使用c语言获取linux系统各个CPU核心的使用率

要获取Linux系统各个CPU核心的使用率，可以使用C语言编写程序，通过读取/proc/stat文件中的信息来获取。

下面是一个简单的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define MAX_CPU_NUM 8   // 假设最多有8个CPU核心

int main() {
    int i;
    long int user1, nice1, sys1, idle1, iowait1, irq1, softirq1, steal1, guest1, guest_nice1;
    long int user2, nice2, sys2, idle2, iowait2, irq2, softirq2, steal2, guest2, guest_nice2;
    double usage[MAX_CPU_NUM];

    while (1) {
        // 读取/proc/stat文件，获取CPU的使用情况
        FILE* fp = fopen("/proc/stat", "r");
        if (fp == NULL) {
            perror("fopen");
            exit(1);
        }
        fscanf(fp, "cpu %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld\n", 
            &user1, &nice1, &sys1, &idle1, &iowait1, &irq1, &softirq1, &steal1, &guest1, &guest_nice1);
        fclose(fp);

        // 等待一段时间，再次读取/proc/stat文件，获取CPU的使用情况
        sleep(1);
        fp = fopen("/proc/stat", "r");
        if (fp == NULL) {
            perror("fopen");
            exit(1);
        }
        fscanf(fp, "cpu %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld\n", 
            &user2, &nice2, &sys2, &idle2, &iowait2, &irq2, &softirq2, &steal2, &guest2, &guest_nice2);
        fclose(fp);

        // 计算每个CPU核心的使用率
        for (i = 0; i < MAX_CPU_NUM; i++) {
            double total1 = user1 + nice1 + sys1 + idle1 + iowait1 + irq1 + softirq1 + steal1 + guest1 + guest_nice1;
            double total2 = user2 + nice2 + sys2 + idle2 + iowait2 + irq2 + softirq2 + steal2 + guest2 + guest_nice2;
            double idle_delta = idle2 - idle1;
            double total_delta = total2 - total1;
            usage[i] = 100.0 * (1.0 - idle_delta / total_delta);
            user1 = user2;
            nice1 = nice2;
            sys1 = sys2;
            idle1 = idle2;
            iowait1 = iowait2;
            irq1 = irq2;
            softirq1 = softirq2;
            steal1 = steal2;
            guest1 = guest2;
            guest_nice1 = guest_nice2;
        }

        // 输出每个CPU核心的使用率
        for (i = 0; i < MAX_CPU_NUM; i++) {
            printf("CPU%d usage: %.2f%%\n", i, usage[i]);
        }
        printf("\n");
    }

    return 0;
}

这个程序会不断循环读取/proc/stat文件，计算每个CPU核心的使用率，并输出结果。注意，程序中假设最多有8个CPU核心，如果实际系统中CPU核心数不足8个，可以根据实际情况修改代码。