Process of the operating system Chapter 1

1. The advent of the process has allowed us to separate the processes from the storage, with the memory management, and the process scheduling that requires different processes to move forward methodically.

2. Why should there be a process? What is a process?

In order to implement concurrent execution of the program, we invented the process. When a program is loaded into memory, it becomes a process.

3. Note that not all processes must be terminated, in fact, many system processes will not end unless the computer is forced to terminate or shut down.

4. What time does the process occur?

1) System initialization: In the initialization of a system, there will be many processes generated, the resulting processes are essential to the normal operation of the system.

2) Execution Process creation program: If you double-click an executable file.

3) User request to create a new process: The user's program through the system call directly generated a new process.

5. What time does the process die?

1) Sanitization: Exit when the process is finished running.

2) Suicide: The process exits itself due to an error.

3) Kill: The process is terminated by another process.

4) Execution: The process is forced to terminate as a result of an exception.

6. What causes the process to hang?

1) A process that performs some kind of blocking operation, such as reading and writing to a disk, hangs the process because the blocking operation waits for the result to continue execution.

2) Process execution time is too long, in order to be fair, the system suspends it.

7.3 typical states of the process, 4 conversions?

8. What information does the operating system record for the process?

The most basic information that the operating system records for a process is the process table and the Process Control block (BLOCKPCB). Different operating system maintenance process data is not the same, but basically includes register, program counter, status Word, stack pointer, priority, process ID, signal, Creation time, CPU time consumed, etc. The data structure adopted is mainly linear table, linked list and structure, tree and graph structure.

9. The root cause of the most problematic process management is the optimal allocation of resources.

10. Overview of CPU efficiency during multi-process

11. Sub-process

12. Deficiencies in the process?

1) It can only do one thing at a time, if you want to do two or more things at once, the process is not enough.

2) The process is suspended during execution, such as waiting for input, so that some work in the process is not dependent on the input data and cannot be pushed forward.

In order to solve these two problems, people invented the thread.

Process of the operating system Chapter 1