Chapter 4
CPU-bound jobs (such as printing a series of documents) have many brief CPU cycles and long I/O cycles.
False
Dual core or quad core multi-core chips are larger than a single-processor chip but produce less current leakage and heat.
False
First-come, first-served (FCFS) is a preemptive scheduling algorithm that handles jobs according to their arrival time.
False
The Processor Manager is a composite of at least two submanagers: one in charge of job scheduling and the other in charge of program scheduling.
False
The control program that handles the interruption sequence of events is called the event scheduler.
False
The shortest remaining time (SRT) algorithm is often used in interactive systems.
False
When using priority scheduling, priorities are assigned to jobs by the owner of the job (the user).
False
The ____ is also called a high-level scheduler.
Job Scheduler
____ requires that the processor be allocated to each job or to each process for a period of time and deallocated at an appropriate moment.
Multiprogramming
The Process Scheduler assigns the CPU to execute the processes for those jobs placed on the ____ queue by the Job Scheduler.
READY
The transition from ____ can be initiated by the Process Scheduler or the Job Scheduler.
RUNNING to FINISHED
Each thread in a process is represented by a data structure called a ____ that contains basic information such as the thread's unique identification, state, and priority.
Thread Control Block
A processor is also known as a CPU.
True
A single processor can be shared by several jobs, or several processes, but only if the operating system has a scheduling policy, as well as a scheduling algorithm, to determine when to stop working on one job and proceed to another.
True
As a process moves through the system, its status changes. Possible process statuses include FINISHED, HOLD, READY, RUNNING, and WAITING.
True
Context switching is required by all preemptive algorithms.
True
If one job monopolizes the system, the extent of its overall effect on system performance depends on the scheduling policy and whether the job is CPU-bound or I/O-bound.
True
In Round Robin scheduling, if processing isn't finished when time expires, the job is preempted and put at the end of the READY queue and its information is saved in its Process Control Block.
True
It is possible to minimize response time by running only interactive jobs and letting batch jobs wait until the interactive load ceases.
True
Most computer programs alternate between CPU cycles and I/O cycles.
True
Shortest job next (SJN) is a nonpreemptive scheduling algorithm (also known as shortest job first, or SJF) that handles jobs based on the length of their CPU cycle time.
True
Web browsers use multithreading routinely. For example, one thread can retrieve images while another sends and retrieves e-mail.
True
When using a multiple-level queue strategy, aging is used to ensure that jobs in lower-level queues will eventually complete their execution.
True
The Job Scheduler seeks to ____ when scheduling jobs.
balance CPU and I/O intensive jobs
The first-come, first-served (FCFS) algorithm is fine for most ____ systems.
batch
No movement between queues is a very simple policy that rewards those who have ____ jobs.
high-priority
An I/O request is called a(n) ____ wait in multiprogramming environments.
natural
When the operating system detects a nonrecoverable error, the following step is performed first by the interrupt handler: ____.
the type of interrupt is described and stored
A(n) ____ is created by a process, and it can be scheduled and executed independently of its parent process.
thread
Assume that jobs A-D arrive in the READY queue in quick succession and have the CPU cycle requirements listed below. Using the SRT algorithm, the average turnaround time is ____.
6.25
Assume that jobs A-D arrive in the READY queue in quick succession and have the CPU cycle requirements listed below. Using the SRT algorithm, the average turnaround time is ____. Arrival time: 0 1 2 3 Job: A B C D CPU cycle: 6 3 1 4
6.25
A general rule of thumb for selecting a proper time quantum in Round Robin scheduling is that it should be long enough to allow ____ percent of the CPU cycles to run to completion.
80
Assume that four jobs, A-D, require the CPU cycles listed below. Using the SJN algorithm, the average turnaround time is ____. Job: A B C D CPU cycle: 5 2 6 4
9.0
Some systems use a strategy known as ____ to increase the priority of jobs that have been in the system for an unusually long time in order to expedite their exit.
Aging
Assume that four jobs, A-D, are in the READY queue at Time 0 and require the CPU cycles listed below. Using the SJN algorithm, the ____ job is run first. Job: A B C D CPU cycle: 5 2 6 4
B
____ is a dynamic-priority preemptive scheduling algorithm built to address the critical processing requirements of real-time systems and their pressing deadlines.
Earliest Deadline First
A job's state moves from HOLD to WAITING when it's ready to run but is waiting for the CPU.
False
A program is an active entity that requires a set of resources, including a processor and special registers, to perform its function.
False
When a job is accepted by the system, it's put on ____ and placed in a queue.
HOLD
The transition from ____ is initiated by the Job Scheduler according to some predefined policy. At this point, the availability of enough main memory and any requested devices is checked.
HOLD to READY
