Deep understanding of process priority in Linux

In-depth understanding of process priority in Linux requires specific code examples

In Linux systems, process priority is a very important concept. By properly setting the priority of the process, you can effectively control the allocation of system resources and improve system performance. This article will delve into the concept of process priority in Linux and demonstrate and practice it through specific code examples.

1. The concept of process priority in Linux

In the Linux system, the priority range of a process is -20 to 19, where -20 represents the highest priority and 19 represents the lowest priority . By default, all processes have priority 0. The priority of a process determines the size of the CPU time slice it gets in the system. Processes with higher priorities will get relatively more CPU time.

The Linux kernel uses a scheduling algorithm to decide which process gets CPU time, and can dynamically adjust the priority of the process based on system load and performance requirements. The priority of the process can be set by the nice value. The lower the nice value, the higher the priority, and vice versa.

2. Specific setting and acquisition of process priority

In the Linux system, you can use the nice command to set the priority of the process. For example, you can set the nice value of the process to -10 through the following command:

$ nice -n -10 ./my_program

At this time, the priority of the process my_program will be increased and more CPU time will be obtained. In addition to passing the nice command, you can also use the system call sched_setscheduler to set the scheduling policy and priority of the process.

In C language, you can use the sched_setscheduler system call to set the scheduling parameters of the process. The specific code is as follows:

#include <stdio.h>
#include <sched.h>

int main() {
    struct sched_param param;
    param.sched_priority = 10; // 设置进程的优先级为10

    if(sched_setscheduler(0, SCHED_FIFO, &param) < 0) {
        perror("sched_setscheduler");
        return -1;
    }

    while(1) {
        // 进程执行的代码
    }

    return 0;
}

This program sets the scheduling policy of the process to SCHED_FIFO by calling the sched_setscheduler function. (first in, first out) and set the priority to 10. In this example, the program will execute an infinite loop until manually terminated.

Through the above code examples, we can understand how to set the priority of the Linux process in C language, and further understand the impact of process priority on system performance. Properly setting the priority of the process is very important to improve the performance and response speed of the system.

3. Summary

In the Linux system, the priority of a process is an important concept that can be set through the nice value. It determines how much CPU time the process gets in the system. By setting appropriate priorities, you can effectively control the allocation of system resources and improve system performance.

Through the introduction and code examples of this article, I hope readers can have an in-depth understanding of process priorities in Linux and be able to flexibly set process priorities according to actual needs to achieve the best system performance and response speed.

Reference:

• Linux man pages
• Linux Advanced Programming by Mark Mitchell, Jeffrey Oldham, and Alex Samuel

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