CITC 1332 Midterm

P1 request R2, which is locked by P2

Fill in the missing event that causes deadlock in a database. There are two processes (P1 and P2), each of which needs to update two records (R1 and R2) and the following sequence leads to a deadlock: 1. P1 accesses R1 and locks it. 2. P2 accesses R2 and locks it. 3. ____ 4. P2 requests R1, which is locked by P1.

While the unit control 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

Fill in the missing event that causes livelock. 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.

Working Set

In demand paging, the collection of pages residing in memory that can be accessed directly without incurring a page fault is called the ____.

Thrashing

In demand paging, when an excessive number of pages are moved back and forth between main memory and secondary storage, it is called ____.

there are two available

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

Partition Size, Memory Address, Access, and Status

In the fixed-partition memory management scheme, the table that the Memory Manager uses to keep track of jobs is composed of the ____.

Random Access Memory (RAM)

Main memory is also known as ____.

Defragmentation

Memory compaction is also referred to as ____.

High-Priority

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

Percentage

One approach to performing compaction is to do it when a certain ____ of memory becomes busy.

Virtual Memory

One of the most important innovations of demand paging is that it makes ____ feasible.

Relocatable Dynamic Partitions

Single-user, fixed partition, and dynamic partition memory schemes share unacceptable fragmentation characteristics that were resolved with the development 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.

Control Unit

Starting in the 1950s, to reduce the discrepancy in speed between the I/O and the CPU, an interface called the ____ was placed between them to act as a buffer.

avoidance

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

Balance CPU and I/O Intensive Jobs

The Job Scheduler seeks to ____ when scheduling jobs.

There is no deadlock

The Printer Event 1 P1 requests and is allocated the printer R1. 2 P1 releases the printer R1. 3 P2 requests and is allocated the disk drive R2. 4 P2 releases the disk R2. 5 P3 requests and is allocated the plotter R3. 6 P3 releases the plotter R3. 12. Assume that the events in the accompanying narrative take place. Which of the following statements is true?

READY

The Process Scheduler assigns the CPU to execute the processes for those jobs placed on the ____ queue by the Job Scheduler.

Belady Anomaly

The ____ demonstrates that when using a FIFO policy, in rare cases, adding more memory to a system can cause an increase in page interrupts.

Job Scheduler

The ____ is also called a high-level scheduler.

User Interface

The ____ is often very different from one operating system to the next, sometimes even between different versions of the same operating system.

First-fit

The ____ memory allocation method keeps the free/busy lists organized by memory locations, from low-order memory to high-order memory.

FIFO

The ____ page replacement policy is based on the theory that the best page to remove is the one that has been in memory the longest.

Device Manager

The ____ uniquely identifies each resource, starts its operation,monitors its progress, and, finally, deallocates it, making the operating system available to the next waiting process.

Throughput

The efficiency of a batch system is measured in ____, which is the number of jobs completed in a given amount of time.

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

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

Multiuser

The first-come, first-served (FCFS) algorithm is fine for most ____ systems.

All Job Are of Similar Size

The fixed partition scheme works well when ____.

Loaded Into Memory

The four memory management techniques presented in this chapter share the requirement that the entire program being executed must be ____.

Best-fit

The goal of the ____ memory allocation algorithm is to find the smallest memory block into which a job will fit.

Interrupt

The most common mechanism for implementing multiprogramming was the introduction of the ____ concept, whereby the CPU was notified of events needing operating systems services.

Kernel

The name for the core portion of an operating system is the ____.

Internal Fragmentation

The phenomenon of less-than-complete use of memory space in a fixed partition is called ____.

Main Memory Is Used More Efficiently

The primary advantage of storing programs in noncontiguous locations is that ____.

Bookmark File

The purpose of cache memory is to keep handy the most recently accessed data and instructions so that the CPU can access them repeatedly without wasting time. This purpose is similar to that of the ____ of a Web browser.

Deallocation

The release of memory space by the Memory Manager is called ____.

Hierarchical ordering

The scheme of ____ removes the possibility of a circular wait and therefore guarantees the removal of deadlocks.

Locality of Reference

The term "____" means that during any phase of its execution, a program references only a small fraction of its pages.

RUNNING to FINISHED

The transition from ____ can be initiated by the Process Scheduler or the Job Scheduler.

HOLD to READY

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.

Firmware

The word ____ is used to indicate that a program is permanently held in ROM (read only memory), as opposed to being held in secondary storage.

Hard

There are two types of real-time systems depending on the consequences of missing the deadline. A ____ real-time system risks total system failure if the predicted time deadline is missed.

The Segment Number and The Displacement

To access a location in memory when using segmented memory management, the address is composed of two entries: ____.

HOLD

When a job is accepted by the system, it's put on ____ and placed in a queue.

Function

When reading an instruction, the operating system can tell the ____ of each group of digits by its location in the line and the operation code.

The Type of Interrupt is Described and Stored

When the operating system detects a nonrecoverable error, the following step is performed first by the interrupt handler: ____.

Find a process currently using a resource and not waiting for one

Which of the following is the first step in reducing a directed graph to eliminate deadlock?

Distributed

With ____ operating systems, users can think they are working with a system using one processor, when in fact they are connected to a cluster of many processors working closely together.

Segments

With segmented memory allocation, each job is divided into several ____ of different sizes, one for each module that contains pieces that perform related functions.

Multicore

With the development of ____ technology, a single chip was equipped with two or more processor cores.

Variable Time Quantum Per Queue

____ allows for faster turnaround of CPU-bound jobs.

Virtualization

____ allows separate partitions of a single server to support different operating systems.

Cache Memory

____ can be thought of as being an intermediary between main memory and the special-purpose registers, which are the domain of the CPU.

External Fragmentation

____ consists of fragments of free memory between blocks of allocated memory.

Dijkstra

____ developed the Banker's Algorithm.

Virtual Memory

____ effectively removes restrictions on maximum program size.

Earliest Deadline First

____ is a dynamic-priority preemptive scheduling algorithm built to address the critical processing requirements of real-time systems and their pressing deadlines.

Mutual exclusion

____ 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

____ is the policy of allowing only one process to have access to a dedicated resource.

Cloud Computing

____ is the practice of using Internet-connected resources to perform processing, storage, or other operations.

Circular wait

____ is when each process involved in an impasse is waiting for another to voluntarily release its resources so that at least one process will be able to continue.

Spooling

____ is when, in modern printing systems, a disk accepts output from several users and acts as a temporary storage area for all output until the printer is ready to accept it.

Main Memory

____ is where the data and instructions of a computer must reside to be processed.

Blocking

____ means that several logical records are grouped within one physical record.

Compaction

____ of memory is performed by the operating system to reclaim fragmented sections of the memory space.

Holt

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

Multiprogramming

____ requires that the processor be allocated to each job or to each process for a period of time and deallocated at an appropriate moment.

Real-time

____ systems are used in time-critical environments where reliability is key and data must be processed within a strict time limit.

ROM

A ____ chip holds software that is used to start the computer.

External Fragmentation

A disadvantage of segmented memory allocation is ____.

80

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.

Batch and Interactive

A hybrid system is a combination of ____ systems.

Virtual Memory

A system with ____ divides programs into parts and keep them in secondary storage, bringing each part into memory only as it is needed.

Clock Page

A variation of the LRU page replacement algorithm known as the ____ replacement policy is implemented with a circular queue.

Null Entry

A(n) ____ in the busy list occurs when a memory block between two other busy memory blocks is returned to the free list.

Thread

A(n) ____ is created by a process, and it can be scheduled and executed independently of its parent process.

Natural

An I/O request is called a(n) ____ wait in multiprogramming environments.

aging

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

B

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

9.0

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

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

Overhead

By compacting and relocating, the Memory Manager optimizes the use of memory and thus improves throughput. However, it also requires more ____ than the other memory allocation schemes discussed in this chapter.

Slots

Cache memory is divided into blocks of equal size called ____.

P2 doesn't release F1 but requests F2

Consider the case of a home construction company with two application programs, purchasing (P1) and sales (P2), which are active at the same time. They each need to access two files, inventory (F1) and suppliers (F2), to update daily transactions. The following series of events will cause a deadlock. Fill in the missing event in the sequence. 1. Purchasing (P1) accesses the supplier file (F2). 2. Sales (P2) accesses the inventory file (F1). 3. Purchasing (P1) doesn't release the supplier file (F2) and requests the inventory file (F1), but P1 is blocked because F1 is being held by P2. 4. Meanwhile, ____

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

Deadlock can occur on a printer when ____.

Device Driver

Each peripheral device has its own software, called a(n) ____, which contains the detailed instructions required to start that device, allocate it to a job, use the device correctly, and deallocate it when it's appropriate.

Thread Control Block

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.

Race

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

Time Slicing

In active multiprogramming, each program is allowed to use only a preset amount of CPU time before it is interrupted so another job can begin its execution. The interrupted job resumes execution at some later time. This idea is called ____.

Bound Register

In a relocatable dynamic partition scheme, the ____ ensures that, during execution, a program won't try to access memory locations that don't belong to it.

Sequentially

In a single-user system, jobs are processed ____.

Status Bit

In demand paging schemes, the ____ in a Page Map Table indicates whether the page is currently in memory.

Swapped

In demand paging, pages are ____ between main memory and secondary storage.

P2 request drive 2 and gets it

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.

Static

Fixed partitions are also called ____ partitions.

Real-time

In ____ systems, deadlocks can cause critical situations.

Very Long Page Map Tables

In a paged memory allocation scheme, a page size that is too small will generate ____.

Memory Map Table

In a paged memory allocation scheme, a simple ____ has one entry for each page frame that shows its location and its free/busy status.

Job Table

In a paged memory allocation scheme, the ____ contains two values for each active job: the size of the job and the memory location where its Page Map Table is stored.

Relocation Register

In a relocatable dynamic partition scheme, the ____ contains a value that must be added to each address referenced in a program so that the system will be able to access the correct memory addresses after relocation.