D686 - Operating Systems - Section 2

Chapter 3-7

The convention in modern operating systems and compilers is that the ____ of a process contains temporary data such as function parameters, return addresses, and local variables.

stack

A process control block ____.

contain a process’ states

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

An interrupt has occurred or an I/O operation the process is waiting for has completed.

job

A set of commands or processes executed by a batch system.

user programs

User-level programs, as opposed to system programs.

task

A process, a thread activity, or, generally, a unit of computation on a computer.

process

A program loaded into memory and executing

program counter

A CPU register indicating the main memory location of the next instruction to load and execute.

text section

The executable code of a program or process.

data section

The data part of a program or process; it contains global variables.

heap section

The section of process memory that is dynamically allocated during process run time; it stores temporary variables.

stack section

The section of process memory that contains the stack; it contains activation records and other temporary data.

activation record

A record created when a function or subroutine is called; added to the stack by the call and removed when the call returns. Contains function parameters, local variables, and the return address.

executable file

A file containing a program that is ready to be loaded into memory and executed.

state

The condition of a process, including its current activity as well as its associated memory and disk contents.

process control block

A per-process kernel data structure containing many pieces of information associated with the process.

task control block

A per-process kernel data structure containing many pieces of information associated with the process.

thread

A process control structure that is an execution location. A process with a single ______ executes only one task at a time, while a multi______ed process can execute a task per ______.

process scheduler

A scheduler that selects an available process (possibly from a set of several processes) for execution on a CPU.

degree of multiprogramming

The number of processes in memory.

parent

In a tree data structure, a node that has one or more nodes connected below it.

children

In a tree data structure, nodes connected below another node.

siblings

In a tree data structure, child nodes of the same parent.

I/O-bound process

A process that spends more of its time doing I/O than doing computations

CPU-bound process

A process that spends more time executing on CPU than it does performing I/O.

ready queue

The set of processes ready and waiting to execute.

wait queue

In process scheduling, a queue holding processes waiting for an event to occur before they need to be put on CPU.

dispatched

Selected by the process scheduler to be executed next.

CPU scheduler

Kernel routine that selects a thread from the threads that are ready to execute and allocates a core to that thread.

swapping

Moving a process between main memory and a backing store. A process may be swapped out to free main memory temporarily and then swapped back in to continue execution.

context

When describing a process, the state of its execution, including the contents of registers, its program counter, and its memory context, including its stack and heap.

state save

Copying a process's context to save its state in order to pause its execution in preparation for putting another process on the CPU.

state restore

Copying a process's context from its saved location to the CPU registers in preparation for continuing the process's execution.

context switch

The switching of the CPU from one process or thread to another; requires performing a state save of the current process or thread and a state restore of the other.

tree

A data structure that can be used to represent data hierarchically; data values in a ___ structure are linked through parent-child relationships.

process identifier (pid)

A unique value for each process in the system that can be used as an index to access various attributes of a process within the kernel.

cascading termination

A technique in which, when a process is ended, all of its children are ended as well.

zombie

A process that has terminated but whose parent has not yet called wait() to collect its state and accounting information.

orphan

The child of a parent process that terminates in a system that does not require a terminating parent to cause its children to be terminated.

interprocess communication (IPC)

Communication between processes.

shared memory

In interprocess communication, a section of memory shared by multiple processes and used for message passing.

message passing

In interprocess communication, a method of sharing data in which messages are sent and received by processes. Packets of information in predefined formats are moved between processes or between computers.

What is the valid test for determining if the bounded buffer is empty?

(in == out)

producer

A process role in which the process produces information that is consumed by a consumer process.

consumer

A process role in which the process consumes information produced by a producer process.

unbounded buffer

A buffer with no practical limit on its memory size.

bounded buffer

A buffer with a fixed size.

direct communication

In interprocess communication, a communication mode in which each process that wants to communicate must explicitly name the recipient or sender of the communication.

blocking

In interprocess communication, a mode of communication in which the sending process is blocked until the message is received by the receiving process or by a mailbox and the receiver blocks until a message is available. In I/O, a request that does not return until the I/O completes.

nonblocking

A type of I/O request that allows the initiating thread to continue while the I/O operation executes. In interprocess communication, a communication mode in which the sending process sends the message and resumes operation and the receiver process retrieves either a valid message or a null if no message is available. In I/O, a request that returns whatever data is currently available, even if it is less than requested.

synchronous

In interprocess communication, a mode of communication in which the sending process is blocked until the message is received by the receiving process or by a mailbox and the receiver blocks until a message is available. In I/O, a request that does not return until the I/O completes.

asynchronous

In I/O, a request that executes while the caller continues execution.

rendezvous

In interprocess communication, when blocking mode is used, the meeting point at which a send is picked up by a receive.

single-threaded

A process or program that has only one thread of control (and so executes on only one core at a time).

multithreaded

A term describing a process or program with multiple threads of control, allowing multiple simultaneous execution points.

user thread

A thread running in user mode.

kernel threads

Threads running in kernel mode.

thread control block (TCB)

a data structure in an operating system that stores information about a thread, including its identifier, state, CPU information, priority, and pointers to related threads

thread ID

unique identifier assigned to a thread by the operating system

thread state

the current condition or status of a thread in the system (e.g., running, waiting, blocked)

register contents

the current values stored in the CPU registers used by the thread

thread priority

the assigned importance level of a thread, determining its scheduling order compared to other threads

multicore

refers to a CPU architecture that integrates multiple processing cores onto a single chip, or within a single system, enabling parallel execution of tasks

data parallelism

a computational technique where subsets of identical data are distributed across multiple processing cores, each core performing the same operation simultaneously on its subset of data

task parallelism

a computational approach where tasks or threads are distributed across multiple processing cores, with each task executing a unique operation independently, often on different or related data sets

fork()

a system call that creates a new process by duplicating the existing process

exec()

a system call that replaces the current process with a new program

signal

a way to alert a process about an event

default signal handler

the built-in handler for signals unless a process uses its own

pthread_kill()

a function in the POSIX threads (Pthreads) library used to send a signal to a specific thread within the same process

asynchronous procedure call (APC)

a function a thread sets to run when it gets a certain notice

thread cancellation

ending a thread before it finishes

pthread_cancel()

a function that requests the cancellation of a specific thread in Pthreads

What is the role of a process in a computer system?

Executing user and system tasks

Which state is a process when it is paused and is not currently being executed?

Waiting

How does a context switch impact CPU performance?

It temporarily suspends the current process to switch to another.

What is the purpose of scheduling queues in process management?

To manage the order of process execution

What is the result of a fork() system call in Unix?

Creation of a child process

Which mechanism allows processes to work together without interfering with each other?

Communication through interprocess mechanisms

Which method involves processes exchanging data by sending and receiving messages?

Message passing

How does synchronization ensure proper process execution?

By preventing simultaneous access to shared resources

Which type of thread is managed directly by the operating system?

Kernel-level

What is a significant advantage of using multithreading in applications?

It increases responsiveness and resource sharing.

process synchronization

the coordination of processes to ensure they operate smoothly and efficiently without interfering with each other, especially when accessing shared resources or data

mutex

short for mutual exclusion, a lock that ensures only one process can access a critical section or resource at a time, preventing race conditions

semaphores

synchronization tools used to control access to shared resources by multiple processes

starvation

a situation where a process is perpetually denied access to resources because other processes continuously acquire them

circular wait

a condition where each process in a set is waiting for a resource held by another process in the same set, contributing to deadlock

fair resource allocation

a principle ensuring that all processes have fair access to resources, preventing starvation and ensuring balanced system performance

producer-consumer scenario

where one process produces data and another consumes it, requiring synchronization to ensure that the buffer used does not overflow or underflow

concurrency

the ability of an operating system to execute multiple processes simultaneously, improving performance and responsiveness

critical section

A section of code responsible for changing data that must only be executed by one thread or process at a time to avoid a race condition.

entry section

The section of code within a process that requests permission to enter its critical section.

exit section

The section of code within a process that cleanly exits the critical section.

remainder section

Whatever code remains to be processed after the critical and exit sections.

preemptive kernel

A type of kernel that allows a process to be preempted while it is running in kernel mode.

nonpreemptive kernels

A type of kernel that does not allow a process running in kernel mode to be preempted; a kernel-mode process will run until it exits kernel mode, blocks, or voluntarily yields control of the CPU.

mutex lock

A mutual exclusion lock; the simplest software tool for assuring mutual exclusion.

contended

A term describing the condition of a lock when a thread blocks while trying to acquire it.

uncontended

A term describing a lock that is available when a thread attempts to acquire it.