Operating Systems (Core Concepts) Flashcards

Question 1

Operating System (OS)

Accepted Answer

Software that acts as an intermediary between computer hardware and the user.

Question 2

Kernel

Accepted Answer

(Core of the OS) The program that executes at all times and manages system resources.

Question 3

System Call

Accepted Answer

The programmatic way a computer program requests a service from the kernel of the OS.

Question 4

Process

Accepted Answer

A program in execution; the unit of work in a modern time-sharing system.

Question 5

Process Control Block (PCB)

Accepted Answer

A data structure in the OS kernel containing the information needed to manage a particular process.

Question 6

Context Switch

Accepted Answer

The process of saving the state of the currently running process and loading the state of the next process to run.

Question 7

Thread

Accepted Answer

A basic unit of CPU utilization, consisting of a program counter, a stack, and a set of registers.

Question 8

User Thread vs Kernel Thread

Accepted Answer

User threads are managed without kernel support; kernel threads are supported and managed directly by the OS.

Question 9

Multiprogramming

Accepted Answer

Keeping multiple processes in memory simultaneously to maximize CPU utilization.

Question 10

Time-sharing (Multitasking)

Accepted Answer

A logical extension of multiprogramming where the CPU executes multiple jobs by switching among them frequently.

Question 11

CPU Scheduler

Accepted Answer

Selects a process from the ready queue to execute on the CPU.

Question 12

Dispatcher

Accepted Answer

Gives control of the CPU to the process selected by the short-term scheduler (involves context switching).

Question 13

Preemptive Scheduling

Accepted Answer

The OS can interrupt a currently running process and move it back to the ready queue.

Question 14

Non-preemptive Scheduling

Accepted Answer

Once the CPU has been allocated to a process, the process keeps the CPU until it releases it (terminates or blocks).

Question 15

First-Come, First-Served (FCFS)

Accepted Answer

A non-preemptive scheduling algorithm where the process that requests the CPU first is allocated the CPU first.

Question 16

Shortest-Job-First (SJF)

Accepted Answer

A scheduling algorithm that associates each process with the length of its next CPU burst; optimal for minimizing average waiting time.

Question 17

Shortest-Remaining-Time-First (SRTF)

Accepted Answer

The preemptive version of Shortest-Job-First (SJF).

Question 18

Round Robin (RR) Scheduling

Accepted Answer

A preemptive scheduling algorithm where each process gets a small unit of CPU time (time quantum), usually 10-100 ms.

Question 19

Time Quantum

Accepted Answer

The maximum amount of continuous time a process is allowed to run in Round Robin scheduling.

Question 20

Priority Inversion

Accepted Answer

A scenario where a lower-priority process holds a lock needed by a higher-priority process.

Question 21

Priority Inheritance

Accepted Answer

A solution to priority inversion where a lower-priority process temporarily inherits the priority of a higher-priority process waiting for its resource.

Question 22

Race Condition

Accepted Answer

A situation where the output is dependent on the sequence or timing of uncontrollable events (like thread execution order).

Question 23

Critical Section

Accepted Answer

A segment of code where shared memory/resources are accessed and modified.

Question 24

Mutual Exclusion

Accepted Answer

If process P is executing in its critical section, then no other processes can be executing in their critical sections.

Question 25

Mutex Lock

Accepted Answer

A synchronization tool used to protect critical sections and prevent race conditions (boolean variable).

Operating Systems (Core Concepts)

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