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
