OS QUIZ 5
Which of the following parameters must be decided for a multilevel feedback queue scheduling algorithm? 1. number of feedback queues 2. entry criterion of a process to a specific queue 3. when to promote or demote processes from one queue to another 4. the scheduling algorithm for each queue
All of them
Why is this class so hard?
Because you lack the will to dedicate yourself to material that is even slightly challenging so you immediately lose interest and blame it the class being hard.
FCFS scheduling policy tends to favor I/O bound processes over CPU-bound processes.
False
It is not possible for a CPU scheduler to schedule processes based on their priority ranks and allowing them to run for a specific time quantum before giving chance to next process.
False
Explain the concept of "aging" in the context of CPU scheduling.
It is the solution to starvation because it raises the priority of a process the longer that it has been waiting in the ready queue.
Differentiate between process-contention scope (PCS) and system-contention scope (SCS) in thread scheduling
PCS allows thread scheduling within a process whereas SCS is thread scheduling at kernel level for all KTs
Which of the following scheduling algorithms is most difficult to implement for CPU scheduler of an OS? Round robin First-come-first-serve Shortest remaining-time first Priority
Shortest remaining-time first.
It is possible to make a round-robin scheduling practically a first-come-first-serve scheduling.
TRUE
Shortest job first (SJF) is basically a priority scheduling.
TRUE
Why certain scheduling algorithm suffers from "convoy effect"?
That stupid hoe didn't give me the answer.
Discuss two advantages of multi-queue feedback scheduling mechanism.
The process that is waiting long in a lower priority queue can be moved to a higher priority queue.
Which of the following algorithms is preemptive by nature in all circumstances? That is, there is no non-preemptive version of it. a.Round-robin b.First-come-first-serve c.Priority d.Shortest job first
a.Round-robin
Which scheduling algorithm guarantees best average waiting time for any set of processes? a.)Round robin b.)Shortest-job-first c.)First-come-first-serve d.)Priority
b.) shortest-job-first
Which of the following CPU scheduling algorithms is unlikely to create starvation of a process? a.)Shortest job first b.)Round robin c.)First-come-first-serve d.)Priority
b.)Round robin
Consider a preemptive priority scheduling algorithm based on dynamically changing priorities. Greater priority numbers imply higher priority. When a process is waiting for the CPU (in the ready queue, but not running), W is added to its priority value after each time unit. When it is running, R is added to its priority value after each time unit. All processes are given a priority of 0 when they enter the ready queue. Here, both R and W are positive with R > W. Indicate how the processes are scheduled in this scheme. a.)Last-in-first-served b.)Alternating between first waiting process and the new coming process c.)Round-robin with quantum (R-W) d.)First-come-first-served
d.)Fire-come-first-served
If there are 7 processes in the ready queue, number of possible schedules that can be created by a scheduler is _____. a.7 b.42 c.1 d.5040
d.5040
Suppose a CPU scheduler sets a fixed time quantum for all processes for a round-robin scheduling. The processes are ordered according to their priorities assigned by the OS and are allowed to run for the quantum, if needed. Which of the following would ensure lower average waiting time? a.)Assigning higher priorities to CPU-bound processes than I/O bound processes. b.)Assigning equal priorities to CPU-bound processes and I/O bound processes. c.)Setting time quantum sufficiently larger than average burst of CPU-bound processes. d.)Setting time quantum sufficiently smaller than average burst of I/O-bound processes. e.)Assigning higher priorities to I/O-bound processes than CPU-bound processes.
e.)Assigning higher priorities to I/O-bound processes than CPU bound processes.
