C191 Practice quiz

What does each entry in the page table contain?

A page number and a frame number.

_____ is the dynamic storage allocation algorithm that results in the smallest leftover hole in memory.

Best-fit

What is described as memory allocated from a fixed-size segment consisting of physically contiguous pages?

Buddy system

A ________ is an example of a systems program.

Command interpreter.

What will collect free space (i.e., garbage collection) together to provide more usable space?

Compaction

Which memory management solution relocates all available memory into one variable-sized block?

Compaction

Which features are included in the DTrace tool?

Compiler, providers of probes, and consumers

What is the name of the default scheduling algorithm for current Linux systems?

Completely Fair Scheduler (CFS)

________ is not considered a challenge when designing applications for multicore systems.

Ensuring there is a sufficient number of cores

Which service function is responsible for identifying and correcting exceptions such as the lack of paper in a printer?

Error detection

What is a stored data condition that can prevent other processes from gaining access to it?

File locking

_________ is a thread library for Solaris that maps many user-level threads to one kernel thread.

Green threads.

Which of the following is true of the direct access method?

It allows programs to read and write records in no particular order.

______ allows a portion of a virtual address space to be logically associated with a file.

Memory mapping

What is the mode of system during boot time?

Kernel mode

What is the mode of the system when the operating system gains control?

Kernel mode

What is the difference between kernel and user threads?

Kernel threads are directly managed by the operating system, whereas user threads are managed without kernel support.

_____ is the algorithm implemented on most systems.

LRU

What page replacement algorithm is used by Windows

Least Recently Used (LRU)

What is a scheme used to help free up space (i.e. garbage collection)?

Least frequently used (LFU)

What does the 50-percent rule of memory fragmentation state when allocating additional memory using the first-fit method?

One-third of all memory may be unused.

What principle dictates that programs and users be given just enough privileges to perform their tasks?

Principle of Least Privilege

_______ is/are not a technique for managing critical sections in operating systems.

Peterson's solution

How do policies and mechanisms differ?

Policies may change from place to place whereas mechanisms remain the same.

What is the term for a program that has been loaded and is executing?

Process

__________ allows a thread to run on only one processor.

Processor affinity

What are the names of the two processes associated with the bounded-buffer problem?

Producer, consumer

Which OS service provides functions that are helpful to the user?

Program execution

_________ involves distributing tasks across multiple computing cores.

Task parallelism

What is considered stable when the average rate of process creation is equal to the average departure rate of processes leaving the system?

The degree of multiprogramming

Which of the following statements is false?

The difference in storage capacity between a mobile device and laptop is shrinking.

Which of the following data structures is appropriate for placing into its own segment?

- heap - kernel code and data - user code and data

Provide at least three resources the operating system allocates

1. CPU 2. Memory 3. I/O devices

List at least three different criteria for designing a CPU scheduling algorithm.

1. CPU utilization 2. Throughput 3. Turnaround *4. Waiting time *5. Response time

List at least three operations that may be performed on a file.

1. Create a file 2. Write to a file 3. Read a file

What are the two general types of parallelism?

1. Data parallelism2. Task parallelism

Describe one strategy for dealing with deadlocks?

1. Deadlocks Prevention/Avoidance - use a protocol to prevent or avoid deadlocks, effectively ensuring that the system will NEVER enter a deadlocked state 2.Deadlock detection and recovery 3. Ignore the potential for deadlocks and rely on means of manual recovery in the event that a deadlock happens

Consider a logical address with 18 bits used to represent an entry in a conventional page table. How many entries are in the conventional page table?

262144

In capability lists, each object has a ____ to denote its type.

tag

The Linux CFS scheduler identifies _____________ as the interval of time during which every runnable task should run at least once.

targeted latency

A(n) ____ is a front-end processor that multiplexes the traffic from hundreds of remote terminals into one port on a large computer

terminal concentrator

A microkernel is a kernel _______.

that is stripped of all nonessential components.

In a paired-password system, ____.

the computer supplies one part of a password and the user enters the other part

In the UNIX operating system, a domain is associated with the ____.

user

The two separate modes of operating in a system are

user mode and kernel mode

Which of the following statements is false with regard to Solaris memory management?

The speed at which pages are examined (the scan rate) is constant.

Which scheduling criteria measures the number of processes completed per time unit?

Throughput

What is a valid process state?

Waiting

The major difficulty in designing a layered operating system approach is ______

appropriately defining the various layers.

If a program terminates abnormally, a dump of memory may be examined by a _______ to determine the cause of the problem.

debugger.

Cancellation points are associated with ______ cancellation.

deferred

On media that uses constant linear velocity, the ____.

density of bits per track is uniform

A message-passing model is _______

easier to implement than a shared memory model for intercomputer communication.

A ________________ saves the state of the currently running process and restores the state of the next process to run.

context switch

Which of the following allocation methods ensures that only one access is needed to get a disk block using direct access?

contiguous allocation

In an access matrix, the ____ right allows a process to change the entries in a row.

control

The ____ register of an I/O port can be written by the host to start a command or to change the mode of a device.

control

In Peterson's solution, the ______ variable indicates if a process is ready to enter its critical section.

flag[i]

Belady's anomaly states that ____.

for some page replacement algorithms, the page fault rate may increase as the number of allocated frames increases

The windows CreateProcess() system call creates a new process. What is the equivalent system call in UNIX?

fork()

A clustered system ______.

gathers together multiple CPUs to accomplish computational work.

The ____ implementation of an access table consists of sets of ordered triples.

global table

A(n) ____ page table has one page entry for each real page (or frame) of memory.

inverted

The file-allocation table (FAT) used in MS-DOS is an example of _____.

linked allocation

Which of the following implementations of the access matrix is a compromise between two other implementations listed below?

lock-key

An address generated by a CPU is referred to as a ____.

logical address

What must be done to a disk before it can be used for storage?

low-level formatting (AKA physical formatting)

The most common secondary storage device is ________

magnetic disk.

The most common method used by attackers to breach security is ____.

masquerading

Microkernels use ______ for communication.

message passing.

The Windows CreateFile() system call is used to create a file. What is the equivalent system call in UNIX?

open()

In systems that support virtual memory, ____.

physical memory is separated from logical memory

Grand Central Dispatch (GCP) handles blocks by _______.

placing them on a dispatch queue

A ____ virus changes each time it is installed to avoid detection by antivirus software.

polymorphic

Which criterion attempts to keep the processor as busy as possible?

CPU utilization

What is memory-mapped I/O?

Memory addresses reserved for device registers

A blocking send() and blocking receive() is known as a(n) ______________

rendezvous

The simplest file access method is ____.

sequential access

An interrupt priority scheme can be used to ____.

- Allow the most urgent work to be finished first - Make it possible for high-priority interrupts to preempt the execution of a low priority interrupt - defer the handling of a low-priority interrupt without masking off all interrupts

What are two key types of access permissions?

- Append - List

A process may transition to the Ready state by which of the following actions?

- Completion of an IO event - Awaiting its turn on the CPU - Newly-admitted process

Which of the following would be an acceptable signal handling scheme for a multithreaded program?

- Deliver the signal to the thread to which the signal applies. - Deliver the signal to every thread in the process. - Deliver the signal to only certain threads in the process.

What are some other terms for kernel mode?

- Supervisor mode. - System mode - Privileged mode.

When a child process is created, which of the following is a possibility in terms of the execution or address space of the child process?

- The child process runs concurrently with the parent. - The child process has a new program loaded into it. - The child is a duplicate of the parent.

What are two valid components of a process control block (PCB)?

- The process counter - The process state

What can be assigned roles when using role-based access control?

- The program - The process

Worms ____.

- use the spawn mechanism to ravage system performance - can shut down an entire network - continue to grow as the Internet expands

Given the logical address 0xAEF9 (in hexadecimal) with a page size of 256 bytes, what is the page offset?

0xF9

List the three general disk scheduling algorithms

1. FCFS (first come first serve) 2. SSTF (shortest seek time first) 3. SCAN (starts at one end and moves to the other, reversing back when it gets to each end)

What are the three strategies for selecting a free hole from the set of available hole?

1. First fit - allocate the first hole that is big enough 2. Best fit - allocate the smallest hole that is big enough 3. Worst fit - allocate the largest hole available.

Name one type of remote file system

1. NFS *2. CIFS/SMB *3. WebDAV

What are the two types of pipes?

1. Ordinary Pipes 2. Named Pipes

What are the two fundamental ways of accessing a file?

1. Sequential Access - process information in the file one record after another. 2. Direct Access (AKA Relative Access) - Read and write logical records rapidly in no particular order.

What are the four components of a computer system?

1. hardware 2. operating system 3. application programs 4. users

What two registers can be used to provide a simple form of memory protection?

1. relocation register2. limit register

What are the two general types of real-time scheduling?

1. soft real-time systems2. hard real-time systems

Consider a logical address with a page size of 8 KB. How many bits must be used to represent the page offset in the logical address?

13

Imagine that a host with IP address 150.55.66.77 wishes to download a file from the web server at IP address 202.28.15.123. Select a valid socket pair for a connection between this pair of hosts.

150.55.66.77:2000 and 202.28.15.123:80

Suppose a program is operating with execution-time binding and the physical address generated is 300. The relocation register is set to 100. What is the corresponding logical address?

200

What is the average latency of a typical hard disk?

3 milliseconds

Suppose we have the following page accesses: 1 2 3 4 2 3 4 1 2 1 1 3 1 4 and that there are three frames within our system. Using the FIFO replacement algorithm, what will be the final configuration of the three frames following the execution of the given reference string?

3, 4, 2

RAID level ____ is the most common parity RAID system.

5

What size segment will be allocated for a 39 KB request on a system using the buddy system for kernel memory allocation?

64 KB

Suppose we have the following page accesses: 1 2 3 4 2 3 4 1 2 1 1 3 1 4 and that there are three frames within our system. Using the LRU replacement algorithm, what is the number of page faults for the given reference string?

8

Consider a disk queue holding requests to the following cylinders in the listed order: 116, 22, 3, 11, 75, 185, 100, 87. Using the SSTF scheduling algorithm, what is the order in which the requests are serviced, assuming the disk head is at cylinder 88 and moving upward through the cylinders?

87 - 75 - 100 - 116 - 185 - 22 - 11 - 3

Consider a 32-bit address for a two-level paging system with an 8 KB page size. The outer page table has 1024 entries. How many bits are used to represent the second-level page table?

9

What is Beowulf Cluster?

A Beowulf cluster consists of commodity hardware (such as personal computers) connected via a simple local-area network. No single specific softwood package is required to construct a cluster. The nodes use a set of open-sources software libraries to coordinate and communicate with one another

What is an address that is generated by the CPU?

A logical address

In Windows, what represents the shared-memory object that will enable communication between processes?

A memory-mapped file

Child processes inherit UNIX ordinary pipes form their parent process because:

A pipe is treated as a file descriptor and child processes inherit open file descriptors from their parents

Which of the following is an advantage of compiler-based enforcement of access control?

Access privileges are closely related to the linguistic concept of a data type.

Which system calls can be grouped under the category of process controls?

Allocate, free memory

What is a volume

Any entity containing a file system.

What is a limitation of swapping on mobile systems?

Applications that fail to free up sufficient memory are terminated.

Which of the following statements is false with regard to allocating kernel memory?

Because the kernel requests memory of varying sizes, some of which may be quite small, the system does not have to be concerned about wasting memory.

What is the smallest unit of data transfer in a physical hard disk drive?

Block

Several major retail chains are hacked and customer information is stolen, including credit card numbers. Which type of attack has occurred?

Breach of confidentiality

How can protection improve the reliability of a system?

By detecting errors at the interfaces between component subsystems

_______ is/are not a technique for passing parameters from an application to a system call.

Cache memory

What is a disadvantage of booting an OS stored in ROM?

Changing a bootstrap requires new hardware chips.

Which mounting model allows a computer to mount file systems from remote machines?

Client-server

Which of the following is a property of peer-to-peer systems?

Clients and servers are not distinguished from one another.

The close() system call in UNIX is used to close a file. What is the equivalent system call in Windows?

CloseHandle()

Assume an adaptive mutex is used for accessing shared data on a Solaris system with multiprocessing capabilities. Which of the following statement is not true?

Condition variables and semaphores are never used in place of an adaptive mutex.

Which action allows an application that is in the background to be passed to the foreground and vice versa?

Context switching

What is the difference between cooperative and preemptive scheduling?

Cooperative scheduling occurs when a process terminates, whereas preemptive scheduling occurs when a process initiates.

________ allows the parent and child processes to initially share the same pages, but when either process modifies a page, a copy of the shared page is created.

Copy-on-write

Which of the following statements is true?

Counting semaphores can be used to control access to a resource with a finite number of instances.

What is the Windows API for creating a thread?

CreateThread()

Which of the following would lead you to believe that a given system is an SMP-type system?

Each processor performs all tasks within the O.S

Which of the following is true of multilevel queue scheduling?

Each queue has its own scheduling algorithm.

Which of the following is a true statement regarding the relative merits between access rights enforcement based solely on a kernel, as opposed to enforcement provided largely by a compiler?

Enforcement by the kernel is less flexible than enforcement by the programming language for user-defined policy.

_____ is the method of binding instructions and data to memory performed by most general-purpose operating systems.

Execution time binding

What disk scheduling algorithm is typically used with SSDs?

FCFS

Which of the following disk head scheduling algorithms does not take into account the current position of the disk head?

FCFS

Which component is associated with the paging scheme?

Frames

What is a difference between soft and hard processor affinity?

Hard affinity specifies a subset of processors on which a process may run, whereas soft affinity leaves the processor selection to the OS.

What represents layer zero (0) in the layered approach?

Hardware

Which security level is identified by gathering information through malicious phone calls?

Human

Which protection goal is achieved by detecting latent errors at the interfaces between components subsystems?

Improving reliability

In what way is an O.S like a government?

It creates an environment within which other programs can do useful work.

Which of the following is true of SSL?

It is commonly used for secure communication on the Internet.

What is a benefit of creating a separate raw partition for use as swap space?

It is optimized for speed of access.

Which of the following statements regarding the WAFL file system is incorrect?

It provides little replication.

What is the purpose of an inverted page table?

It reduces memory usage to store addresses.

Which advantage does short-term scheduling have compared with long-term scheduling?

It takes less time to select a process to execute next.

_______ operating systems are designed primarily to maximize resource utilization.

Mainframe.

_______ is a set of software frameworks that provide additional services to application developers.

Middleware

_______ allow operating system services to be loaded dynamically.

Modules.

Which of the following is a principle that can improve the efficiency of I/O?

Move processing primitives into hardware.

____ layer security generally has been standardized on IPSec.

Network

How is the array of logical blocks mapped onto the hard disk?

Onto the sectors of the disk sequentially

Which of the following statements is incorrect?

Operating Systems provide both command line as well as graphical user interfaces.

Which of the following statements is true?

Operations on atomic integers do not require locking

Which algorithm has the lowest possible page-fault rate and does not suffer from Belady's anomaly?

Optimal

What is the I/O bus standard that connects the processor-memory subsystem to the fast devices?

PCI

What is the process of context switching?

Performing a state save and a state restore

Which component ensures the integrity of memory in a paged environment?

Protection bits

____ is a symmetric stream cipher.

RC4

____ I/O accesses a block device as a simple array of blocks.

Raw

Which system call is used for device manipulation?

ReadConsole()

What is a non-self-modifying code that never changes during execution?

Reentrant

Which strategy for assigning kernel memory uses cache to refer to a set of one or more physically contiguous pages that serve for each unique kernel?

Slab allocation

Which scheduling algorithm was designed especially for time sharing systems?

Round-robin

______ is not one of the major categories of system calls.

Security

How do code editors and code compilers usually access files?

Sequential access

Which access type is used when speed is important in linked allocation files?

Sequential access

Which of the following statements concerning open source operating systems is true?

Source code is freely available.

What kernel data structure can be used for one technique of passing parameters to system calls?

Stack

The ________ provides a portion of the system call interface for UNIX and Linux.

Standard C library

______ provide(s) an interface to the services provided by an operating system.

System calls

What is a benefit of using virtual memory?

System libraries can be shared.

What is the common name used to refer to the operating system programs?

System programs

The ____ is the number of entries in the TLB multiplied by the page size.

TLB reach

Which of the following is true of a blocking system call?

The execution of the application is suspended when the call is issued.

Which of the following is a key property of an immutable file?

The file name may not be reused.

Which general-purpose storage is accessed directly by the CPU?

The main memory

Which collection of pages references the most recent set of delta parameters (Δ)?

The working set

Which of the following is considered a benefit when using the slab allocator?

There is no memory fragmentation

Which of the following statements is true with respect to hashed page tables?

They are a common approach for handling address spaces larger than 32 bits.

Which statement concerning privileged instructions is considered false?

They cannot be attempted from user mode.

Which of the following statements regarding solid state disks (SSDs) is false?

They generally consume more power than traditional hard disks.

_____ occurs when a process spends more time paging than executing.

Thrashing

What is the role of the OS?

To manage a computer's hardware

What is the rate at which data flows from the hard disk to the computer?

Transfer

What is the most common way of structuring directories?

Tree-Structured Directories

Which of the following statements is false? a. Swapping works in conjunction with virtual memory techniques. b. Some systems allow for multiple swap spaces (disks). c. Solaris only swaps pages of anonymous memory. d. Typically, entire processes are swapped into memory.

Typically, entire processes are swapped into memory.

What is an example of a policy?

User access

Which type of OS service uses the CLI?

User interface

What is the mode of the operating system when a user program is running?

User mode

Which solution resolves slow access time to user memory location when implementing paging?

Using the translation look-aside buffer (TLB)

What is the name of the memory allocation scheme where the operating system keeps a table of available holes?

Variable partition

Which of the following is true of the Java programming language in relation to protection?

When a class is loaded, the JVM assigns the class to a protection domain that gives the permissions of that class.

When does starvation occur in the priority scheduling algorithm?

When a process is waiting indefinitely

Which of the following operating systems is not open source?

Windows

_____ is the dynamic storage allocation algorithm that results in the largest leftover hole in memory.

Worst-fit

A code segment that misuses its environment is called ____.

a Trojan horse

Pthreads refers to ________.

a specification for thread behavior

Host-attached storage is ____.

accessed via local I/O ports

What is the correct order of operations for protecting a critical section using mutex locks?

acquire() followed by release()

A(n) ______ matches the process with each entry in the TLB.

address space identifier

A denial of service attack is ____.

aimed at disrupting legitimate use of a system

Signals can be emulated in Windows through _______.

asynchronous procedure calls

The OpenMP #pragma omp critical directive _______

behaves much like a mutex lock

Transfers between memory and disk are performed a ____.

block at a time

DMA controllers ____.

can steal memory access cycles from the main CPU

In the reacquisition scheme for implementing the revocation of capabilities, ____.

capabilities are periodically deleted from each domain

What are the two ways to multi-thread a processing core?

coarse-grained, fine-grained

Policy _______

determines what will be done.

A ____ is a public key digitally signed by a trusted party.

digital certificate

A(n) ______ is a custom build of the Linux operating system.

distribution

An instruction that executes atomically _______.

executes as single, uninterruptible unit.

_______ is a mobile operating system designed for the iPhone and iPad.

iOS

The most common technique for writing multithreaded Java programs is _______.

implementing the Runnable interface and defining its run() method.

Android runs Java programs ____________.

in the Dalvik virtual machine

The _________ process is assigned as the parent to orphan processes

init

Optimal page replacement ____.

is used mostly for comparison with other page replacement schemes

A(n) ________________ allows several unrelated processes to use the pipe for communication.

named pipe

Systems in which memory access times vary significantly are known as __________.

non-uniform memory access

A(n) ___________ is the unit of work in a system.

process

The two general approaches to load balancing are _________ and _________

push migration, pull migration

What is the term for describing the situation where shared data may be manipulated concurrently and the outcome of the execution depends upon the order of access?

race condition

Embedded computers typically run on a _______ operating system.

real-time

In MULTICS, the protection domains are organized in a _____.

ring structure

With segmentation, a logical address consists of _____.

segment number and offset

What is the name of the bit in a UNIX system that associates each file with an owner and domain?

setuid bit

Which of the following is not a reason explaining why mobile devices generally do not support swapping?

small size of mobile applications do not require use of swap space

Bluetooth and 802.11 devices use wireless technology to communicate over several feet, in essence creating a _______.

small-area network.

A(n) ____ file is a sequence of functions.

source

A(n) ____ is a buffer that holds output for a device that cannot accept interleaved data streams.

spool

The ______ of a process contains temporary data such as function parameters, return addresses, and local variables.

stack

A sense key reports on the failure of a SCSI device by ____.

stating the general nature of the failure

A _____ is a private network connecting servers and storage units.

storage area network

A mount point is _____.

the location within the file structure where the file system is to be attached

A _______ provides API for creating and managing threads.

thread library.

A _______ can be used to prevent a user program from never returning control to the operating system.

timer

The surface of a magnetic disk platter is divided into ____.

tracks

A character-stream device ____.

transfers data a byte at a time

Swap space management ____.

tries to provide the best throughput for the virtual memory system

A boot block _______.

typically only knows the location and length of the rest of the bootstrap program.

A __________ contains the same pages for memory-mapped IO as well as ordinary IO.

unified buffer cache

A process that has terminated, but whose parent has not yet called wait(), is known as a _________ process

zombie