MIT201 QUIZES

MIT201

Unit 1

Quiz 1

1. Jobs may have to be swapped in and out of main memory to the ____________ memory.

Declarative

long-term

External

Secondary

Feedback:Right choice.Time-sharing operating systems are more complex than multi-programmed operating systems. This is because in multi-programming several jobs must be kept simultaneously in memory, which requires some form of memory management and protection.

Score 0 of 1 2. Job scheduling brings the ability of ____________________.

Single-programming

Multi-programming

Multithreading

Multitasking

Feedback:Not the right choice. Multitasking is a method where multiple tasks, also known as processes, are performed during the same period of time. The tasks share common processing resources, such as a CPU and main memory. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for that task.

Score 0 of 1

3. The concept of spooling introduced an important data structure called the _____________.

Group jobs

Feedback:Not the right choice. Spooling creates a number of jobs on the disk which are ready to be executed / processed. The operating system now has to choose from the job pool a job that is to be executed next.

Job groups

Spool jobs

Job pool

Score 1 of 1 4. Even though the processing speed increased to a large extent because of batch processing, the ___ was often idle.

Hard disk drive

Memory

CPU

Feedback:Right choice. This is because of the disparity between operating speeds of electronic devices like the CPU and the mechanical I/O devices. CPU operates in the microsecond / nanosecond ranges whereas I/O devices work in the second / minute range.

Monitor

Score 1 of 1 5. A/an ________________ system is a system software (set of system programs) which provides an environment to help the user execute programs.

Operating

Feedback:"Right choice. The operating system is a resource manager which allocates and manages various resources like processor(s), main memory, input/output devices and information on secondary storage devices.

Distributed

Real-time

Resouce-sharing

Score 1 of 1 6. It is a software that acts as an interface between the hardware of the computer and the application software that users need to run on the computer.

Programming

Application

System

Feedback:Right choice. This software provides a general programming environment in which programmers can create specific applications to suit their needs. This environment provides new functions that are not available at the hardware level and performs tasks related to executing the application program.

Embedded

Score 1 of 1 7. Which software consists of the programs for performing tasks particular to the machine's utilization?

System

Application

Feedback:Right choice.Examples of application software include spreadsheets, database systems, desktop publishing systems, program development software and games. Application software is generally what we think of when someone speaks of computer programs. This software is designed to solve a particular problem for users.

Embedded

Programming

Quiz 2Hi

1. Name the two flavors of real-time systems.

Hard real-time, soft real-time

Feedback:Right choice. A hard real-time system guarantees that critical tasks complete at a specified time. A less restrictive type of real-time system is soft real-time system, where a critical real-time task gets priority over other tasks, and remains that priority until it is completed.

Complicated real-time, simple real-time

Positive real-time, negative real-time

Internal real-time, external real-time

Score 0 of 2 2. In tightly coupled systems, the processors share the _________ or a __________.

Power, electricity

Memory, clock

Memory, space

Feedback:Not the right choice. Multi-processor systems have many processors, and all these processors share the computer bus, the clock and sometimes memory and peripheral devices.

Clock, power

Score 2 of 2 3. When power is turned ________ BIOS takes control. It does___________ self test.

Off, energy

On, electric

Off, power-off

On, power-on

Feedback:Right choice. The test sees whether memory is OK and all other relevant units function. Having done this, it reads from the disk a small portion of OS known as the boot and loads it into the main memory. This boot program then “pulls” the rest of the OS from the disk and stores it in the main memory. This is known as “booting the system”.

Score 0 of 2 4. The operating system of PCs consists of two parts, namely:

BIOS, DOS

Internal, external

Feedback:Not the right choice. The operating system of PCs consists of two parts. One part is called the BIOS (Basic Input Output System) which is stored in a ROM (Read Only Memory). The other part, called the DOS (Disk Operating System), is stored in a floppy disk or a hard disk.

Electrical, digital

Mechanical, electrical

Quiz 3Hihi

1. "Identify the following statements as True or False: 1. A kernel only supports the notion of process and does not include the concept of a procedure.2. A kernel only supports the notion of procedure and does not include the concept of a process.3. A kernel only supports the notion of process and does not include the concept of a device.4. A kernel only supports the notion of process and does not include the concept of a resource."

Only statement 2 is true.


Statements 1 and 4 are true.

Feedback: A kernel is a fundamental set of primitives that allows the dynamic creation and control of processes, as well as communication among them.


Score 0 of 4 2. "Identify the following statements as True or False:1.Dijkstra suggested the layered approach to increase the design and implementation complexities of an operating system.2. Dijkstra suggested the layered approach to lessen the design and implementation complexities of a device.3. Dijkstra suggested the layered approach to lessen the process of an operating system.4. Dijkstra suggested the layered approach to lessen the design and implementation complexities of an operating system."



Feedback: The layered approach has all the advantages of a modular design. In the modular design, the system is divided into several modules, and each module is designed independently. Likewise in layered approach each layer can be designed, coded and tested independently. Consequently the layered approach considerably simplifies the design, specification and implementation of an operating system.



Score 0 of 4 3. Match the points of Part A with Part B:

Match Correct Answer User answer Feedback

Simple Batch Operating Systems

The operating system was very simple and its major task was to transfer control from one job to another. The operating system was resident in memory .

The operating system was very simple and its major task was to transfer control from one job to another. The operating system was resident in memory .

Multi-programmed Batched Operating Systems

It increases CPU utilization by organizing jobs in such a manner that CPU always has a job to execute.

It is a logical extension of multi-programming. It provides interactive use of the system.

Time-sharing Operating Systems

It is a logical extension of multi-programming. It provides interactive use of the system.

It increases CPU utilization by organizing jobs in such a manner that CPU always has a job to execute.

Personal Computer Operating Systems

The Os for PCs were designed as a single user single task operating system, that is, it is assumed that only one user uses the machine and runs only one program at a time.

The Os for PCs were designed as a single user single task operating system, that is, it is assumed that only one user uses the machine and runs only one program at a time.

Quiz4Hi

1. A _________________ environment is another kind of a virtual machine.

Real-time

Virtual

Feedback:Right choice. In fact, it is a virtualized environment for running user-level programs (i.e. not the operating system kernel and drivers, but applications). Virtual environments are created using the software implementing operating system-level virtualization approach, such as Virtuoso, FreeBSD Jails, Linux-VServer, Solaris Containers, Cheroot jail and OpenVZ.

Distributed computing

Java runtime

Score 0 of 1 2. Another meaning of virtual machine is a piece of __________________________ that isolates the application being used by the user from the computer.

Computer resource

Feedback: A resource, or system resource, is any physical or virtual component of limited availability within a computer system. Every device connected to a computer system is a resource. Every internal system component is a resource."

Computer devices

Computer hardware

Computer software

Score 0 of 1 3. The best current methodology for operating-system design involves using object-oriented programming techniques to create a _____________.

Modular hard disk

Modular windows

Feedback:. Here, the kernel has a set of core components and dynamically links in additional services either during boot time or during run time. Such a strategy uses dynamically loadable modules and is common in modern implementations of UNIX, such as Solaris, Linux and MacOS.

Modular kernel

Secular kernel

Score 1 of 1 4. One benefit of the micro-kernel approach is the ease of __________________ the operating system.

Extending

Feedback:"Right choice. All new services are added to the user space and consequently do not require modification of the kernel. When the kernel needs to be modified, the changes tend to be fewer, because the microk-ernel is a smaller kernel. The resulting operating system is easier to port from one hardware design to another.

Restricting

Modifying

Changing

Score 1 of 1 5. The final problem with layered implementations is that they tend to be __________ efficient than other types.

Not

More

Less

Feedback:Right choice. When a user program executes an I/O operation, it executes a system call that is trapped to the I/O layer, which calls the memory-management layer and then in turn calls the CPU-scheduling layer and, at last, is passed to the hardware. At each layer, the parameters may be modified; data may need to be passed, and so on. Each layer adds overhead to the system call; the net result is a system

call that takes longer than does one on a non-layered system.

Most

Score 1 of 1 6. The major difficulty with the _______________ approach involves appropriately defining the various layers.

Top-middle

Layered

Feedback:Right choice. Because a layer can use only lower-level layers, careful planning is necessary. For example, the device driver for the backing store (disk space used by virtual-memory algorithms) must be at a lower level than the memory-management routines, because memory management requires the ability to use the backing store.

Vertical

Horizontal

UNIT 2

QUIZ1

1. How many types of of loadable kernel modules are in solaris operating system?

Six

Feedback:" Choice.the Solaris operating system structure is organized around a core kernel with seven types of loadable kernel modules:

1. Scheduling classes2. File systems3. Loadable system calls4. Executable formats5. STREAMS formats6. Miscellaneous7. Device and bus drivers

Seven

Eight

Nine

Score 0 of 4 2. "Identify which of the following statement is True or False 1. The operating system-level architecture has high overhead that helps maximize efficient use of server resources.2. The operating system-level architecture has low overhead that helps maximize efficient use of server resources.3. The operating system-level architecture has low overhead that helps minimize efficient use of server resources.4. The operating system-level architecture has high overhead that helps minimize efficient use of server resources."


Statement 2 is true.



Feedback: The virtualization introduces only a negligible overhead and allows running hundreds of virtual private servers on a single physical server.In contrast, approaches such as virtualization (like VMware) and para-virtualization (like Xen or UML) cannot achieve such level of density, due to overhead of running multiple kernels. From the other side, operating system-level virtualization does not allow running different operating systems (i.e. different kernels), although different libraries, distributions etc. are possible.

Score 4 of 4 3. "Which of the following statement is correct about virtualization?1. Software virtualization can be done in three major ways:• Emulation, full system simulation, or ""full virtualization with dynamic recompilation"".Para-virtualization• Native virtualization and ""full virtualization""2. Software virtualization can be done in three major ways:• Non-emulation, without simulation, or ""full virtualization with dynamic recompilation"".• Para-virtualization• Native virtualization and ""full virtualization"".3. Hardware virtualization can be done in three major ways:• Emulation, full system simulation, or ""full virtualization with dynamic recompilation"".• Para-virtualization• Native virtualization and ""full virtualization"".4. Software virtualization can be done in three major ways:• Emulation, full system simulation, or ""full virtualization with dynamic recompilation"".• virtualization• Native virtualization and ""full virtualization"".

Only statement 2

Only 1 and 3

Only 2 and 3

Only 1

Feedback:"Right choice. Software virtualization can be done in three major ways:• Emulation, full system simulation, or ""full virtualization with dynamic recompilation""– The virtual machine simulates the complete hardware, allowing an unmodified OS for a completely different CPU to be run.• Para-virtualization – The virtual machine does not simulate hardware but instead offers a special API that requires OS modifications. An example of this is XenSource's XenEnterprise (www.xensource.com)• Native virtualization and ""full virtualization""– the virtual machine only partially simulates enough hardware to allow an unmodified OS to be run in isolation, but the guest OS must be designed for the same type of CPU. The term native virtualization is also sometimes used to designate that hardware assistance through Virtualization Technology is used. "

QUIZ 2

1. Virtual machines can also perform the role of an emulator, allowing which of the following to be run?

Software applications, operating systems

Hardware, mainframe

Hardware, database systems

Software applications, database systems

Feedback: A virtual environment (otherwise referred to as virtual private server) is another kind of virtual machine. It is a virtualized environment for running user-level programs. Virtual environments are created using the software implementing operating system-level virtualization approach.

Score 0 of 2 2. In the layered approach, the ________________ is broken up into a number of _____________. The bottom layer is the hardware; the highest is the user interface.

Memory space, layers

Feedback: An operating system layer is an implementation of an abstract object made up of data and the operations that can manipulate those data. A typical operating system layer, say, layer M, consists of data structures and a set of routines that can be invoked by higher-level layers. Layer M, in turn, can invoke operations on lower-level layers.

Operating system, layers

Hardware, devices

Procedure, tasks

Score 2 of 2

3. The main function of the micro-kernel is to provide a communication facility between which of the following?

Client, services

Feedback:Right choice. There is little consensus regarding which services should remain in the kernel and which should be implemented in user space. Typically, however, micro-kernels provide minimal process and memory management, in addition to a communication facility.

Hardware, interfaces

Device, services

Client, interfaces

Score 0 of 2 4. Two common software packages that permit a heterogeneous collection of networked UNIX and/or Windows computers to be used as a single, large, parallel computer:

Word processors, spreadsheets

UNIX, Linux

Feedback: Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. Unix is a multitasking, multi-user computer operating system.

Graphic presentations, databases

PVM, MPI

UNIT3

QUIZ 1

1. "Identify the following statements as True or False: 1. The processes executing in the operating system may be either dependent processes or co-operating processes.2. The processes executing in the operating system may be either implicit processes or explicit processes.3. The processes executing in the operating system may be either real-time processes or para real-time processes.4. The processes executing in the operating system may be either independent processes or co-operating processes."





Feedback:Right choice. A process is said to be independent if it cannot affect or be affected by the other processes executing in the system. Any process that does not share data with any other process is independent. On the other hand, a process is co-operating if it can affect or be affected by the other processes executing in the system. Clearly any process that shares data with other processes is a co-operating process.

Score 4 of 4 2. "Identify the following statemetns as True or False:1.The main objective of multiprogramming is to see that no process is running so as to maximize CPU utilization.2. The main objective of multiprogramming is to see that all processes are always running so as to maximize CPU utilization.3. The main objective of multiprogramming is to see that some process is always running so as to minimize CPU utilization.4. The main objective of multiprogramming is to see that some process is always running so as to maximize CPU utilization."





Feedback:Right choice. The main objective of multiprogramming is to see that some process is always running so as to maximize CPU utilization, whereas in the case of time sharing, the CPU is to be switched between processes frequently, so that users interact with the system while their programs are executing.

Score 0 of 4 3. Match the points of part A with part B:


New Process being created. Process being created.

Running Instructions being executed. Process waiting for CPU.

Waiting Process waiting for an event to occur.

Process waiting for an event to occur.

Ready Process waiting for CPU. Instructions being executed.

QUIZ 2HI

1. Threads are very inexpensive to ________________________, and they are inexpensive to ______________________.

Create and destroy, represent

Feedback:Right choice. Threads require space to store, the PC, the SP, and the general-purpose registers, but they do not require space to share memory information, information about open files of I/O devices in use, etc. With so little context, it is much faster to switch between threads. In other

words, it is relatively easier for a context switch using threads.

Open and close, represent

Start and stop, destroy

Begin and finish, destroy

Score 2 of 2 2. Two major disadvantages of threads over multi-processes include:

Sharing, unsecured

Blocking, security

Feedback:"Right choice. Here are some of the disadvantages of threads over multiprocesses:• Blocking: The major disadvantage is that if the kernel is single threaded, a system call of one thread will block the whole process and CPU may be idle during the blocking period.• Security: Since there is an extensive sharing among threads, there is a potential problem of security. It is quite possible that one thread overwrites the stack of another thread (or damaged shared data) although it is very unlikely since threads are meant to cooperate on a single task."

Moving, closing

Unblocking, unsecured

Score 2 of 2 3. Which of the following ensures that some process is always running so as to maximize CPU utilization, whereas other switches the CPU between processes frequently?

Multiprogramming, scheduling

Multitasking, scheduling

Multiprogramming, time sharing

Feedback:"Right choice. In a uniprocessor system, there is always a single process running while the other processes need to wait till they get the CPU for execution on being scheduled.As a process enters the system, it joins a job queue that is a list of all processes in the system. Some of these processes are in the ready state and are waiting for the CPU for execution. These processes are present in a ready queue. The ready queue is nothing but a list of PCB’s

implemented as a linked list with each PCB pointing to the next. There are also some processes that are waiting for some I/O operation like reading from a file on the disk or writing onto a printer. Such processes are present in device queues. Each device has its own queue."

Multitasking, time sharing

Score 2 of 2 4. Name the schedulers that differ in the frequency of their execution.

Long-term, short-term

Feedback:Right choice. A short-term scheduler has to select a new process for CPU execution quite often as processes execute for short intervals before waiting for I/O requests. Hence, the short-term scheduler must be very fast or else, the CPU will be doing only scheduling work. A long-term scheduler executes less frequently since new processes are not created at the same pace at which processes need to be executed.

Positive, negative

Long, short

Implicit, explicit

Score 2 of 2 5. There are two main types of threads, namely:

Destruction, simplifying

Construction, deallocating

Destruction, debugging

User-Level Threads (ULTs), Kernel-Level Threads (KLTs)

Feedback:Right choice. User-level threads implement in user-level libraries, rather than via systems calls. So thread switching does not need to call operating system and to interrupt the kernel. Kernel Threads (Threads in Windows) are threads supplied by the kernel. All thread management is done by kernel. No thread library exists. The kernel knows about and manages the threads.

UNIT 4

QUIZ 1

1. What are the states of priority when CPU burst is large and small respectively?

Low, high

High, medium

High, low

Feedback: Priority is the inverse of the next CPU burst time. Larger the next CPU burst, lower is the priority and vice versa.

Internal, external

Score 0 of 2 2. Each queue has _______________ priority over ______ priority queues.

High, less important

Absolute, low

Absolute, high

High, absolute

Feedback:Queues themselves have priorities. Each queue has absolute priority over low priority queues. A process in a queue with lower priority will not be executed until all processes in a queue with higher priority have finished executing. If a process in a lower priority queue is executing (higher priority queues are empty) and a process joins a higher priority queue, the executing process is preempted to make way for a process in the higher priority queue.

Score 0 of 2 3. Which could be considered to move processes from lower priority queues to higher priority to avoid starvation?

Storing

Transfering

Feedback: Aging is a concept where the priority of a process waiting in the ready queue is increased gradually. Eventually the lowest priority process ages to attain the highest priority, by which it gets a chance to execute on the CPU. A solution to starvation is aging.

Debugging

Aging

Score 0 of 2 4. In priority scheduling, priorities can be defined in two ways. What are these?

Internally, externally

Positively, negatively

Long, short

Low, high

Feedback: In priority scheduling, priorities can be defined either internally or externally. The Internal definition of priority is based on some measurable factors, such as memory requirements, number of open files, and so on. External priorities are defined by criteria, such as the importance of the user depending on the user’s department and other influencing factors.

QUIZ 2

1. If processes with smaller CPU burst times arrive earlier, their average waiting and average turnaround times are lesser. The algorithm also suffers from what is known as:

Pushing effect

Feedback:" Let there be a mix of one CPU bound process and many I/O bound processes in the ready queue. The CPU bound process gets the CPU and executes (long I/O burst). In the meanwhile, I/O bound processes finish I/O and wait for CPU, thus leaving the I/O devices idle. The CPU bound process releases the CPU as it goes for an I/O. I/O bound processes have short CPU bursts, and they execute and go for I/O quickly. The CPU is idle till the CPU bound process finishes the I/O and gets hold of the CPU. The above cycle repeats. This is called the convoy effect. "

Convey effect

Transmission effect

Convoy effect

Score 0 of 1 2. The difference between the time of submission and the time of first response:

Execution

Start

Feedback: Start time is the time taken between the creation of a thread and the first time it is put on the CPU.

Response

Waiting

Score 0 of 1 3. The dispatcher is a module that gives control of the _____ to the process selected by the ___________ scheduler.

CPU, long-term

CPU, short-term

CPU, mid-term

Hardware, mid-term

Feedback:" The dispatcher is a component involved in the CPU scheduling function. It is the module that gives control of the CPU to the process selected by the short-term scheduler. The dispatcher should be as fast as possible, given that it is invoked during every process switch. The time it takes for the dispatcher to stop one process and start another is known as the dispatch latency.

Score 0 of 1 4. Preemptive scheduling is only possible on a hardware that supports a _____________ interrupt.

Timer

Program

Hardware

Feedback: A hardware interrupt is an electronic alerting signal sent to the processor from an external device, which is either a part of the computer itself, such as a disk controller, or an external peripheral.

Software

Score 1 of 1 5. _______________ execution consists of alternate CPU (Central Processing Unit) execution and I/O (Input / Output) wait.

Program

Process

Feedback:Right choice. Process execution consists of alternate CPU (Central Processing Unit) execution and I/O (Input / Output) wait. A cycle of these two events repeats till the process completes execution. Process execution begins with a CPU burst followed by an I/O burst and then another

CPU burst and so on. Eventually, a CPU burst will terminate the execution. An I/O-bound job will have short CPU bursts, and a CPU-bound job will have long CPU bursts.

Memory

Code

Score 0 of 1 6. In round-robin scheduling, the ready queue is a _________ queue with new processes joining the __________ of the queue.

LIFO, head

Feedback:" The CPU scheduler allocates to each process in the ready queue one time slice at a time in a round-robin fashion. It picks processes from the head of the queue for allocating the CPU. The first process at the head of the queue gets to execute on the CPU at the start of the current time slice and is deleted from the ready queue. The process allocated the CPU may have the current CPU burst equal to the time slice, smaller than the time slice, or greater than the time slice. In the first two cases, the current process will release the CPU on its own and thereby the next process in the ready queue will be allocated the CPU for the next time slice. In the third case, the current process is preempted, stops executing, goes back, and joins the ready queue at the tail thereby making way for the next process."

LIFO, middle

FIFO, tail

FIFO, head

Score 0 of 1 7. Which algorithm produces most optimal scheduling scheme?

Priority scheduling

Short-job-first scheduling

First-come-first-serve

Feedback:A process that requests for the CPU first is allocated the CPU first. Hence, the name first come first serve. The FCFS algorithm is implemented by using a first-in-first-out (FIFO) queue

structure for the ready queue.

Multiple-processor scheduling

QUIZ 3

1. "Identify the following statements as True or False: 1. The processes executing in the operating system may be either dependent processes or co-operating processes.2. The processes executing in the operating system may be either implicit processes or explicit processes.3. The processes executing in the operating system may be either real-time processes or para real-time processes.4. The processes executing in the operating system may be either independent processes or co-operating processes."





Feedback:Right choice. A process is said to be independent if it cannot affect or be affected by the other processes executing in the system. Any process that does not share data with any other process is independent. On the other hand, a process is co-operating if it can affect or be affected by the other processes executing in the system. Clearly any process that shares data with other processes is a co-operating process.

Score 4 of 4 2. "Identify the following statemetns as True or False:1.The main objective of multiprogramming is to see that no process is running so as to maximize CPU utilization.2. The main objective of multiprogramming is to see that all processes are always running so as to maximize CPU utilization.3. The main objective of multiprogramming is to see that some process is always running so as to minimize CPU utilization.

4. The main objective of multiprogramming is to see that some process is always running so as to maximize CPU utilization."





Feedback:Right choice. The main objective of multiprogramming is to see that some process is always running so as to maximize CPU utilization, whereas in the case of time sharing, the CPU is to be switched between processes frequently, so that users interact with the system while their programs are executing.

Score 4 of 4 3. Match the following points of Part A with Part B:


Throughput Number of processes completed per time unit

Number of processes completed per time unit

Turnaround Time

The interval of time between submission and completion of a process

The interval of time between submission and completion of a process

Waiting Time Sum of all the times spent by a process at different instances waiting in the ready queue

Sum of all the times spent by a process at different instances waiting in the ready queue

Response Time

The difference between time of submission and the time the first response occurs.

The difference between time of submission and the time the first response occurs.

UNIT 5

QUIZ 1

1. It is a part of program that accesses a shared resource (data structure or device) that must not be concurrently accessed by more than one process of execution.

Mediocre-section

Critical-section

Feedback:Right choice. A critical-section is a part of program that accesses a shared resource (data structure or device) that must not be concurrently accessed by more than one process of execution. When one process is executing in its critical-section, no other process is to be allowed to execute in its critical-section. Thus the execution of critical-sections by the processes is mutually exclusive in time. The critical-section problem is to design a protocol that the processes can use to co-operate. Each process must request permission to enter its critical-section.

Simple-section

Complicated-section

Score 0 of 1 2. The _______________ queue has finite length n; thus, at most n messages can reside in it.

High capacity

Unbounded capacity

Feedback: Unbounded capacity queue has potentially infinite length. Any number of messages can wait in it. The sender never blocks the messages.

Zero capacity

Bounded capacity

Score 1 of 1 3. In the direct-communication discipline, each process that wants to communicate must explicitly ________ the recipient or sender of the communication.

Identify

Verify

Name

Feedback:"Right choice. In the direct-communication discipline, each process that wants to communicate must explicitly name the recipient or sender of the communication. In this scheme, the send and receive primitives are defined as follows:Send (P, message). Send a message to process P.Receive (Q, message). Receive a message from process Q."

Block

Score 1 of 1 4. The synchronous communication method can be expanded easily into a full-featured ___________________ system.

Local procedure call

Remote procedure call

Feedback:Right choice. A Remote procedure call (RPC) system is based on the realization that a subroutine or procedure call in a single-process system acts exactly like a message system in which the sender blocks the message until it receives a reply. The message is then like a subroutine call, and the return message contains the value of the subroutine computed. The next logic step, therefore, is for concurrent processes to be able to call each other subroutines using RPC. RPCs can be used between processes running on separate computers to allow multiple computers to work together in a mutually beneficial way.

Remote call

Local call

Score 1 of 1 5. A link has some capacity that determines the number of messages that can reside in it _________________.

Temporarily

Feedback:Right choice. A link has some capacity that determines the number of messages that can reside in it temporarily. This property can be viewed as a queue of messages attached to the link.

Permanently

Completely

Randomly

Score 0 of 1 6. With ________________ communication, the messages are sent to and received from mailboxes.

Direct

Indirect

Verbal

Feedback:"Verbal communication is the most common of the many types of communication. Verbal means you talk to each other. Uttering words, phrases, or sentences is considered a verbal communication."

Non-verbal

QUIZ 2

1. "Identify which of the following statements are True or False 1. In an instruction having the format ‘TSL ACC, IND’, ACC is a/an access register and IND is a memory location used as a flag.2. In an instruction having the format ‘TSL ACC, IND’, ACC is a/an processor register and IND is a memory location used as a flag.3. In an instruction having the format ‘TSL ACC, IND’, ACC is a/an accumulator register and IND is a memory location used as a flag.4. In an instruction having the format ‘TSL ACC, IND’, ACC is a/an conditional register and IND is a memory location used as a flag."


Feedback: Whenever an instruction is executed, the contents of IND are copied to ACC and IND is set to ‘N’, which implies that the process is in its critical section. If the process comes out of its critical section, IND is set to ‘F’. Hence, the TSL instruction is executed only if IND has the value ‘F.’




Score 4 of 4 2. "Identify which of the following statements are True or False 1. Zero capacity queue has maximum length 0; thus, the link cannot have any messages waiting in it.2. Unbounded capacity queue has maximum length 0; thus, the link cannot have any messages waiting in it.3. Bounded capacity queue has potentially infinite length; thus, any number of messages can wait in it.4. Unbounded capacity queue has potentially infinite length; thus, any number of messages can wait in it."





Feedback:Right choice. Zero capacity queue has maximum length 0; thus, the link cannot have any messages waiting in it. Unbounded capacity queue has potentially infinite length; thus, any number of messages can wait in it. Bounded capacity queue has finite length n; thus, at most n messages can reside in it.

Score 0 of 4 3. "Identify which of the following statements are True or False 1. Processes that want to communicate must have a way to refer to each other. They can use either explicit communication or automatic communication.2. Processes that want to communicate must have a way to refer to each other. They can use either internal communication or external communication.3. Processes that want to communicate must have a way to refer to each other. They can use either direct communication or indirect communication.4. Processes that want to communicate must have a way to refer to each other. They can use either synchronous communication or asynchronous communication."





Feedback: In direct communication discipline, each process that wants to communicate must explicitly name the recipient or sender of the communication. In indirect communication, the messages are sent to and received from mailboxes (also referred to as ports). A mailbox can be viewed abstractly as an object into which messages can be placed by processes and from which messages can be removed.

Score 0 of 4 4. Match the points of Part A with part B:


Direct Communication

each process that wants to communicate must explicitly name the recipient or sender of the communication.

the messages are sent to and received from mailboxes (also referred to as ports).

Indirect Communication

the messages are sent to and received from mailboxes (also referred to as ports).

each process that wants to communicate must explicitly name the recipient or sender of the communication.

Bounded capacity

The queue has finite length n; thus, at most n messages can reside in it.

The queue has finite length n; thus, at most n messages can reside in it.

Critical Section a part of program that accesses a shared resource (data structure or device) that must not be concurrently accessed by more than one process of execution.

a part of program that accesses a shared resource (data structure or device) that must not be concurrently accessed by more than one process of execution.

QUIZ 3

1. Which types of messages can be sent by a process ?

Direct, indirect

Fixed-sized, variable-sized

Feedback:

Right Choice. If only fixed-sized messages can be sent, the physical implementation is straight forward. This restriction, however, makes the task of programming more difficult. On the other hand, variable-sized messages require a more complex physical implementation, but the programming task becomes simpler.

Symmetric, asymmetric

Automatic, explicit

Score 2 of 2 2. IPC provides a mechanism for allowing processes to do two things with their actions?

Create, save

Open, close

Merge, transfer

Communicate, synchronize

Feedback:Right choice. Communication of co-operating processes’ shared-memory environment requires that these processes share a common buffer pool. Another way to achieve the same effect is for the operating system to provide the means for co-operating processes to communicate with each other through an inter-process-communication (IPC) facility.

Score 2 of 2 3. An algorithm developed for solving a _______________ problem for n processes is also called _________ algorithm.

Critical-section, bakery

Feedback:Right Choice. Bakery algorithm is called so because it is based on the scheduling algorithm commonly used in bakeries, ice-cream stores, meat markets, motor-vehicle registries, and other locations where order must be made out of chaos.

Mediocre-section, bakery

Simple-section, bakery

Complicated-section, bakery

Score 0 of 2 4. A mailbox may be owned by which of the following?

Computer, software developer

User, server

Process, system

Process, server

Feedback:If the mailbox is owned by a process (that is, the mailbox is attached to or defined as part of the process), then we distinguish between the owner (who can only receive messages through this mailbox) and the user of the mailbox (who can only send messages to the mailbox). On the other hand, a mailbox that is owned by the operating system has an existence of its own. It is independent, and is not attached to any particular process.

UNIT6

QUIZ 1

1. To avoid _____ and _____, the system must ensure that a process that requests for a resource does not hold on to another.

Open, close

Stop, move

Hold, wait

Feedback:"Right choice. There can be two approaches to this scheme:1) a process requests for and gets allocated all the resources it uses before execution begins.2) a process can request for a resource only when it does not hold on to any other.Algorithms based on these approaches have poor resource utilization. This is because resources get locked with processes much earlier than they are actually used and hence are not available for others to use as in the first approach. The second approach seems applicable only when there

is assurance about reusability of data and code on the released resources. The algorithms also suffer from starvation since popular resources may never be freely available."

Restart, finish

Score 1 of 1 2. System _______________ when deadlocks are ignored and numerous processes enter into deadlock.

Reboots

Crashes

Feedback:"Right choice. If the problem of deadlocks is ignored totally, that is, to say the system does not ensure that a deadlock does not occur and also does not provide for recovery from deadlock and such a situation arises, then there is no way out of the deadlock. Eventually, the system may crash because more and more processes request for resources and enter into deadlock."

Closes

Restarts

Score 0 of 1 3. If there are ______________ instances of resources types, then a cycle does not necessarily imply a deadlock.

Two

No

Feedback:" Here, a cycle is a necessary condition, but not a sufficient condition for the existence of a deadlock. "

Single

Multiple

Score 1 of 1 4. If a resource allocation graph has no cycles (a closed loop in the direction of the edges), then the system is ____ in a state of deadlock.

Partially

Completely

Not

Feedback:Right choice. Resource allocation graph has no cycle. But, if there are cycles, then a deadlock may exist. If there are only single instances of each resource type, then a cycle in a resource allocation graph is a necessary and sufficient condition for existence of a deadlock.

Definitely

Score 1 of 1 5. Which of the following allocation graph is a directed graph consisting of vertices and directed edges?

Data

Resource

Feedback:Right choice. The vertex set is partitioned into two types: a subset representing processes and another subset representing resources. A directed edge from a process to a resource (Pi -> Rj) signifies a request from a process Pi for an instance of the resource Rj, and Pi is waiting for Rj. A directed edge from a resource to a process (Rj -> Pi) indicates that an instance of the resource Rj has been allotted to process Pi. Thus, a resource allocation graph consists of vertices, which include resources and processes, and directed edges, which consist of request edges and assignment edges.

Space

Memory

Score 0 of 1 6. Resources are of several types, each type having ______________ instances of the resource.

Identical

Different

Feedback:" For example, the system may have 2 dot matrix printers and 1 line printer. Here, the resource type of dot matrix printer has 2 instances whereas there is a single instance of type line printer."

Varying

Similar

Score 0 of 1 7. ____________ occurs when we have a set of processes [not necessarily all the processes in the system], each holding some resources, each requesting some resources, and none of them is able to obtain what it needs.

Block

Feedback: Several processes compete for a finite set of resources in a multi-programmed environment. A process requests for resources that may not be readily available at the time of the request. In such a case, the process goes into a wait state. It may happen that this process may never change state because the requested resources are held by other processes, which themselves are in a wait state. This situation is called a deadlock.

Deadlock

Stoppage

Starvation

QUIZ 2

1. "Identify which of the following statements are True or False1. The data allocation graph algorithm is not applicable where resources have single instances.2. The memory allocation graph algorithm is not applicable where resources have single instances.3. The memory allocation graph algorithm is not applicable where resources

have multiple instances.4. The resource allocation graph algorithm is not applicable where resources have multiple instances."



Feedback:Right choice. The resource allocation graph algorithm is not applicable where resources have multiple instances. In such cases, Banker’s algorithm is used.



Score 4 of 4 2. Which one of the following is not a basic approach to handle deadlocks? A. Prevention B. Avoidance C. Detection D. Termination

Only A

Only B

Only C

Only D

Feedback:Right choice. Prevention, avoidance and detection are the three basic approaches to handle deadlocks.

Score 4 of 4 3. "Identify which of the following statements are True or False 1.If the system ensures that a deadlock cannot be prevented or a deadlock cannot be avoided, then a deadlock may occur.2. If the system does not ensure that a deadlock cannot be prevented or a deadlock cannot be avoided, then a deadlock might not occur.3. If the system does not ensure that a deadlock cannot be prevented or a deadlock cannot be avoided, then a deadlock may occur.

4. If the system ensures that a deadlock cannot be prevented or a deadlock cannot be avoided, then a deadlock might not occur. "

Only statement 2 is true

Statements 1 and 3 are true



Feedback:"Right choice. If the system does not ensure that a deadlock cannot be prevented or a deadlock cannot be avoided, then a deadlock may occur. In case a deadlock occur, the system must:1) Detect the deadlock2) Recover from the deadlock"

QUIZ 3

1. If no cycle exists, what are the states of a system and requests respectively?

Safe, granted

Feedback:Right choice. If no cycle exists, the system is in a safe state and requests can be granted. If a cycle exists, the system is in an unsafe state and hence, in a deadlock. In such a case, requests should not be granted.

Unsafe, revoked

Running, granted

Debugging, granted

Score 0 of 2 2. Name the two types of edges of resource allocation graph.

Directed, indirected

Feedback:

When a process makes an actual request for a resource, the corresponding claim edge is converted to a request edge Pi -> Rj. Similarly, when a process releases a resource after use, the assignment edge Rj -> Pi is reconverted to a claim edge Pi -> Rj.

Request, assignment

Buffered, assignment

Request, buffered

Score 2 of 2 3. If a resource allocation graph does not have a cycle, then the system is ____ in deadlock. But, if there is a cycle, then the system may ____ in a deadlock.

Partially, not

Definitely, not

Completely, not

Not, be

Feedback:"Right choice. Resource allocation graph has no cycle. But, if there are cycles, then a deadlock may exist. If there are only single instances of each resource type, then a cycle in a resource allocation graph is a necessary and sufficient condition for existence of a deadlock."

Score 2 of 2 4. No preemption states that _____________ allocated to processes cannot be _______________.

Resources, preempted

Feedback:Right Choice. To ensure that No preemption condition does not hold, resources could be preempted. When a process requests for a resource, it is allocated the resource if it is available. If it is not available, then a check is made to see if the process holding the wanted resource is also waiting for additional resources. If so, the wanted resource is preempted from the waiting process and allotted to the requesting process.

Data, preempted

Program, preempted

Resources, non-preempted

UNIT 7

QUIZ 1

1. _______________ allocate the largest hole available. The entire list has to be searched for the biggest hole.

Best-fit

Worst-fit

Feedback:Right choice. The size of a process is very rarely an exact size of a hole allocated. The worst-fit allocation is the worst among the three and is seldom used.

First-fit

One-fit

Score 1 of 1 2. _______________ requires that there are many processes residing in memory so that the CPU can switch between processes.

Multiuser

Multithreading

Multitasking

Multiprogramming

Feedback:Right choice. In this case, the user area of memory is divided into partitions. The simplest way is to divide the user area into fixed number of partitions, each holding a single user process. Thus, the degree of multi-programming is equal to the number of partitions.

Score 0 of 1 3. __________ are swapped between the main memory and the backing store when priority based CPU scheduling is used.

Variables

Data

Processes

Registers

Feedback: Processes are swapped between the main memory and the backing store when priority based CPU scheduling is used. The arrival of a high priority process will be a lower priority process that is executing to be swapped out to make way for a swap in. The swapping in this case is sometimes referred to as roll out / roll in.

Score 1 of 1 4. Every time a time slice _____________, a process is swapped out and another is swapped in.

Resumes

Expires

Feedback:Right choice. The memory manager that does the swapping is fast enough to provide a process in memory for the CPU to execute. The duration of a time slice is carefully chosen so that it is sufficiently large enough as compared to the time required for swapping.

Creates

Begins

Score 1 of 1 5. Which register contains a value to be added to every address generated by the CPU?

Relocation

Feedback:Right choice. The relocation register contains a value to be added to every address generated by

the CPU for a user process at the time it is sent to the memory for a fetch or a store.

Data

Index

Memory data

Score 1 of 1 6. The logical address is also sometimes referred to as a ____________ address.

Absolute

Virtual

Feedback:Right choice. The set of logical addresses generated by the CPU for a program is called the logical address space. The set of all physical addresses corresponding to a set of logical addresses is called the physical address space. At run time / execution time, the virtual addresses are mapped to physical addresses by the memory management unit (MMU).

Base

Memory

QUIZ 2

1. "Identify which of the following statements are True or False 1. TLBs are main registers that allow a parallel search of a key item.2. TLBs are address registers that allow a single search of a key item.3. TLBs are associative registers that allow a single search of a key item.4. TLBs are associative registers that allow a parallel search of a key item."'


Feedback: Initially, the TLBs contain only a few or no entries. When a logical address generated by the CPU is to be mapped to a physical address, the page number is presented as input to the TLBs. If the page number is found in the TLBs, the corresponding frame number is made available so

that memory can be accessed. If the page number is not found, then a memory reference to the page table in main memory is made to fetch the corresponding frame number. This page number is then added to the TLBs so that next time, a mapping for the same address finds an entry in the table. Thus, a hit will reduce one memory access and speed up address translation.

All statements are true.



Score 0 of 4 2. "Identify which of the following statements are True or False1.Memory management using paging provides an entire different view of memory – User / logical.2. Memory management using paging provides no view of memory.3. Memory management using paging provides two entirely different views of memory – User / logical / virtual view and the actual / physical view.4. Memory management using paging provides three entirely different views of memory – User / logical view, User / virtual view, and the actual / physical view. "


Statements 1 and 3 are true "Not the right choice. Memory management using paging provides two entirely different views of memory – User / logical / virtual view and the actual / physical view. Both are not the same. In fact, the user’s view is mapped on to the physical view. How do users visualize memory? Users prefer to view memory as a collection of variable sized segments."


Feedback: Memory management using paging provides two entirely different views of memory – User / logical / virtual view and the actual / physical view. Both are not the same. In fact, the user’s view is mapped on to the physical view. How do users visualize memory? Users prefer to view memory as a collection of variable sized segments.


Score 0 of 4

3. "Match the points of Part A with Part B:


Logical address

An address generated by the CPU

Also referred as logical address

Virtual address

Also referred as logical address An address generated by the CPU

Physical address space

The set of all physical addresses corresponding to a set of logical address

The set of all physical addresses corresponding to a set of logical address

Logical address space

The set of logical addresses generated by the CPU for a program

The set of logical addresses generated by the CPU for a program

QUIZ 3

1. Hardware implementation of a ______ is done in a number of ways. In the simplest case, the page table is implemented as a set of dedicated ____________ registers.

Page table, high-speed

Frame, high-speed

Feedback: Hardware implementation is satisfactory only if the page table is small. Modern computers allow the page table size to be very large. In such cases, the page table is kept in main memory and a pointer called the page-table base register (PTBR) helps index the page table.

Page table, low-speed

Frame, low-speed

Score 2 of 2 2. Name the memories that are divided into fixed sized blocks called frames and into blocks of the same size called pages respectively.

Secondary, physical

Physical, logical

Feedback:Right Choice. Allocation of main memory to processes for execution involves mapping pages to frames. A logical address generated by the CPU consists of two parts: Page number (p) and a page offset (d). The page number is used as an index into a page table. The page table contains the base address of each frame in physical memory. The base address is combined with the page offset to generate the physical address required to access the memory unit.

Logical, secondary

Logical, physical

Score 0 of 2 3. Compaction may not always be __________ since it involves ______________.

Possible, reallocation

Feedback: If relocation is static at load time, then relocation and compaction is not possible. Compaction is possible only if relocation is done at runtime. Even though compaction is possible, the cost involved in relocation is to be considered. The position where the hole is to be created during compaction depends on the cost of relocating the processes involved.

Acceptable, relocation

Acceptable, reallocation

Possible, relocation

Score 0 of 2 4. How many bytes would be free if a process were allocated a hole?

1,2

2,1

1, 0

0, 1

Feedback: There are situations where only a few bytes say 1 or 2 would be free if a process were allocated a hole. Then, the cost of keeping track of this hole will be high. In such cases, this extra bit of hole is also allocated to the requesting process. This is known as internal fragmentation.

Score 0 of 2 5. The relocation register contains a value to be added to every address generated by the CPU for a user process at the time it is sent to the memory for two purposes. What are those?

Open, close

Feedback:" Logical addresses range from 0 to a maximum (MAX) and the corresponding physical addresses range from(R + 0) to (R + MAX) for a base value of R. User programs generate only logical addresses that are mapped to physical addresses before use."

Stop, move

Fetch, store

Open, store

UNIT 8

QUIZ 1

1. The high paging activity is called:

Segmentation

Demand paging

Feedback: Initially, a process starts executing with no pages in memory. The very first instruction generates a page fault, and a page is brought into memory. After a while, all pages required by the process are in memory with a reference to each page generating a page fault and getting a page into memory. This is known as pure demand paging.

Thrashing

Fragmentation

Score 1 of 1 2. Implementation of FIFO algorithm is __________.

Difficult

Simple

Feedback:Right choice. Implementation of FIFO algorithm is simple. A FIFO queue can hold pages in memory with a page at the head of the queue becoming the victim and the page swapped in joining the queue at the tail.

Mediocre

Partially difficult

Score 0 of 1 3. When a process is to be executed, only that page of the process which needs to be currently executed is swapped into memory. This method is:

Demand paging

Loader paging

Feedback:" Demand paging is similar to paging with swapping. Thus, only necessary pages of the process are swapped into memory, thereby decreasing swap time and physical memory requirement. "

Fast paging

Normal paging

Score 0 of 1 4. In which paging, a page is never brought into memory until required?

Normal

Feedback:Initially, a process starts executing with no pages in memory. The very first instruction generates a page fault, and a page is brought into memory. After a while, all pages required by the process are in memory with a reference to each page generating a page fault and getting a page into memory. This is known as pure demand paging.

Pure demand

Fast

Loader

Score 0 of 1 5. A working set window is a parameter that maintains the most recent __________ references.

Frame

Page

Space

Feedback: A working set window is defined as a parameter that maintains the most recent page references. This set of most recent page references is called the working set. An active page always finds itself in the working set. Similarly, a page not used will be droped off the working set time units after its last reference. Thus, the working set is an approximation of the program’s locality.

Memory

Score 0 of 1 6. When a ________________ page-replacement policy is used instead of a global policy, thrashing is limited to a process only.

Multiple

Private

Global

Feedback:To prevent thrashing, a process must be provided as many frames as it needs. A working-set strategy determines how many frames a process is actually using by defining what is known as a locality model of process execution. The locality model states that as a process executes, it moves from one locality to another, where a locality is a set of active pages used together. These localities are strictly not distinct and overlap.

Local

QUIZ2

1. "Identify which of the following statements are True or False1. To determine the number of page frames for a particular reference string and a page-replacement algorithm, the number of pages available to the process needs to be known.2. To determine the number of page faults for a particular reference string and a page-replacement algorithm, the number of pages available to the process needs to be known.3. To determine the number of page faults for a particular reference string and a page-replacement algorithm, the number of frames available to the process needs to be known.4. To determine the number of page frames for a particular reference string and a page-replacement algorithm, the number of faults available to the process needs to be known."



Feedback:Right choice. To determine the number of page faults for a particular reference string and a page replacement algorithm, the number of available frames to the process needs to be known. As the number of available frames increases, the number of page faults decreases. If available frames are 3, then there would be only 3 page faults, one for each page reference. On the other hand, if only 1 frame is available, then there would be 11 page faults, one for every page reference.



Score 0 of 4 2. "Identify which of the following statements are True or False1. No frame in memory is associated with a dirty bit that is reset when the page is brought into memory.2. Each frame in memory is associated with a dirty bit that is reset when the page is brought into memory.3. Each frame in memory is associated with several dirty bits that is reset when the page is brought into memory.4. Each frame in memory is associated with a dirty bit that is reset when the page is at fault. "





Feedback:" When a page fault occurs and no free frame is present,then a swap out and a swap in occur. A swap out is not always necessary.Only a victim that has been modified needs to be swapped out.If not, the frame can be over written by the incoming page.This will save time required to service a page fault and is implemented by the use of a dirty bit.

Score 0 of 4 3. Match the points of Part A with Part B:

MatchCorrect Answer

User answer Feedback

Refers to high paging activity Thrashing LRU

Replace the page that has not been used for the longest period of time

LRU Thrashing

The algorithm is to replace the page that will not be used for the longest period of time to come.

Optimal FIFO

When a page replacement is required the oldest page in memory is the victim.

FIFO Optimal

QUIZ 3

1. When thrashing in page fault is set ____. This means a process needs more ________.

High, frames

Low, space

Feedback:If page fault rate is low, the process may have more than necessary frames to execute. So, upper and lower bounds on page faults can be defined. If the page fault rate exceeds the upper bound, another frame is allocated to the process. If it falls below the lower bound, a frame already allocated can be removed. Thus, monitoring the page fault rate helps prevent thrashing.

High, space

Low, memory

Score 0 of 2

2. When CPU utilization ___________ below a certain threshold, the operating system increases the degree of ______________ by bringing in a new process to increase CPU utilization.

Increases, multiprogramming

Drops, multiprogramming

Increases, multitasking

Decreases, multitasking

Feedback: Paging activity increases with longer queues at the paging device but CPU utilization drops. As CPU utilization drops, the job scheduler increases the degree of multiprogramming by bringing in a new process. This only increases paging activity to further decrease CPU utilization. This cycle continues. Thrashing has set in and throughput drops drastically.

Score 0 of 2 3. Which is used to keep track of the page numbers? Which always put on top of the stack?

Database, page referenced

Queue, page referenced

Frame, page stored

FeedbackA stack is used to keep track of the page numbers. A page referenced is always put on top of the stack. Therefore, the top of the stack is the most recently used page and the bottom of the stack is the LRU page.

Stack, page referenced

Score 2 of 2 4. This type of algorithm uses the time when a page was brought into memory (looks back), whereas the other type of algorithm uses the time when a page is to be used in future (looks ahead). Name the two algorithms.

FIFO, optimal

Feedback:Right Choice. The first-in-first-out page replacement algorithm is the simplest page replacement algorithm. When a page replacement is required, the oldest page in memory is the victim. An optimal page replacement algorithm produces the lowest page fault rate of all algorithms. The algorithm is to replace the page that will not be used for the longest period of time to come.

LIFO, optimal

FCFS, optimal

LRU, optimal

Score 2 of 2 5. Which of the following statement is true?

As the number of available frames increase the number of page faults increase.

As the number of available frames decrease the number of page faults decrease.

As the number of available frames increase the number of page faults decrease.

Feedback:Right choice. To determine the number of page faults for a particular reference string and a page replacement algorithm, the number of available frames to the process needs to be known. As the number of available frames increase the number of page faults decrease. If available frames are 3, then there would be only 3 page faults, one for each page reference. On the other hand, if there is only 1 available frame then there would be 11 page faults, one for every page reference.

As the number of available frames decrease the number of page faults increase.

MIT201 QUIZES

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