cs433 final

Processes p and q execute the instructions x = x + 1 and x = x + 2, respectively. Initially x = 0. After execution of the interleaved code in the following order, x = Answer.

1

Given the logical address 0xAEF9 (in hexadecimal) with a page size of 256 bytes, what is the page number? Select one: A.0xAE B.0xF9 C.0xA D.0x00F9

A. 0xAE

A translation look-aside buffer is used to Select one: A.cache page table entries. B.store the address of the page table in memory. C.size of the logical address space of the currently running process. D.store page size.

A. cache page table entries.

Given the logical address 0xAEF9 (in hexadecimal) with a page size of 256 bytes, what is the page offset? Select one: A. 0xAE B. 0xF9 C. 0xA D. 0xEF9

B. 0xF9

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? Select one: A.199 B.201 C.200 D.300

C. 200

Assume a system uses 2-level paging and has a TLB hit ratio of 90%. It requires 15 nanoseconds to access the TLB, and 85 nanoseconds to access main memory. What is the effective memory access time in nanoseconds for this system? Select one: A. 22 B. 108.5 C. 30.5 D. 117

D. 117

An advantage of virtual memory is that Select one: A.a program can be much larger than the size of physical memory. B.the programmers can concentrate programming the problem instead of worrying about the amount of physical memory available. C.it provides a way to execute a program that is only partially loaded in memory. D.All of the above.

D. All of the above.

Which of the following data structures in the banker's algorithm is a vector of length m, where m is the number of resource types? Select one: A.Need B.Allocation C.Max D.Available

D. Available

Which of the following is true about the two versions of readers-writers problem? Select one: A.In the first readers-writers problem, a writer may starve if a continuous series of readers arrive before the earlier readers exit their critical section. B.In the second readers-writers problem, a reader may starve if a continuous series of readers arrive before the earlier readers exit their critical section. C.In the first readers-writers problem, a writer may starve if a continuous series of writers arrive before the earlier writers exit their critical section. D.In the second readers-writers problem, a writer may starve if a continuous series of readers arrive before the earlier readers exit their critical section.

A. In the first readers-writers problem, a writer may starve if a continuous series of readers arrive before the earlier readers exit their critical section.

Which of the following is NOT true? Select one: A. Since semaphore and mutex lock are tools for synchronization, process that have used semaphores or mutex locks should not cause deadlocks B. Semaphores and mutex locks may be shared resources that difference processes contend for, and hence deadlocks may occur C. a set of processes is in a deadlocked state when every process in the set is waiting for an event that can be caused only by another process in the set D. none of the above

A. Since semaphore and mutex lock are tools for synchronization, process that have used semaphores or mutex locks should not cause deadlocks

A thread using POSIX condition variables, a thread Select one: A. must lock the associated mutex lock before calling pthread_cond_wait and unlock it after calling pthread_cond_signal. B. must lock the associated mutex lock before calling pthread_cond_wait, but doesn't need to unlock it after calling pthread_cond_signal. C. doesn't need to lock the associated mutex lock before calling pthread_cond_wait, but must unlock it after calling pthread_cond_signal. D. doesn't need to lock the associated mutex lock before calling pthread_cond_wait and doesn't need to unlock it after calling pthread_cond_signal.

A. must lock the associated mutex lock before calling pthread_cond_wait and unlock it after calling pthread_cond_signal.

A page-table base register stores Select one: A.a pointer to the page table in memory. B.the starting logical address of the page currently being accessed. C.the starting physical address of the frame currently being addressed. D.the page size of the page currently being accessed.

A.a pointer to the page table in memory.

Which of the following indicates that Pi can enter the critical section in Peterson's solution? Select one: A.flag[j] == false or turn == i B.flag[j] == true or turn == i C.flag[j] == false or turn == j D.flag[j] == true and turn == j

A.flag[j] == false or turn == i

Which of the following critical-section problem's requirements ensures only one process is active in its critical section at a time? Select one: A.mutual exclusion B.progress C.bounded waiting D.none of the above

A.mutual exclusion

Assume the value of the base and limit registers of a process are 1200 and 350 respectively. Which of the following physical addresses is allocated to this process? Select one: A. 355 B. 1205 C. 1551 D. all of the above

B. 1205

A claim edge in a resource-allocation graph indicates that Select one: A.a process has been allocated a resource. B.a process may request a resource. C.a process may release a resource that it has already been assigned. D.a process has requested a resource.

B. a process may request a resource.

A free-frame list Select one: A.is a set of all frames that are filled with all zeros. B.is a set of all frames that are currently unallocated to any process. C.is a set of all frames that are currently being shared by at least two processes. D.is a set of all frames that are used for stack and heap memory.

B. is a set of all frames that are currently unallocated to any process.

In a single processor system running Windows, when the kernel accesses a global resource, it Select one: A. uses spinlocks. B. masks all interrupts. C. uses a dispatcher object. D. uses atomic integers.

B. masks all interrupts.

Reentrant code is easier to share when paging is used, because Select one: A.each process can modify that code its own way. B.the code doesn't change during execution. C.the code changes are identical for each process. D.All of the above.

B. the code doesn't change during execution.

Deadlocks can be prevented only if Select one: A.all four necessary conditions cannot hold. B.at least one of the four necessary conditions cannot hold. C.mutual exclusion condition cannot hold. D.circular wait condition cannot hold.

B.at least one of the four necessary conditions cannot hold.

_____ is the method of binding instructions and data to memory performed by most general-purpose operating systems. Select one: A.Interrupt binding B.Compile time binding C.Execution time binding D.Load-time binding

C. Execution time binding

Suppose that there are two resource types (R1 and R2) with five resources each available to four processes. At time 0, the following data is collected. The table indicates the process, the number of resources of each type currently allocated to the processes, and the current request of each resource type by each process.Process Allocation Request R1 R2 R1 R2 P0 2 0 3 2 P1 1 1 1 0 P2 0 1 1 1 P3 1 1 3 2Which of the following sentences is correct? Select one: A. All four processes are currently deadlocked. B. The system is not deadlocked. C. Processes P0 and P3 are deadlocked. D. Processes P0, P1 and P3 are deadlocked.

C. Processes P0 and P3 are deadlocked.

In a system that uses deadlock detection algorithm, Select one: A.a deadlock is detected as soon as it occurs. B.a deadlock is detected just before it occurs. C.a deadlock is detected sometime after it has occurred but not necessarily immediately. D.a deadlock is detected sometime before it occurs, but not necessarily just before.

C. a deadlock is detected sometime after it has occurred but not necessarily immediately.

In a system resource-allocation graph, ____. Select one: A.a directed edge from a process to a resource is called an assignment edge B.a directed edge from a resource to a process is called a request edge C.a directed edge from a process to a resource is called a request edge D.None of the above

C. a directed edge from a process to a resource is called a request edge

In demand paging, Select one: A.a page loaded in memory may never be accessed. B.all pages that a program will access during execution are loaded in memory in the beginning. C.a page is loaded in memory only when it is needed during execution. D.a page is loaded in memory just before it is needed.

C. a page is loaded in memory only when it is needed during execution.

Address translation from a logical address to a physical address in IA-32 architecture is comprised of Select one: A. a segmentation unit that translates the logical address to its physical address. B. a paging unit that translates the logical address to its physical address. C. a segmentation unit followed by a paging unit that translate the logical address to its physical address. D. a paging unit followed by a segmentation unit that translates the logical address to its physical address.

C. a segmentation unit followed by a paging unit that translate the logical address to its physical address.

In the monitor solution for dining-philosophers problem (Figure 7.7), a philosopher may start eating Select one: A.at the end of the pickup function before exiting the function. B.in the beginning of the putdown function C.after exiting the pickup function and before entering the putdown function. D.All of the above.

C. after exiting the pickup function and before entering the putdown function.

Which of the following is true for race condition? Select one: A. race condition occurs where several processes access and manipulate the same data concurrently B. when race condition occurs, the outcome of the execution depends on the particular order in which the access takes place C. both of the above D. none of the above

C. both of the above

Which of the following variables are shared between the processes in Peterson's solution? Select one: A. int turn B. boolean flag[2] C. both of the above D. none of the above

C. both of the above

One necessary condition for deadlock is ______, which states that there is a chain of waiting processes whereby P0 is waiting for a resource held by P1, P1 is waiting for a resource held by P2, and Pn is waiting for a resource held by P0. Select one: A.hold and wait B.mutual exclusion C.circular wait D.no preemption

C. circular wait

Suppose the size of a process is 10,000 bytes and the relocation register is loaded with value 5000, which of the following memory address this process can access? Select one: A.logical address 10,350 B.physical address 4,500 C.physical address 10,350 D.None of the above

C. physical address 10,350

The counting semaphore is initialized to ___________. Select one: A. 0 B. 1 C. the number of resources available D. none of the above

C. the number of resources available

What is the correct order of operations for protecting a critical section using a binary semaphore? Select one: A. release() followed by acquire() B. acquire() followed by release() C. wait() followed by signal() D. signal() followed by wait()

C. wait() followed by signal()

Which of the following critical-section problem's requirements limits the amount of time a program will wait before it can enter its critical section? Select one: A.mutual exclusion B.progress C.bounded waiting D.none of the above

C.bounded waiting

Which of the following is not true about compare_and_swap instruction? Select one: A. It is a hardware instruction B. It is executed atomically C. It returns the original value of passed parameter D. It sets the new value of passed parameter to "TRUE" E. It sets the variable "value" the value of the passed parameter "new_value" but only if "value" =="expected"

D. It sets the new value of passed parameter to "TRUE"

Which of the following is not true about test_and_set instruction? Select one: A. It is a hardware instruction B. It is executed atomically C. Returns the original value of passed parameter D. Returns the new value of passed parameter E. Set the new value of passed parameter to "TRUE"

D. Returns the new value of passed parameter

Suppose that there are ten resources available to three processes. At time 0, the following data is collected. The table indicates the process, the maximum number of resources needed by the process, and the number of resources currently owned by each process.Process Maximum Needs Currently Owned P0 10 4P1 3 1P2 5 4At time 1, P1 requests a resource. Which of the following is correct? Select one: A.The request will be granted, since the current state is safe. B.The request will not be granted, since the current state is not safe. C.The request will be granted, since the state after granting the request will be safe. D.The request will not be granted, since the state after granting the request will be unsafe.

D. The request will not be granted, since the state after granting the request will be unsafe.

The dirty (modify) bit identifies Select one: A.a page that has been corrupted. B.a page that needs to be reloaded when accessed. C.a page that is shared by multiple processes. D.a page that has been modified since it was loaded.

D. a page that has been modified since it was loaded.

In a resource allocation graph, when a process releases a resource, Select one: A.a request edge is inserted. B.an assignment edge is inserted. C.a request edge is removed. D.an assignment edge is removed.

D. an assignment edge is removed.

In the solution provided for readers-writers problem in Section 7.1.2, if a writer is in the critical section, and multiple readers and writers are waiting, Select one: A. all waiting readers will be allowed to enter the critical section when the writer in the critical section exits. B. all waiting writers will be allowed to enter the critical section when the writer in the critical section exits. C. exactly one of the waiting writers will be allowed to enter the critical section when the writer in the critical section exits. D. either all waiting readers or exactly one writer will be allowed to enter the critical section when the writer in the critical section exits.

D. either all waiting readers or exactly one writer will be allowed to enter the critical section when the writer in the critical section exits.

One necessary condition for deadlock is ______, which states that a resource can be released only voluntarily by the process holding the resource. Select one: A.hold and wait B.mutual exclusion C.circular wait D.no preemption

D. no preemption

Assume count is a variable name, which of the following operations is atomic? Select one: A. count++ B. count-- C. both of the above D. none of the above

D. none of the above

External fragmentation is Select one: A.when there is some unused memory that cannot be allocated to a process. B.when the amount of available memory is less than the size of a process. C.when a process is broken up into smaller parts for memory allocation. D.when there is enough total memory space to satisfy a request but the available spaces are not contiguous.

D. when there is enough total memory space to satisfy a request but the available spaces are not contiguous.

A reader-writer lock is useful when Select one: A.there are a significantly large number of processes attempting to enter a critical section. B.there are a significantly large number of consumer processes attempting to read data from a bounded buffer. C.there are a significantly small number of reader processes attempting to read in the critical section. D.there are a significantly large number of reader processes attempting to read in the critical section.

D.there are a significantly large number of reader processes attempting to read in the critical section.

A call to pthread_cond_signal() (used by POSIX threads, called Pthread) releases the associated mutex lock. Select one: True False

False

A mutex lock is released immediately after entering a critical section. Select one: True False

False

Fragmentation does not occur in a paging system. Select one: True False

False

If the sum of all needs for a resource type exceeds the available number of instances of that resource type, the system state is unsafe. Select one: True False

False

In general, virtual memory decreases the degree of multiprogramming in a system. Select one: True False

False

Inverted page tables require each process to have its own page table. Select one: True False

False

Mobile operating systems typically support swapping. Select one: True False

False

Monitors are a theoretical concept and are not practiced in modern programming languages Select one: True False

False

Mutex locks and counting semaphores are essentially the same thing. Select one: True False

False

The value of a counting semaphore can range only between 0 and 1. Select one: True False

False

There is a 1:1 correspondence between the number of entries in the TLB and the number of entries in the page table. Select one: True False

False

When the mutex lock is implemented based on a binary semaphore, it should be initialized to be 0. Select one: True False

False

Which of the following is NOT true regarding semaphore implementation? Select one: A. It suffers from the busy waiting problem B. Semaphore has a waiting queue associated with the semaphore C. When a process executes the wait() operation and finds that the semaphore value is not positive, it will suspend itself D. A process that is suspended, waiting on the semaphore, should be restarted when some other process executes a signal() operation.

It suffers from the busy waiting problem

A page fault must be preceded by a TLB miss. Select one: True False

True

Dining philosophers problem is important because it represents a class of problems where multiple processes need to share multiple resources. Select one: True False

True

Dispatcher objects in Windows are used for synchronization outside the kernel. Select one: True False

True

Hashed page tables are particularly useful for processes with sparse address spaces. Select one: True False

True

If no process is suspended, then the signal() operation of a condition variable has no effect. Select one: True False

True

In swapping with paging technique, individual pages of a process are swapped in or out. Select one: True False

True

Instructions from different processes can be interleaved when interrupts are allowed.

True

Race conditions can result in corrupted values of shared data.

True

Semaphores and mutex locks both provide mutual exclusion. Select one: True False

True

Spinlocks are not appropriate for single-processor systems. Select one: True False

True

The ARMv8 architecture uses up to four-level paging. Select one: True False

True

The banker's algorithm is useful in a system with multiple instances of each resource type. Select one: True False

True

The instruction that causes a page fault needs to be re-executed after the fault has been handled. Select one: True False

True

The wait-for graph scheme is not applicable to a resource allocation system with multiple instances of each resource type. Select one: True False

True

Without a mechanism such as an address-space identifier, the TLB must be flushed during a context switch. Select one: True False

True

test_and_set() is an atomic machine instruction that is used to solve the synchronization problem. Select one: True False

True

If memory access time is 100 nanoseconds and average page fault service time 5 milliseconds, the probability of page faults must be less ______ to keep the performance degradation less than 20%. Select one: a. 0.000004 b. 0.000005 c. 0.00001 d. 0.0000025

a. 0.000004

Assume a system has a TLB hit ratio of 90%. It requires 1 nanosecond to access the TLB, and 20 nanoseconds to access the main memory. What is the effective memory access time (EAT) in nanoseconds for this system? Select one: a. 23 b. 21 c. 41 d. 39

a. 23

In the solution to the bounded-buffer problem in 7.1.1, what may happen if the order of wait(empty) and wait(mutex) statements are swapped in the producer process? Select one: a. It may result in a deadlock. b. It is OK to swap the order of wait() statements. c. More than one producer may access the buffer at the same time. d. More than one consumer may access the buffer at the same time.

a. It may result in a deadlock.

Given the logical address 0xF4BCAEF9 (in hexadecimal) with a page size of 4KB (2^12), what are the page number and offset respectively? Select one: a. Page number = 0xF4BCA, page offset = 0xEF9 b. Page number = 0xF4BC, page offset = 0xAEF9 c. Page number = 0xF4B, page offset = 0xBCAEF9 d. Page number = 0xF4BCAE, page offset = 0xF9 e. none of the above.

a. Page number = 0xF4BCA, page offset = 0xEF9

In the structure of the producer process shown in Figure 7.1, what would be a possible outcome if wait(empty) is replaced with signal(empty) and signal(full) is replaced with wait(full) in the producer process? Select one: a. Producer will remain blocked after adding an item in the buffer. b. Consumer will remain blocked after taking out an item from the buffer. c. Producer and consumer may access the buffer at the same time. d. Producer will never be able to access the buffer.

a. Producer will remain blocked after adding an item in the buffer.

The two atomic operations of a mutex lock are Select one: a. acquire() and release() b. compare() and swap() c. test() and set() d. wait() and signal()

a. acquire() and release()

A(n) _______ refers to where a process is accessing/updating shared data. Select one: a. critical section b. entry section c. mutex d. race condition

a. critical section

A(n) ____ page table has one page entry for each real page (or frame) of memory. Select one: a. inverted b. hierarchical c. clustered d. virtual

a. inverted

The mapping of a logical address to a physical address is done in hardware by the ________. Select one: a. memory-management-unit (MMU) b. memory address register c. relocation register d. dynamic loading register

a. memory-management-unit (MMU)

How many philosophers at most may eat simultaneously in the Dining Philosophers problem with 5 philosophers? Select one: a. 1 b. 2 c. 3 d. 4

b. 2

What is the correct order of operations for protecting a critical section using mutex locks? Select one: a. release() followed by acquire() b. acquire() followed by release() c. wait() followed by signal() d. signal() followed by wait()

b. acquire() followed by release()

Consider a logical address space of 2,048 pages with a 4-KB page size, how many bits are required in the logical address? Select one: a. 12 b. 11 c. 23 d. 32

c. 23

Considering a 32-bit logical memory space and page size of 8KB (2^13), what is the total number of pages in logical memory? Select one: a. 32 because the logical memory is 32-bit. b. 8192 because the page size if 2^13 bytes. c. 2^19 because page number is 19-bit. d. 20 because page number is 20-bit. e. None of the above.

c. 2^19 because page number is 19-bit.

Given the following segment table: Segment Limit Base 0 1000 1400 1 400 6300 2 400 4300 3 1100 3200 4 1000 4700 What are the physical addresses for segmentation logical address (1, 43) and (2, 567) respectively? Select one: a. 6343 and 4867 b. 443 and 967 c. 6343 and Error d. 1043 and 2567 e. None of the above

c. 6343 and Error

_____ is not a technique used for handling critical sections in operating system kernels. Select one: a. Nonpreemptive kernels b. Disabling interrupts c. Peterson's algorithm d. Spin locks

c. Peterson's algorithm

Suppose a system with four resource types {R0, R1, R2, R3} of total counts {8, 5, 9, 7} and five processes. The maximum claims of the process are shown in the following table Process R0 R1 R2 R3 P0 3 2 1 4 P1 0 2 5 2 P2 5 1 0 5 P3 1 5 3 0 P4 3 0 3 3 Figure 1. Maximum claim table The current allocation of resources is as following Process R0 R1 R2 R3 P0 2 0 1 1 P1 0 1 2 1 P2 4 0 0 3 P3 0 2 1 0 P4 1 0 3 0 Figure 2. Current resource allocation table Which of the following statement regarding the state of system is correct? Select one: a. The system is in a deadlock state because max claim is more than the total number of resources. b. The system is in an unsafe state because there is no safe sequence of processes to complete. c. The system is in a safe state and <P2, P0, P4, P1, P3> is a safe sequence for processes to complete. d. The system is in a safe state and <P2, P3, P4, P0, P1> is a safe sequence for processes to complete. e. None of the above.

c. The system is in a safe state and <P2, P0, P4, P1, P3> is a safe sequence for processes to complete.

_____ is the dynamic contiguous memory allocation algorithm which results in the largest leftover hole in memory. Select one: a. First fit b. Best fit c. Worst fit d. Random fit

c. Worst fit

A call to pthread_cond_signal() Select one: a. releases the mutex lock and signals one thread waiting on the condition variable. b. releases the mutex lock and signals all threads waiting on the condition variable. c. signals one thread waiting on the condition variable, but does not release the mutex lock. d. signals all threads waiting on the condition variable, but does not release the mutex lock.

c. signals one thread waiting on the condition variable, but does not release the mutex lock.

A system can recover from a deadlock by Select one: a. aborting one process at a time until the deadlock cycle is eliminated. b. aborting all deadlocked processes. c. preempting some resources from one or more of the deadlocked threads. d. All of the above.

d. All of the above.

If we give up hold-and-wait condition to prevent deadlock, Select one: a. resource utilization may below. b. starvation is possible. c. whenever a thread requests a resource, it does not hold any other resources. d. All of the above.

d. All of the above.

To recover from a deadlock using resource preemption, Select one: a. the order of resources and processes that need to be preempted must be determined to minimize cost. b. if a resource is preempted from a process, the process must be rolled back to some safe state and restarted from that state. c. ensure that starvation does not occur from always preempting resources from the same process. d. All of the above.

d. All of the above.

Which of the following statements is true? Select one: a. A safe state is a deadlocked state. b. A safe state may lead to a deadlocked state. c. An unsafe state is necessarily, and by definition, always a deadlocked state. d. An unsafe state may lead to a deadlocked state.

d. An unsafe state may lead to a deadlocked state.

Which of the following is NOT true regarding a condition variable, e.g. x? Select one: a. A condition variable allows processes to be suspended and wait in the critical section. b. x.wait() means that the process invoking this operation is suspended until another process invokes x.signal() c. The x.signal() operation resumes exactly one suspended process if there are any. d. If no process is suspended, then the x.signal() operation still affects the state of x by incrementing its internal value.

d. If no process is suspended, then the x.signal() operation still affects the state of x by incrementing its internal value.

What is the purpose of the mutex semaphore in the implementation of the bounded-buffer problem using semaphores? Select one: a. It indicates the number of empty slots in the buffer. b. It indicates the number of occupied slots in the buffer. c. It controls access to the shared buffer. d. It ensures mutual exclusion.

d. It ensures mutual exclusion.

If a shared global variable x is initialized to 1, two threads execute concurrently statements "x++" and "x--" respectively. What are the possible values of x after the execution of the statements? Select one: a. 0 b. 1 c. 2 d. all of the above.

d. all of the above.

A ___ type presents a set of programmer-defined operations that are provided mutual exclusion within it. Select one: a. transaction b. signal c. binary d. monitor

d. monitor

The two atomic operations of a semaphore are Select one: a. acquire() and release() b. test() and set() c. compare() and swap() d. wait() and signal()

d. wait() and signal()