Shulou(Shulou.com)06/03 Report--

What are the common operating system interview knowledge points, do you know? In order to make it easier for everyone to interview, the editor summed up the following content for you, hurry up and look down! There's got to be something you can't think of.

Summary of operating system knowledge points

1. The software system consists of various programs and data, including system software, supporting software and application software.

2. The design goal of the operating system: to facilitate the use of users, so that the computer system can work efficiently.

3. The characteristics of time-sharing system: simultaneity, independence, timeliness and interaction.

4. the requirements of the real-time system: be able to respond in time, have high reliability and security, and do not force the utilization of system resources.

5. Network operating system: combine the computers in the network organically to realize the communication and resource sharing among the computers.

Distributed OS: there is no primary or secondary distinction between computers in the network, any two computers exchange information through communication, and the resources in the network are shared by all users, which can enable several computers to cooperate to complete a common task and execute them in parallel on several computers.

6. The hardware system is composed of CPU, main memory, Imax O control system and various peripherals.

7. When CPU executes the program in the tube mode, it does not check the address of accessing the main memory, and only OS can modify the value of the base address register and the value of the limited length register.

8. The goal of operating system structure design: correctness, efficiency, maintainability and portability.

9. The methods of operating system structure design: disordered module method, kernel expansion method, hierarchical structure method, pipe program design method. The most important feature of the hierarchical structure method is to localize the whole problem.

10. Processor management is the core program of OS. A system call is a program executed in a tubular state.

11. The advantages of adopting multi-programming: improving the utilization rate of processors, making full use of peripherals, and giving full play to the parallel working ability between CPU and peripherals.

12. Processes are divided into user processes and system processes. The process that completes the OS function is called the system process.

13. PCB should contain four types of information: identification information, description information, on-site information and management information. (P34)

14. A process is created after assigning a workspace to a program and establishing a PCB. The initial state is ready.

15. PSW includes three parts: the basic state of the program, the interrupt code and the interrupt shield bit. Each program has a PSW.

16. Interrupt priority order: hardware failure interrupts, voluntary interrupts, procedural interrupts, external interrupts, input and output interrupts.

17. The selection principle of process scheduling algorithm: processor utilization, throughput, waiting time, response time.

18. The functions of storage management: space allocation and de-allocation, address translation, main memory space sharing and protection, space expansion.

19. Management of a partition: set a limit register in the processor, the content remains the same, and only one job can be loaded into the main memory.

20. Management of multiple fixed partitions: the number and size of partitions are fixed, which can be used for multiprogramming, and the processor sets two upper registers and limited registers.

21. Management of multiple variable partitions: commonly used allocation algorithms: first adaptation, optimal adaptation, worst adaptation (P60) processor sets two base address registers and limited length registers.

22. Page management: hardware support is needed. The block is the physical unit of the main memory space allocation. The address structure determines the size of the main memory block. Page tables are generally stored in main memory.

23. Segment management: each job can be divided into up to 2 ^ (mmurn) segments, and the maximum length of each segment can reach 2 ^ n bytes. Hardware support is required. Each segment occupies a contiguous area of memory.

In partition storage management and page management, the logical address of the user is contiguous. And the paragraph pattern is discontinuous.

25. The capacity of virtual memory is determined by the address structure of the computer.

26. The rate of missing pages = the number of missing pages / the total number of visits to the page. Segment-page virtual storage management is generally used only on mainframe computers.

27. Files are divided by purpose: system files, library files, user files, according to protection level: executive files, read-only files, read-write files.

28. Logical files can be divided into stream files and record files, and the physical structure is divided into sequential files, linked files and index files.

29. The physical unit of the storage medium is defined as the volume, the area of continuous information on the storage medium is the block, and the physical unit of information exchange.

Which access mode is used is related to how to use files and the characteristics of storage media.

31. What a file directory entry should contain: information about access control, information about file structure, and information about file management.

32. The advantages of tree directory: it solves the problem of duplicate names, is conducive to the classification of files, improves the speed of file retrieval, and can control access rights.

33. A logical record is the smallest unit of information that can be accessed independently in a file.

34. The biggest advantage of using sequential structure for sequential access files is that the access speed is fast.

35. The problems existing in the sequential structure: low utilization of disk storage space, difficult to estimate the number of disk blocks needed for output files, and influence expansion.

36. The work of combining several logical records into a block is called a group of records, and the number of records in each block is called a block factor.

37. There are two ways to connect free blocks: single block connection and group connection.

38. Ways to keep files secret: hide file directories, set passwords, and use passwords.

39. The number determined by the system for the equipment is an absolute number, and the equipment number defined by the user in the program is a relative number.

40. Block is the smallest unit for reading and writing information. Cylinders * (j+i*t) I: number of cylinders, J: number of heads, K: sectors, S: number of sectors on each disk. B: block number.

41. Disk drive scheduling consists of two parts: "moving arm scheduling" and "rotation scheduling".

42. The purpose of mobile arm scheduling is to input and output the search time as much as possible.

43. The shortest search time algorithm: select the request with the shortest search time from the waiting visitors and execute it first.

44. Elevator scheduling method: starting from the current position, select the visitor from the cylinder closest to the current mobile arm along the direction of the arm movement.

The input and output operation of transmitting information between the main memory and the peripheral equipment is completed by the channel.

46. The channel program is stored in the main memory, and the fixed unit used to store the first address of the channel is called the channel address word CAW.

47. SPOOL system consists of pre-input program, well management program and slow output program.

48. There are four states of operation in the input well: input status, reception status, execution status, and completion status.

49. there are two means of job processing steps: job control language and operation control command.

Job control methods are: batch processing mode, interactive mode. Batch processing is called offline mode, and interactive mode is also called online mode.

50. the user defines the source program, data and job control manual as files.

51. The principles of designing job scheduler algorithm: fairness, balanced use of resources, and great traffic.

52. Turnaround time = job end time-enter the "input well" time. Response ratio = waiting time / computing time

53. the operation interface provided by OS for users in interactive jobs: operation control command, menu technology, window technology.

54. Two characteristics of process sequencing: closeness and reproducibility. Concurrent processes with contacts must share some resources.

The uninterruptible process is called the primitive. A mailbox consists of a "mailbox description" and a "mailbox body".

56. PV operation and management are two typical synchronization mechanisms. There are two ways of process communication: direct communication and indirect communication.

57. The necessary conditions of deadlock: mutually exclusive use of resources, possession and waiting of resources, non-snatching of resources, circular waiting for resources.

58. Unix adopts a module structure centered on global variables, and the invocation relationship between modules is more complex.

59. The characteristics of Unix: short and short, concise and effective, easy to transplant, expandable and open.

60. Unix requires user programs to request system services with "trap instructions". The Shell command is the interface between the user and UNIX.

61. The system calls of Unix can be divided into file operation class, process control class, signal and time class.

62. The Unix system provides a pipeline mechanism to realize the information transmission between processes.

63. The composition of Unix process: process control block, text segment, data segment. The resident memory is called the basic control block, the proc structure.

64. A program that can be shared by multiple processes is called the body segment of a process, which is a reentrant program and consists of programs and constants.

65. Unix divides the data segment of the process into user stack area, user data area and system workspace.

66. The 0 process in Unix is also known as the swap process, and the task is to swap the process in or out. Execute the sched program to complete the work.

67. The Unix process goes to sleep because the request for resources is not met or waits for certain events, and becomes ready after waking up.

68. Processes always change from "running in a nuclear state of mind" to "sleeping in memory". It is done by sleep program.

69. Unix adopts dynamic priority number scheduling algorithm for process scheduling.

70. The file system of Unix is divided into basic file system and mountable sub-file system, including ordinary, directory and device files.

71. Devices are divided into block devices (disk, magnetic tape) and character devices (terminal, printer).

72. Unix uses buffering technology to realize the read and write operation of the device, and the device files are stored in the devsubdirectory under the root directory.

After reading the contents of the appeal, do you have a general understanding of the common operating system interview knowledge points? If you want to know more, welcome to follow the industry information channel!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.