linux c获取cpu占用率

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

void get_cpu_usage(double *user, double *system, double *idle) {
    FILE *fp;
    char buffer[1024];
    char line[128];
    long long user_jiffies, nice_jiffies, system_jiffies, idle_jiffies, iowait_jiffies, irq_jiffies, softirq_jiffies;

    fp = fopen("/proc/stat", "r");
    if (fp == NULL) {
        perror("Failed to open /proc/stat");
        return;
    }

    fgets(line, sizeof(line), fp);
    sscanf(line, "cpu %lld %lld %lld %lld %lld %lld %lld", &user_jiffies, &nice_jiffies, &system_jiffies, &idle_jiffies, &iowait_jiffies, &irq_jiffies, &softirq_jiffies);

    fclose(fp);

    static long long prev_user_jiffies = 0, prev_nice_jiffies = 0, prev_system_jiffies = 0, prev_idle_jiffies = 0;
    static int first_run = 1;

    if (first_run) {
        prev_user_jiffies = user_jiffies;
        prev_nice_jiffies = nice_jiffies;
        prev_system_jiffies = system_jiffies;
        prev_idle_jiffies = idle_jiffies;
        first_run = 0;
        return;
    }

    long long total_jiffies = user_jiffies + nice_jiffies + system_jiffies + idle_jiffies + iowait_jiffies + irq_jiffies + softirq_jiffies;
    long long prev_total_jiffies = prev_user_jiffies + prev_nice_jiffies + prev_system_jiffies + prev_idle_jiffies + iowait_jiffies + irq_jiffies + softirq_jiffies;

    *user = (double)(user_jiffies - prev_user_jiffies) / (total_jiffies - prev_total_jiffies) * 100;
    *system = (double)(system_jiffies - prev_system_jiffies) / (total_jiffies - prev_total_jiffies) * 100;
    *idle = (double)(idle_jiffies - prev_idle_jiffies) / (total_jiffies - prev_total_jiffies) * 100;

    prev_user_jiffies = user_jiffies;
    prev_nice_jiffies = nice_jiffies;
    prev_system_jiffies = system_jiffies;
    prev_idle_jiffies = idle_jiffies;
}

int main() {
    double user, system, idle;
    while (1) {
        get_cpu_usage(&user, &system, &idle);
        printf("User: %.2f%%, System: %.2f%%, Idle: %.2f%%\n", user, system, idle);
        sleep(1);
    }
    return 0;
}