foreword
Hello everyone, welcome to the YY drop Linux series, a warm welcome! The main content of this chapter is aimed at veterans who have been in touch with Linux, and introduces the process from the operating system level:
the main content includes:
Welcome to subscribe to the YY drop Linux column! More dry goods are continuously updated! The following is the portal!
| Subscribe to the column reading: YY 's "Linux" series❀❀❀❀❀ |
|---|
| 【Linux Series-P1】Building a Linux Environment |
| [Linux Series-P2] Basic knowledge and instructions of Linux |
| 【Linux Series-P3】Linux Permissions |
| [Linux series-P4] Linux basic tools [yum] [vim] |
Article directory
1. The basic concept of process
- Textbook concepts: an execution instance of a program, a program being executed, etc.
- Kernel point of view: Acts as the entity that allocates system resources (CPU time, memory).
2. Describe the process-PCB
- Process information is placed in a data structure called a process control block, which can be understood as a collection of process attributes.
- The textbook is called PCB (process control block), and the PCB under the Linux operating system is: task_struct
A type of task_struct-PCB
- The structure describing the process in Linux is called task_struct.
- task_struct is a data structure of the Linux kernel that is loaded into RAM (memory) and contains process information.
task_ struct content classification
- Identifier: Describe the unique identifier of this process, which is used to distinguish other processes.
- Status: Task status, exit code, exit signal, etc.
- Priority: Priority relative to other processes.
- Program Counter: The address of the next instruction in the program to be executed.
- Memory pointers: including pointers to program code and process-related data, as well as pointers to memory blocks shared with other processes
- Context data: The data in the registers of the processor when the process is executed [example of suspension of studies, to add pictures of CPU, registers].
- I/O status information: including displayed I/O requests, I/O devices assigned to the process and a list of files used by the process.
- Billing information: May include sum of processor time, sum of clocks used, time limits, billing account number, etc.
- other information
4. "Organizational Process"
- It can be found in the kernel source code. All processes running in the system are stored in the kernel in the form of task_struct linked list .
5. "View process"
Operation 1: View process information
Process information can be viewed through the /proc system folder
- For example: To obtain the process information with PID 1, you need to view the /proc/1 folder.
Operation 2: Use user-level tools such as top and ps to obtain process information
- first create a process
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main()
{
while(1){
sleep(1);
}
return 0;
}
- After filtering with grep pipeline:
