一、功能介绍
通过读取/proc/stat文件获取当前系统的CPU占用率。
Linux系统上的/proc目录是一种文件系统，即proc文件系统，与其它常见的文件系统不同的是，/proc文件系统是一个伪文件系统，它只存在内存当中，而不占用外存空间。它以文件系统的方式为内核与进程提供通信的接口。用户和应用程序可以通过/proc得到系统的信息，并可以改变内核的某些参数。由于系统的信息，如进程，是动态改变的，所以用户或应用程序读取/proc目录中的文件时，proc文件系统是动态从系统内核读出所需信息并提交的。
/proc/stat文件包含了所有CPU活动的信息，该文件中的所有值都是从系统启动开始累计到当前时刻。不同内核版本中该文件的格式可能不大一致。
wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c$ cat /proc/stat cpu 673896 219583 260680 4878312 1821 0 4364 0 0 0 cpu0 320077 75898 124098 2490890 1231 0 2451 0 0 0 cpu1 353819 143684 136582 2387421 589 0 1913 0 0 0 intr 16591367 3 19561 0 0 0 0 0 0 1 0 0 0 1033239 0 0 0 360062 318044 40 343791 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1154266 0 0 15434 5315 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ctxt 28277855 btime 1598774265 processes 117139 procs_running 1 procs_blocked 0 softirq 9953753 74 4098860 4860 347201 336159 0 26182 2177955 0 2962462 wbyq@wbyq:/mnt/hgfs/linux-share-dir/linux_c$
二、代码实现
#include <stdio.h> #include <stdlib.h> #include <unistd.h> typedef struct cpu_occupy_ //定义一个cpu occupy的结构体 { char name[20]; //定义一个char类型的数组名name有20个元素 unsigned int user; //定义一个无符号的int类型的user unsigned int nice; //定义一个无符号的int类型的nice unsigned int system; //定义一个无符号的int类型的system unsigned int idle; //定义一个无符号的int类型的idle unsigned int iowait; unsigned int irq; unsigned int softirq; }cpu_occupy_t; double cal_cpuoccupy (cpu_occupy_t *o, cpu_occupy_t *n) { double od, nd; double id, sd; double cpu_use ; od = (double) (o->user + o->nice + o->system +o->idle+o->softirq+o->iowait+o->irq);//第一次(用户+优先级+系统+空闲)的时间再赋给od nd = (double) (n->user + n->nice + n->system +n->idle+n->softirq+n->iowait+n->irq);//第二次(用户+优先级+系统+空闲)的时间再赋给od id = (double) (n->idle); //用户第一次和第二次的时间之差再赋给id sd = (double) (o->idle) ; //系统第一次和第二次的时间之差再赋给sd if((nd-od) != 0) cpu_use =100.0 - ((id-sd))/(nd-od)*100.00; //((用户+系统)乖100)除(第一次和第二次的时间差)再赋给g_cpu_used else cpu_use = 0; return cpu_use; } void get_cpuoccupy (cpu_occupy_t *cpust) { FILE *fd; int n; char buff[256]; cpu_occupy_t *cpu_occupy; cpu_occupy=cpust; fd = fopen ("/proc/stat", "r"); if(fd == NULL) { perror("fopen:"); exit (0); } fgets (buff, sizeof(buff), fd); sscanf (buff, "%s %u %u %u %u %u %u %u", cpu_occupy->name, &cpu_occupy->user, &cpu_occupy->nice,&cpu_occupy->system, &cpu_occupy->idle ,&cpu_occupy->iowait,&cpu_occupy->irq,&cpu_occupy->softirq); fclose(fd); } double get_sysCpuUsage() { cpu_occupy_t cpu_stat1; cpu_occupy_t cpu_stat2; double cpu; get_cpuoccupy((cpu_occupy_t *)&cpu_stat1); sleep(1); //第二次获取cpu使用情况 get_cpuoccupy((cpu_occupy_t *)&cpu_stat2); //计算cpu使用率 cpu = cal_cpuoccupy ((cpu_occupy_t *)&cpu_stat1, (cpu_occupy_t *)&cpu_stat2); return cpu; } int main(int argc,char **argv) { while(1) { printf("CPU占用率:%f\n",get_sysCpuUsage()); } return 0; }
三、ubuntu18.04下运行效果
四、redhat6.3系统上运行效果
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