Chapter 6 (Quiz 4 Portion) Flashcards
CPU Scheduling, Basic Concepts, Scheduling Criteria, Scheduling Algorithms, Thread Scheduling, Multiple-Processor Scheduling, Real-Time CPU Scheduling, Operating Systems Examples, Algorithm Evaluation.
When does CPU scheduling decisions take place?
1- Switching from running to waiting state.
2- Switching from running to ready state.
3- Switching from waiting to ready.
4- Terminates.
what is “Non-preemptive”?
The process from 1 to 4, the process cannot be interrupted has to run until the end.
What is “Preemptive”?
The process from 5 and up, in the ready queue.
What are the details of Preemptive?
1- Shared data.
2- Kernel mode.
3- Interrupts during crucial OS activities.
What is the “Dispatcher Module”?
Gives control of the CPU to the process selected by the short-term scheduler.
What does the Dispatcher Module involve?
1- Switching context.
2- Switching to user mode.
3- Jumping to the location in the user program to restart that program.
What is “Dispatch lantency”?
Time it takes for the dispatcher to stop one process and start another running.
What are the CPU scheduling criteria?
1- CPU utilization.
2- Throughput.
3- Turnaround time.
4- Waiting time.
5- Response time.
What is “CPU utilization”?
keep the CPU as busy as possible.
What is “Throughput”?
number (#) of processes that complete their execution per time unit.
What is “Turnaround time”?
amount of time to execute a particular process.
What is “Waiting time”?
amount of time a process has been waiting in the ready queue.
What are the CPU scheduling algorithm optimization criteria?
1- Max CPU utilization.
2- Max Throughput.
3- Min Turnaround time.
4- Min Waiting time.
5- Min Response time.
What is “Starvation” in CPU Priority Scheduling?
Low priority processes may never execute.
What is “Aging” in CPU Priority Scheduling?
As time progresses increase the priority of the process.
What are the difference of “foreground” & “background” of Multilevel Queue?
Foreground :-
1- Interactive.
2- Uses RR. (Round Robin)
3- Uses 80% of the system.
Background :-
1- Batch.
2- Uses FCFS. (First- Come, First-Served)
3- Uses 20% of the system.
What is “Load balancing”?
Attempts to keep workload evenly distributed.
What is “Push migration”?
Periodic task checks load on each processor, and if found pushes task from overloaded CPU to other CPU’s.
What is “Pull migration”?
Idle processors pulls waiting task from busy processor.
What is “Soft real-time systems”?
No guarantee as to when critical real-time process will be scheduled.
What is “Hard real-time systems”?
Task must be serviced by its deadline.
