MFC如何获取系统CPU使用率API

1、通过查阅msdn，可以知道GetSystemTimes函数可以获取系统的时间，可以获得系统（自开机以来)处于Kernel状态下面的CPU时间,以及系统处于User状态下的时间,以及Idle的时间.我们只用Kernel时间和User时间, 不用Idle时间.

2、通过计算公式来计算（总的时间-空闲时间）/总的时间=占用cpu的时间就是使用率这个应该容易理解，利用率就是有效的使用时间在全部时间中的占比

3、简单写个demo测试下，代码如下#include <stdio.h> #include <Windows.h> #include <time.h> #include <tchar.h>__int64 DiffFileTime(FILETIME time1, FILETIME time2){__int64 a = time1.dwHighDateTime << 32 | time1.dwLowDateTime;__int64 b = time2.dwHighDateTime << 32 | time2.dwLowDateTime;return b - a;}int main(int argc, char* argv[]){double cpuuse;int idle, kernel, user;FILETIME idleTime1, idleTime2;FILETIME kernelTime1, kernelTime2;FILETIME userTime1, userTime2;do{GetSystemTimes(&idleTime1, &kernelTime1, &userTime1);Sleep(1000);GetSystemTimes(&idleTime2, &kernelTime2, &userTime2);idle = (int)DiffFileTime(idleTime1, idleTime2);kernel = (int)DiffFileTime(kernelTime1, kernelTime2);user = (int)DiffFileTime(userTime1, userTime2);if (kernel + user == 0)cpuuse = 0.0;elsecpuuse = abs((kernel + user - idle) * 100 / (kernel + user));//（总的时间-空闲时间）/总的时间=占用cpu的时间就是使用率printf("cpu useage: %01f!\n", cpuuse);} while (1);return 0;}

4、运行程序，对比任务管理器的cpu使用率，发现是一样的，可以参考以上代码把这功能代码封装成一个功能函数，方便调用

5、接下来，进一步对代码进行优化，将获取cpu的封装成一个通用的接口,优化后代码如下#include <stdio.h> #include <Windows.h> #include <time.h> #include <tchar.h>__int64 DiffFileTime(FILETIME time1, FILETIME time2){ __int64 a = time1.dwHighDateTime << 32 | time1.dwLowDateTime; __int64 b = time2.dwHighDateTime << 32 | time2.dwLowDateTime; return b - a;}double GetCpuUsage(){ double cpuuse; int idle, kernel, user; FILETIME idleTime1, idleTime2; FILETIME kernelTime1, kernelTime2; FILETIME userTime1, userTime2; GetSystemTimes(&idleTime1, &kernelTime1, &userTime1); Sleep(1000); GetSystemTimes(&idleTime2, &kernelTime2, &userTime2); idle = (int)DiffFileTime(idleTime1, idleTime2); kernel = (int)DiffFileTime(kernelTime1, kernelTime2); user = (int)DiffFileTime(userTime1, userTime2); if (kernel + user == 0) cpuuse = 0.0; else cpuuse = abs((kernel + user - idle) * 100 / (kernel + user));//（总的时间-空闲时间）/总的时间=占用cpu的时间就是使用率 return cpuuse;}int main(int argc, char* argv[]){ double cpuusage = 0; do { cpuusage = GetCpuUsage(); printf("cpu useage: %01f!\n", cpuuse); } while (1); return 0;}

6、上面的写法其实还有一个缺点，就是获取的时候需要延时一秒，这个对直接调用不太好，可以使用线程或者定时器和加锁保护读写同步来代替，参考代码如下#include <stdio.h> #include <Windows.h> #include <time.h> #include <tchar.h>__int64 DiffFileTime(FILETIME time1, FILETIME time2){ __int64 a = time1.dwHighDateTime << 32 | time1.dwLowDateTime; __int64 b = time2.dwHighDateTime << 32 | time2.dwLowDateTime; return b - a;}CRITICAL_SECTION slock;double scpuuse = 0;void SetCpuUsage(double cpu){ EnterCriticalSection(&slock); scpuuse = cpu; LeaveCriticalSection(&slock);}double GetCpuUsage(){ double cpu = 0; EnterCriticalSection(&slock); cpu = scpuuse; LeaveCriticalSection(&slock); return cpu;}DWORD WINAPI ThreadProc(LPVOID lpParam){ int idle, kernel, user; FILETIME idleTime1, idleTime2; FILETIME kernelTime1, kernelTime2; FILETIME userTime1, userTime2; do { GetSystemTimes(&idleTime1, &kernelTime1, &userTime1); Sleep(1000); GetSystemTimes(&idleTime2, &kernelTime2, &userTime2); idle = (int)DiffFileTime(idleTime1, idleTime2); kernel = (int)DiffFileTime(kernelTime1, kernelTime2); user = (int)DiffFileTime(userTime1, userTime2); if (kernel + user == 0) SetCpuUsage(0.0); else SetCpuUsage(abs((kernel + user - idle) * 100 / (kernel + user)));//（总的时间-空闲时间）/总的时间=占用cpu的时间就是使用率 } while (1);}int main(int argc, char* argv[]){ HANDLE m_hThread; InitializeCriticalSection(&slock); m_hThread = CreateThread(NULL, 0, ThreadProc, 0, 0, NULL);//创建新线程 do { printf("cpu useage: %01f!\n", GetCpuUsage()); Sleep(1000); } while (1); CloseHandle(m_hThread); DeleteCriticalSection(&slock); return 0;}