CPU Scheduling Flashcards Preview

CMSC 125 Operating Systems > CPU Scheduling > Flashcards

Flashcards in CPU Scheduling Deck (37)
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1
Q

Basis for multiprogrammed OS which maximises CPU utilization

A

CPU scheduling

2
Q

Process execution which consists of a cycle of CPU execution and I/O wait

CPU burst (MAIN CONCERN) then I/O burst

A

CPU - I/O Burst Cycle

3
Q

This selects from among the processes in the ready queue and allocates one of them in the CPU

A

Short term scheduler

4
Q

CPU scheduling process takes place when a process

A
  • switch from running to waiting
  • switch from running to ready
  • switch from waiting to ready
  • terminate

(Nonpreemptive)

  • consider access to shared data
  • consider preemption while in kernel mode
  • consider interrupts during crucial OS activities

(Preemptive)

5
Q

Gives control of the CPU to the process selected by the short term scheduler which involves

  • switching contexts
  • switching to user mode
  • jumping to proper location in the user program to restart
A

Dispatcher module

6
Q

Time it takes for the dispatcher to stop one process and start another running

A

Dispatch latency

7
Q

Scheduling criteria which keeps the cpu busy at all times

A

CPU utilization

8
Q

Scheduling criteria which tracks the number of processes that complete their execution per time unit

A

Throughput

9
Q

Scheduling criteria which is the amount of time for a process to execute a particular process

A

Turnaround time

10
Q

Scheduling criteria which is the amount of time process has been waiting in the ready queue

A

Waiting time

11
Q

Scheduling criteria which is the amount it takes from when a request has been passed until the first response is produced

A

Response time

12
Q

A short process behind a long process

A

Convoy effect

13
Q

Ho to determine length of next cpu burst

A

Exponential averaging

14
Q

What is the problem of priority scheduling wherein LOW PRIORITY PROCESS MAY NEVER EXECUTE

A

Starvation

15
Q

Solution to the problem of priority scheduling wherein as time progresses, increase the prirority of the process

A

Aging

16
Q

A ready queue partitioned into ____ and ____

A

Multilevel queue

Foreground (interactive)
Background (batch)

17
Q

Scheduling algo of foreground and background

A

RR ; fcfs

18
Q

Scheduling between foreground and background

A
Fixed priority scheduling (foreground muna then background)
Time slice (80% foreground in rr & 20% background)
19
Q

Hierarchy of a multilevel queue scheduling

A
(Highest) system process
Interactive process
Interactive editing process
Batch process
Student process
20
Q

A process can move between queues in this type of queue where in processes cn be demoted or promoted to different queues

A

Multilevel feedback queue

21
Q

The thead library schedules USER LEVEL THREADS to run on lwp using PTHREAD_SCOPE _PROCESS

A

Process contention scope (local competition within process)

22
Q

Kernel thread scheduled ontonavailable cpu using PTHREAD_SCOPE_SYSTEM

A

System contention scope (competition among all threads)

23
Q

In a multiple processor scheduling, only one processor accesses the system data structures increasing the need for data sharing

A

Asymmetric multiprocessing

24
Q

In a multiple processor scheduling, each processor is self scheduled wherein all processes in common ready queue has its own private queue pr ready processes

A

Symmetric multiprocessing (smp)

25
Q

Types of processor affinity

A

Soft and hard affinity

Valiations incluing PROCESSOR SETS

26
Q

A way to keep efficiency of the CPU in SMP whrein trying to mainti=ain eben distributi9oon

A

Load balancing

27
Q

In smp, periodic tasks checks load on each processor and pushes task from overload cpu to other cou

A

Push migration

28
Q

In smp, idle processor pulls waiting task from busy processor

A

Pull migration

29
Q

A recent trend to place multiple processor cores on the same PHYSICAL CHIP which is FASTER AND CONSUMES LESS POWER

And multiple cores per thread also grows.
Execute another thread while memory stall is happening

A

Multicore processor

30
Q

A type of cpu scheduling where it can present obvious challenges

A

Real time cpu scheduling

31
Q

A type of realmtime cpu scheduling whrein there is no guarantee as tonwhen critical reak time process will be scheduled

A

Soft real time systems

32
Q

Task must be servicd by the deadline

A

Hard real time system

33
Q

A type of latency from ARRIVAL OF INTERRUPT to START OF ROUTINE that service the interrupt

A

Interrupt latency

34
Q

A type of latency which is the time for schedule to TAKE CURRENT PROCESS and SWITCH to another

A

Dispatch latency

35
Q

Priorities are assugned based in deadlines

A

Earliest deadline first (edf) scheduling

36
Q

How to select CPU scheduling algrithm for an os

A

Determine criteria and evaluate algorithm

37
Q

A type of ANALYTICAL EVAUATION wherein it takes a predetermined workloa and defines performance of each algorithm for that workload

A

Deterministic modeling