CS-360 Operating Systems Exam 1

Assume that four page frames are available and are numbered 1-4. Pages A-D have been loaded into page frames 1-4 in order. The program has accessed the pages in the following order: B, D, A, C. Assume that page E is requested. The ____ page frame will be loaded when the LRU algorithm is used.

2

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 2 2 3 Job: A B C D CPU cycle: 6 2 1 5

6

The cache hit ratio is ____, if the total number of requests is 10 and 6 of those are found in cache memory.

60%

If a particular demand paging configuration has 9 page interrupts out of 11 page requests, failure rate is ____.

82%

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.(T/F)

True

After relocation and compaction, both the free list and the busy list are updated.(T/F)

True

An important function of the Processor Manager is to keep track of the status of each job, process, and thread.(T/F)

True

As a process moves through the system, its status changes. Possible process statuses include HOLD, READY, RUNNING, WAITING, and FINISHED.(T/F)

True

Associative memory is a name given to several hardware registers that are allocated to each active job whose task is to associate segment and page numbers belonging to the job being processed with their main memory addresses.(T/F)

True

Context switching is required by all preemptive algorithms.(T/F)

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. (T/F)

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.(T/F)

True

In a dynamic partition system, a null entry in the busy list occurs when a memory block between two other busy memory blocks is returned to the free list.(T/F)

True

In the relocatable dynamic partitions scheme, the Memory Manager relocates programs to gather together all of the empty blocks and compact them to make one block of memory large enough to accommodate some or all of the jobs waiting to get in.(T/F)

True

It is possible to minimize response time by running only interactive jobs and letting batch jobs wait until the interactive load ceases.(T/F)

True

Memory defragmentation is performed by the operating system to reclaim fragmented space.(T/F)

True

Most computer programs alternate between CPU cycles and I/O cycles.(T/F)

True

Networking was not always an integral part of operating systems.(T/F)

True

Research continues to focus on finding the optimum allocation scheme.(T/F)

True

The Device Manager is responsible for connecting with every device that's available on the system and for choosing the most efficient way to allocate them.(T/F)

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.(T/F)

True

The algorithm used to store jobs into memory in a fixed partition system requires a few more steps than the one used for a single-user system because the size of the job must be matched with the size of the partition to make sure it fits completely.(T/F)

True

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

True

The fixed partition scheme works well if all of the jobs run on the system are of the same size or if the sizes are known ahead of time and don't vary between reconfigurations.(T/F)

True

The operating system manages each and every piece of hardware and software.(T/F)

True

The primary advantage of storing programs in noncontiguous page frames (in a paged memory allocation scheme) is that main memory is used more efficiently because an empty page frame can be used by any page of any job.(T/F)

True

The shortest remaining time (SRT) algorithm is not recommended for interactive systems.(T/F)

True

Virtual memory can be implemented with both paging and segmentation.(T/F)

True

Web browsers use multithreading routinely. For example, one thread can retrieve images while another sends and retrieves e-mail. (T/F)

True

When using a multiple-level queue strategy, aging is used to ensure that jobs in lower-level queues will eventually complete their execution.(T/F)

True

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

User Interface

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

first-fit memory allocation

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.

hard

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

internal fragmentation

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

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

kernel

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

main memory is used more efficiently

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

multicore

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

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

partition size, memory address, access, and status

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.

relocation register

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 1

D

A hybrid system is a combination of ____ systems.

batch and interactive

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

best-fit

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 Memory Manager is in charge of main memory, widely known as ROM.(T/F)

False

The Memory Manager, the Interface Manager, the User Manager, and the File Manager are the four essential managers of every major operating system.(T/F)

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.(T/F)

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

The control program that handles the interruption sequence of events is called the event scheduler. (T/F)

False

The first-fit algorithm assumes that the Memory Manager keeps only one list containing free memory blocks.(T/F)

False

The key to the successful implementation of demand paging is the use of a high-speed CPU.(T/F)

False

When using priority scheduling, priorities are assigned to jobs by the owner of the job (the user).(T/F)

False

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

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

sequentially

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

thrashing

When there is an excessive amount of page swapping between main memory and secondary storage, the operation becomes inefficient, which is called ____.

thrashing

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

throughput

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

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

working set

Consider the following page fault handler algorithm. Replace the * in the algorithm with ____. 1 If there is no free page frame Then select page to be swapped out using page removal algorithm update job's Page Map Table If content of page had been changed then * End if End if 2 Use page number from step 3 from the Hardware Instruction Processing Algorithm to get disk address where the requested page is stored 3 Read page into memory 4 Update job's Page Map Table 5 Update Memory Map Table 6 Restart interrupted instruction

write page to disk

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

ROM

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

Real-time

In a demand paging scheme, the first-in first-out (FIFO) page replacement policy chooses the page least recently accessed to be swapped out.(T/F)

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

A job's state moves from HOLD to WAITING when it's ready to run but is waiting for the CPU.(T/F)

False

A job's working set is the collection of pages that must be loaded from secondary storage.(T/F)

False

A program is an active entity that requires a set of resources, including a processor and special registers, to perform its function.(T/F)

False

CPU-bound jobs (such as printing a series of documents) have many brief CPU cycles and long I/O cycles.(T/F)

False

Compaction should always be performed only when there are jobs waiting to get in.(T/F)

False

Dual core or quad core multi-core chips are larger than a single-processor chip but produce less current leakage and heat.(T/F)

False

Assume that four jobs, A-D, arrived at the same time and the require the CPU cycles listed below. Using the SJN algorithm, the average turnaround time is ____. Job: A B C D CPU cycle: 5 3 6 4

10.0

First-come, first-served (FCFS) is a preemptive scheduling algorithm that handles jobs according to their arrival time.(T/F)

False

Consider the following four cases. The LRU policy,____, will be lease likely to swap. Modified Referenced Meaning Case 1 0 0 Not modified AND not referenced Case 2 0 1 Not modified BUT was referenced Case 3 1 0 Was modified BUT not referenced Case 4 1 1 Was modified AND was referenced

Case 4

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

Cloud computing

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

Compaction

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

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

A disadvantage of segmented memory allocation is ____.

external fragmentation