quiz 2

Fill in the missing step in the following deadlock situation. Two users from the local board of education are each running a program (P1 and P2), and both programs will eventually need two DVD drives to copy files from one disc to another. Only two DVD-R drives are available and they're allocated on an "as requested" basis. Soon the following sequence transpires: 1. P1 requests drive 1 and gets it. 2. ____ 3. P1 requests drive 2 but is blocked. 4. P2 requests drive 1 but is blocked.

P2 requests drive 2 and gets it.

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

The ____ multiprocessing configuration is the most difficult to implement because the processes must be well synchronized to avoid races and deadlocks.

Symetric

At an insurance company, the system performs many daily transactions. One day, the following series of events ties up the system: 1. Process P1 wishes to show a payment, so it issues a command to read the balance, which is stored in cylinder 20 of a disk pack. 2. ____ 3. P2 gains control of the I/O channel and issues a command to write someone else's payment to a record stored in cylinder 310. If the command is not "locked out," P2 will be put on hold while the control unit moves the arm to cylinder 310. 4. Because P2 is "on hold," the channel is free to be captured again by P1, which reconfirms its command to "read from cylinder 20." 5. Since the last command from P2 had forced the arm mechanism to cylinder 310, the disk control unit begins to reposition the arm to cylinder 20 to satisfy P1. The I/O channel would be released because P1 is once again put on hold, so it could be captured by P2, which issues a WRITE command only to discover that the arm mechanism needs to be repositioned.

While the control unit is moving the arm to cylinder 20, P1 is put on hold and the I/O channel is free to process the next I/O request.

An algorithm designed to detect starvation by tracking how long each job has been waiting for resources is using the concept of ____.

aging

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

The Banker's Algorithm is an example of a(n) ____ policy.

avoidance

A computer system that can support jobs that use multiple processors to execute sets of instructions in parallel is referred to as a ____ system.

concurrent processing

A ____ of processing must be handled as a single unit.

critical region

In general, parallel systems can be put into two broad categories: ____ level parallelism and instruction level parallelism.

data

____ published a visual tool to show how deadlock conditions can be modeled using directed graphs.

havender

No movement between queues is a very simple policy that rewards those who have ____ jobs.

high-priority

When a compiler automatically detects instructions that can be performed in parallel, ____ is in place.

implicit parrallelism

The ____ is also called a high-level scheduler.

job scheduler

Most current operating systems support the implementation of threads, or ____, which have become part of numerous application packages.

lightweight processess

The ____ multiprocessing configuration features several complete computer systems, each with its own memory, I/O devices, CPU, and operating system.

loosely coupled

Lock and key synchronization must take place within a single ____.

machine cycle

The ____ multiprocessing configuration is an asymmetric system.

master/slave

____ 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

____ is necessary in any computer system because some resources such as memory, CPU, and dedicated devices must be exclusively allocated to one user at a time.

mutual exclusion

Failure to lock database records before updating them may result in a ____ between processes.

race

In ____ systems, deadlocks can cause critical situations.

real-time

A problem with test-and-set is that when many processes are waiting to enter a critical region, ____ can occur because the processes gain access in an arbitrary fashion.

starvation

The first and simplest recovery method, and the most drastic, is to ____.

terminate every job that's active in the system and restart them from the beginning

The operation P in a semaphore scheme requires a(n) ____ sequence to be performed as an indivisible action in a single machine cycle.

test, fetch, decrement, and store

Deadlock can occur on a printer when ____.

the printer needs all of a job's output before it will begin printing, but the spooling system fills the available disk space with only partially completed output

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

In the "dining philosophers" problem, a philosopher can pick up a fork when ____.

there are two available

In its simplest form, Amdahl's Law maintains that if a given program would take one hour to run to completion with one processor, but 80 percent of the program had to run sequentially (and therefore could not be sped up by applying additional processors to it), then a resulting parallel program would run only a maximum of ____ percent faster.

20

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

____ developed the Banker's Algorithm

Dijkstra

____ 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

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