C191 Operating Systems

wait

- A parent process calling _____ system call will be suspended until children processes terminate. - returns the process identifier of a terminated child - atomic operation permissible on semaphores

stub

- RPC provides a separate one for each remote procedure. - transmits the message to the server where the server side stub receives the message and invokes procedure on the server side - packs the parameters into a form transmittable over the network - locates the port on the server

What is operating system?

- collection of programs that manages hardware resources - system service provider to the application programs - link to interface the hardware and application programs

kernel

- program that constitutes the central core of the operating system - first part of operating system to load into memory during booting - remains in the memory during the entire computer session

a) shared data structures b) procedures that operate on shared data structure c) synchronization between concurrent procedure invocation

A monitor is a module that encapsulates

- normal exit - fatal error - killed by another process

A process can be terminated due to

ready, short term

A process is selected from the ______ queue by the ________ scheduler, to be executed.

PID of child process

A process stack does not contain

Remote Procedure Call

A process that is based on IPC mechanism which executes on different systems and can communicate with other processes using message based communication, is called

that can not drop below zero

A semaphore is a shared integer variable

each process is blocked and will remain so forever

A set of processes is deadlock if

only one task at a time

A single thread of control allows the process to perform:

many very short CPU bursts

An I/O bound program will typically have :

receive/send messages to cell body

An IPC facility provides at least two operations :

the predicted next CPU burst

An SJF algorithm is simply a priority algorithm where the priority is :

Automatic buffering

Bounded capacity and Unbounded capacity queues are referred to as :

Normally

Cascading termination refers to termination of all child processes before the parent terminates ______

DMA is used for :

High speed devices(disks and communications network)

In the layered approach of Operating Systems :

Highest Layer(N) is the User interface

Sending signals to CPU through system bus

How does the Hardware trigger an interrupt ?

Executing a system call

How does the software trigger an interrupt ?

log file

If a process fails, most operating system write the error information to a

mutual exclusion

If a process is executing in its critical section, then no other processes can be executing in their critical section. This condition is called

empty,little

If all processes I/O bound, the ready queue will almost always be ______ and the Short term Scheduler will have a ______ to do.

Process Identifier

In UNIX, each process is identified by its :

Zero, A nonzero integer

In UNIX, the return value for the fork system call is _____ for the child process and _____ for the parent process.

fork

In Unix, Which system call creates the new process?

more than one process resides in the memory

In a multiprogramming environment :

there is a mailbox to help communication between P and Q

In indirect communication between processes P and Q :

a) address space and global variables b) open files c) pending alarms, signals and signal handlers

In operating system, each process has its own

currently running process

In priority scheduling algorithm, when a process arrives at the ready queue, its priority is compared with the priority of

When a process goes from the running state to the waiting state

In the following cases non - preemptive scheduling occurs :

the sending process sends the message and resumes operation

In the non blocking send :

communicate with one another without resorting to shared data

Message passing system allows processes to :

can be fixed or variable sized

Messages sent by a process :

both mutex locks and binary semaphores

Mutual exclusion can be provided by the

hybrid kernel

OS X has _________

it can lead to some low priority process waiting indefinitely for the CPU

One of the disadvantages of the priority scheduling algorithm is that :

multilevel queue scheduling algorithm

Process are classified into different groups in

both hardware and software level

Process synchronization can be done on

overloading the system by creating a lot of sub-processes

Restricting the child process to a subset of the parent's resources prevents any process from

- increase CPU utilization and thourghput - decrease the turnaround and waiting time

Scheduling is done so as to :

Ready state

Suppose that a process is in "Blocked" state waiting for some I/O service. When the service is completed, it goes to the : In a time-sharing operating system, when the time slot given to a process is completed, the process goes from the running state to the :

Data Structure

The Process Control Block is:

Program counter

The address of the next instruction to be executed by the current process is provided by the

be a duplicate of the parent process

The child process can :

Zombie

The child process completes execution,but the parent keeps executing, then the child process is known as :

the number of processes in memory

The degree of multiprogramming is:

Process Table

The entry of all the PCBs of the current processes is in:

bootstrap program

The initial program that is run when the computer is powered up is called :

communication link

The link between two processes P and Q to send and receive messages is called :

Throughput

The number of processes completed per unit time is known as

Have some process running at all times

The objective of multiprogramming is to :

block

The only state transition that is initiated by the user process itself is :

assigning ready processes to CPU

The portion of the process scheduler in an operating system that dispatches processes is concerned with

The frequency of their execution

The primary distinction between the short term scheduler and the long term scheduler is

knowing the length of the next CPU request

The real difficulty with SJF in short term scheduling is :

the current activity of the process

The state of a process is defined by:

Preemptive scheduling

The strategy of making processes that are logically runnable to be temporarily suspended is called : Round robin scheduling falls under this category:

CPU & I/O Burst

The two steps of a process execution are :

Round robin scheduling algorithm

Time quantum is defined in

Ports

To differentiate the many network services a system supports ______ are used.

a condition variable must be declared as condition

To enable a process to wait within the monitor,

machine-independent representation of data

To resolve the problem of data representation on different systems RPCs define _____________

Shortened; Lengthened

Under multiprogramming, turnaround time for short jobs is usually ________ and that for long jobs is slightly ___________

It selects which process has to be brought into the ready queue

What is a long-term scheduler ?

It selects which process to remove from memory by swapping

What is a medium-term scheduler ?

It selects which process has to be executed next and allocates CPU

What is a short-term scheduler ?

software generated interrupt caused by an error

What is a trap/exception ?

when process is scheduled to run after some execution

What is the ready state of a process?

It is removed from all queues

When a process terminates:

It is placed in an I/O queue

When the process issues an I/O request :

Shortest Job First

Which of the following algorithms tends to minimize the process flow time ?

A communication link can be associated with exactly two processes

Which of the following are TRUE for direct communication :

PCB queue

Which of the following do not belong to queues for processes ?

Translation lookaside buffer

Which of the following need not necessarily be saved on a context switch between processes ?

user level thread

Which one of the following can not be scheduled by the kernel?

a) power failure b) lack of paper in printer c) connection failure in the network

Which one of the following error will be handle by the operating system?

a) Saving the current state of the system b) Loading the interrupt handling code and executing it c) Once done handling, bringing back the system to the original state it was before the interrupt occurred

Which operation is performed by an interrupt handler ?

cooperating process

Which process can be affected by other processes executing in the system?

Uniprogramming, Multiprocessing

With _____________ only one process can execute at a time; meanwhile all other process are waiting for the processor. With ______________ more than one process can be running simultaneously each on a different processor.

- the sender blocks until the receiver receives the message - is referred to as a message system with no buffering

Zero capacity queue

semaphore

a synchronization tool

Scheduling is :

allowing a job to use the processor

Inter process communication :

allows processes to communicate and synchronize their actions without using the same address space

An interrupt vector

an address that is indexed to an interrupt handler

DTrace

facility dynamically adds probes to a running system, both in user processes and in the kernel

turnaround time

interval from the time of submission of a process to the time of completion is termed as

to get and execute the next user-specified command

main function of the command interpreter

ready queue

processes that are residing in main memory and are ready and waiting to execute are kept on a list called

System calls

provides the interface to access OS services

In an interrupt driven input/output :

the CPU receives an interrupt when the device is ready for the next byte

In a programmed input/output(PIO) :

the CPU uses polling to watch the control bit constantly, looping to see if device is ready

In a memory mapped input/output :

the CPU writes one data byte to the data register and sets a bit in control register to show that a byte is available

multiprogramming systems

the FCFS algorithm is particularly troublesome for ____________

Dispatch latency is :

the time to stop one process and start running another one

Turnaround time

the total time from the completion till the submission of a process

Waiting time

the total time spent in the ready queue

Response time

the total time taken from the submission time till the first response is produced

dispatcher

this module gives control of the CPU to the process selected by the short-term scheduler