Operating systems: structure, services, system calls, process management, interprocess communication and synchronization (semaphores, critical-section problem). - One Line Questions

1. A deadlock occurs when: — A set of processes are blocked indefinitely, each holding a resource and waiting to acquire a resource held by another process in the set.
2. In the context of operating systems, what is a 'process'? — An instance of a program in execution.
3. A system call is best defined as: — A request made by a user to the operating system for a service.
4. What is a 'thread'? — A lightweight unit of execution within a process, sharing resources with other threads of the same process.
5. What does the term 'starvation' refer to in process scheduling? — A situation where a process is repeatedly denied CPU access and never gets to execute.
6. In the context of concurrency, what is a 'race condition'? — A situation where the outcome of concurrent operations depends on the unpredictable timing of their execution, leading to incorrect results.
7. What is a 'daemon' process in Unix-like operating systems? — A background process that performs system services.
8. A semaphore is a synchronization primitive that can be thought of as: — A counter used to control access to a shared resource.
9. Which of the following is a method for preventing deadlock? — Ensuring at least one of the four necessary conditions for deadlock cannot hold.
10. A mutex (mutual exclusion) lock is primarily used for: — Ensuring that only one thread can access a critical section at a time.
11. Which type of semaphore is initialized to 1 and is used to ensure mutual exclusion? — Binary Semaphore
12. The 'exec()' system call is used to: — Replace the current process image with a new program.
13. Which of the following is a classic example of a synchronization problem that can be solved using semaphores? — The Producer-Consumer problem
14. The `signal()` operation on a semaphore (also known as V operation) typically: — Increments the semaphore value and potentially unblocks a waiting process.
15. What is the main challenge in implementing a Round Robin scheduling algorithm? — Determining the optimal time quantum.
16. Which system call is typically used to create a new process? — fork()
17. What is the main advantage of kernel-level threads over user-level threads? — Can run in parallel on multi-core processors without operating system intervention for each thread.
18. Which scheduling algorithm aims to minimize the average waiting time by executing the process with the smallest execution time first? — Shortest Job Next (SJN)
19. Which system call is used by a process to terminate itself? — exit()
20. What is the primary advantage of a microkernel design? — Increased reliability and maintainability as services run as separate processes.
21. Which of the following is a benefit of using threads over processes? — Lower overhead for creation and context switching.
22. The `wait()` operation on a semaphore (also known as P operation) typically: — Decrements the semaphore value and blocks the process if the value becomes negative.
23. In a microkernel architecture, which of the following services are typically moved out of the kernel into user space? — File system management and device drivers
24. A critical section is a segment of code that: — Accesses shared resources and must not be executed by more than one process at a time.
25. Which operating system service is responsible for allocating CPU time to different processes? — Process Management
26. Which operating system structure involves a monolithic kernel that includes most OS services within a single large process? — Monolithic Kernel
27. Which of the following operating system structures is known for its modularity and extensibility? — All of the above
28. Which of the following is a fundamental requirement for solving the critical-section problem? — Mutual Exclusion
29. Which of the following is NOT one of the four necessary conditions for deadlock? — Fairness
30. The Process Control Block (PCB) is a data structure that contains: — Information about the process's state, CPU registers, memory management, etc.
31. Interprocess Communication (IPC) is essential for: — Allowing processes to exchange data and synchronize their actions.
32. In a kernel-level thread implementation, which entity is directly managed by the operating system scheduler? — Threads
33. Which of the following is an example of a system call used for file management? — read()
34. Which of the following scheduling algorithms is non-preemptive? — First-Come, First-Served (FCFS)
35. Which of the following is NOT a typical state of a process? — Compiled
36. When a process makes an I/O request, it typically transitions to which state? — Waiting (or Blocked)
37. Which of the following synchronization techniques can lead to 'busy waiting' (also known as spinning)? — Spinlocks
38. Which IPC mechanism allows processes to send and receive messages without sharing memory directly? — Message Queues
39. What does 'context switching' refer to in an operating system? — Saving the state of a current process and loading the state of a new process to allow the CPU to resume execution.
40. What is the purpose of the 'Ready' state in process management? — The process is waiting to be assigned to the CPU.
41. What is a potential problem if a process is preempted while it is in its critical section? — Another process could enter the same critical section, violating mutual exclusion.
42. In a preemptive scheduling algorithm, a running process can be interrupted by the scheduler if: — A higher-priority process becomes ready to run.
43. A 'blocking send' in message passing IPC means: — The sending process is suspended until the message is received by the destination process.
44. What is the main purpose of process scheduling? — To maximize CPU utilization and minimize response time.
45. Which of the following best describes the primary role of an operating system? — To manage computer hardware and software resources, providing a platform for applications.
46. What is the main purpose of the 'sleep()' system call? — To allow a process to temporarily relinquish the CPU and go into a waiting state for a specified duration.
47. What is the primary function of a scheduler in an operating system? — To decide which process/thread gets to use the CPU next and for how long.
48. What is the primary goal of the 'Producer-Consumer' problem in concurrency? — To synchronize the actions of a producer process creating data and a consumer process using that data, using a shared buffer.
49. What is a key function of the operating system's kernel? — To provide core system services and manage hardware resources.
50. Which of the following is an example of a user-level thread implementation? — Solaris Green Threads (or similar user-level thread libraries)
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