Operating Systems Concepts

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

race

In ____ systems, deadlocks can cause critical situations.

real-time

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 DCPU cycle: 5 2 6 4

9

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

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

Belday Anomaly

The key to the successful implementation of demand paging is the use of a high-speed CPU.

False

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

Compaction

With distributed operating systems, users need to be aware of which processor is actually running their applications.

False

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.

FIFO

General-purpose operating systems such as Linux or Windows are used in embedded systems.

False

In active multiprogramming schemes, a job can monopolize the CPU for a long time while all other jobs waited.

False

Single-user contiguous allocation schemes have the problem of partition intrusion.

False

Starvation is the result of a policy that liberally allocates resources.

False

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

False

The content of a random access memory (RAM) chip is nonvolatile, meaning that it is not erased when the power is turned off.

False

proposed a solution to the readers and writers problem that did not result in starvation for readers or writers.

Hoare

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

Main memory

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

Memory Map Table

Main memory is also known as ____.

Random Access Memory

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

Real-time

Fixed partitions are also called ____ partitions.

Static

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

Throughput

A large job can have problems with a first-fit memory allocation scheme.

True

A variation of the LRU page replacement algorithm known as the clock page replacement policy is implemented using a pointer to step through the reference bits of the active pages, simulating a clockwise motion.

True

In the bit-shifting variation of the LRU page replacement policy, the process of shifting bits to the right and resetting the leftmost bit to 1 when a page is referenced gives a history of each page's usage.

True

Memory defragmentation is performed by the operating system to reclaim fragmented space.

True

Most computer programs alternate between CPU cycles and I/O cycle

True

One of the problems with the best-fit algorithm is that the entire table must be searched before the allocation can be made because the memory blocks are physically stored in sequence according to their location in memory.

True

The Job Table (JT) contains two values for each active job: the size of the job and the memory location where its Page Map Table is stored.

True

The bounds register is used to store the highest (or lowest, depending on the specific system) location in memory accessible by each program.

True

The optimal selection of cache size and replacement algorithm can result in 80 to 90 percent of all requests being in the cache.

True

semaphores are used in the solution to the readers and writers problem that does not involve starvation.

Two

____ effectively removes restrictions on maximum program size.

Virtual memory

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 Job Scheduler seeks to ____ when scheduling jobs

balance CPU and I/O intensive jobs

A hybrid system is a combination of ____ systems.

batch and interactive

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.

bounds register

The source code of a Java program is first compiled into an intermediate language called Java ____, which are platform-independent.

bytecodes

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

cache memory

____ 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.

circular wait

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

cloud computing

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

mutual exclusion

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

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.

control unit

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

critical region

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.

device manager

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

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

external fragmentation

A race introduces the element of chance, which is a highly desirable attribute, in database management.

false

Each active thread in a process has its own processor registers, data area, and resources.

false

The master/slave configuration is a symmetric multiprocessing system.

false

The only tangible benefit of parallel processing systems is faster processing.

false

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.

firmware

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

first-fit memory allocation

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

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

holt

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

implicit parallelism

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

interrupt

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

natural

The ____ is also called a high-level scheduler.

job scheduler

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

loaded into memory

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

locality of reference

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

loosely coupled

The ____ multiprocessing configuration is an asymmetric system.

master/slave

What is the name traditionally given to a semaphore that enforces the concept of mutual exclusion?

mutex

____ 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

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

null entry

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.

overhead

The two operations defined by Dijkstra to be performed on a semaphore are ____.

p and v

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.

p1 requests r2, which is locked by p2

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

percentage

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

relocatable dynamic partitions

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

running to finished

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, ____

sales (P2) doesn't release the inventory file (F1) but requests the supplier file (F2)

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

segments

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

slots

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

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

swapped

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

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

the segment number and the displacement

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

there are two available

The Printer Event1 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. Assume that the events in the accompanying narrative take place. Which of the following statements is true?

there is no deadlock

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

thrashing

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

thread

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

semaphores are used in the producer and consumer problem.

three

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 ____.

time slicing

Fixing a deadlock situation requires outside intervention

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

Test-and-set is a single indivisible machine instruction. In a single machine cycle, it tests to see if a key is available and, if it is, sets it to unavailable.

true

____ allows for faster turnaround of CPU-bound jobs.

variable time quantum per queue

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

very long Page Map Tables

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

virtual memory

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

virtualization

When using the WAIT and SIGNAL operations, ____ sets the process's process control block to the blocked state and links it to the queue of processes waiting to enter this particular critical region.

wait