a waiting writer

62

What is writer priority?

an arriving reader waits until there are no more active or waiting writers

63

Counting semaphores are used

to manage limited resources and corresponding access to them

64

Binary semaphores are usually used

to facilitate mutual exclusion

65

P(s) =

wait(s) = down(s)

66

V(s) =

signal(s) = up(s)