Operating Systems Final study guide
For a fixed partition system, memory deallocation is relatively complex.
False
In a loosely coupled system, a job may move from one processor to another during execution.
False
In the dining philosopher's problem, there are five philosophers and four forks.
False
Onboard systems are computers that are physically placed inside the products that they operate to add features and capabilities.
False
Single-user contiguous allocation schemes have the problem of partition intrusion.
False
The Memory Manager is in charge of main memory, widely known as ROM.
False
The best-fit allocation method keeps the free/busy lists organized by memory locations, low-order memory to high-order memory.
False
In a master/slave system, the master processor is responsible for managing the entire system—all files, devices, memory, and processors.
True
The fixed partition scheme works well when ____.
all jobs are of similiar size
The Banker's Algorithm is an example of a(n) ____ policy.
avoidance
____ 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
Failure to lock database records before updating them may result in a ____ between processes.
race
In ____ systems, deadlocks can cause critical situations.
real-time
Cache memory is divided into blocks of equal size called ____.
slots
To access a location in memory when using segmented memory management, the address is composed of two entries: ____.
the segment number and the displacement
____ developed the Banker's Algorithm
Dijkstra
With demand paging, if there are no empty page frames available, to move in a new page, one of the current resident pages must be placed into main memory.
False
When a job is accepted by the system, it's put on ____ and placed in a queue.
HOLD
The ____ is also called a high-level scheduler.
Job Schedular
One problem with the Banker's Algorithm is that because the algorithm assumes the worst case, vital resources can be unavailable in order to guard against unsafe states.
True
Single-user systems in a non-networked environment allocate, to each user, access to all available main memory for each job, and jobs are processed sequentially, one after the other.
True
The first attempt to allow for multiprogramming used fixed partitions.
True
When using the Banker's Algorithm, an operating system must be sure never to satisfy a request that moves it from a safe state to an unsafe one.
True
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
Memory compaction is also referred to as ____.
defragmentation
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 ____.
6.25
The ____ demonstrates that when using a FIFO policy, in rare cases, adding more memory to a system can cause an increase in page interrupts.
Belady Anomaly
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
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
A deadlock is preceded by the simultaneous occurrence of six conditions that the operating system (or other systems) could have recognized.
False
A job's working set is the collection of pages that must be loaded from secondary storage.
False
Compaction should always be performed only when there are jobs waiting to get in.
False
Deadlock does not usually affect the entire system.
False
Deadlock was a serious problem for early batch systems.
False
Each active thread in a process has its own processor registers, data area, and resources.
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 master/slave configuration is a symmetric multiprocessing system.
False
The optimal selection of cache size and replacement algorithm can result in 80 to 90 percent of all requests being in the cache.
False
The primary disadvantage of the WAIT and SIGNAL operation set is that it does not address busy waiting.
False
The shortest remaining time (SRT) algorithm is often used in interactive systems.
False
When a programmer indicates in the code which instructions can be executed in parallel in a program (for example, using COBEGIN and COEND), it is called implicit parallelism.
False
With distributed operating systems, users need to be aware of which processor is actually running their applications.
False
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
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.
Job Table
____ is where the data and instructions of a computer must reside to be processed.
Main Memory
The ____ multiprocessing configuration is an asymmetric system.
Master/slave
____ 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
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
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
A ____ chip holds software that is used to start the computer.
ROM
Main memory is also known as ____.
Random access memory
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
The transition from ____ can be initiated by the Process Scheduler or the Job Scheduler.
Running to Finished
In demand paging, pages are ____ between main memory and secondary storage.
Swapped
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.
True
Most computer programs alternate between CPU cycles and I/O cycles.
True
Multiprocessing can refer to one job using several processors to execute sets of instructions in parallel.
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 buffers used in the 1950s to reduce the discrepancy in speed between the I/O and the CPU were conceptually similar to those now used routinely by web browsers to make video and audio playback smoother.
True
The first bug was a moth trapped in a Harvard computer.
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.
True
The primary advantage of storing programs in a noncontiguos page frames (in a paged memory allocation scheme)is that main is used more efficiently because an empty page frame can be used by any page of any job.
True
Virtual memory can be implemented with both paging and segmentation.
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
____ allows separate partitions of a single server to support different operating systems.
Virtualization
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.
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
No movement between queues is a very simple policy that rewards those who have ____ jobs.
a high-priority
An algorithm designed to detect starvation by tracking how long each job has been waiting for resources is using the concept of ____.
aging
The goal of the ____ memory allocation algorithm is to find the smallest memory block into which a job will fit.
best fit
The purpose of cache memory is to keep handy the most recenly accessed data and instructions so that the CPU can access them repeatedly without wasting time. This purpose is similiar to that of the ___ of a web browser.
bookmark file
A variation of the LRU page replacement algorithm known as the ____ replacement policy is implemented with a circular queue.
clock page
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
In general, parallel systems can be put into two broad categories: ____ level parallelism and instruction level parallelism.
data
A disadvantage of segmented memory allocation is ____.
external fragmentation
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
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
____ 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
Most current operating systems support the implementation of threads, or ____, which have become part of numerous application packages.
lightweight processes
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
With the development of ____ technology, a single chip was equipped with two or more processor cores.
multicore
____ 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
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
Fixed partitions are also called ____ partitions.
static
The ____ multiprocessing configuration is the most difficult to implement because the processes must be well synchronized to avoid races and deadlocks.
symmetric
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 interupt is described and stored
In the "dining philosophers" problem, a philosopher can pick up a fork when ____.
there are two available
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 system with ____ divides programs into parts and keep them in secondary storage, bringing each part into memory only as it is needed.
virtual memory
One of the most important innovations of demand paging is that it makes ____ feasible.
virtual memory
