vc编写cpu使用率

最新推荐文章于 2024-03-14 07:34:28 发布

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本文档介绍了作者在研究如何通过VC编写程序获取CPU使用率的过程和理解。核心在于理解CPU占用率的计算方式，即在特定时间段内消耗的CPU时间与总时间的比例。

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这几天研究如何获取cpu使用率，研究来研究去，根据别人的总结来写一篇自己的理解文档吧

#include <windows.h>
#include <conio.h>
#include <stdio.h>

#define SystemBasicInformation 0
#define SystemPerformanceInformation 2
#define SystemTimeInformation 3

#define Li2Double(x) ((double)((x).HighPart) * 4.294967296E9 + (double)((x).LowPart))

typedef struct
{
    DWORD dwUnknown1;
    ULONG uKeMaximumIncrement;
    ULONG uPageSize;
    ULONG uMmNumberOfPhysicalPages;
    ULONG uMmLowestPhysicalPage;
    ULONG uMmHighestPhysicalPage;
    ULONG uAllocationGranularity;
    PVOID pLowestUserAddress;
    PVOID pMmHighestUserAddress;
    ULONG uKeActiveProcessors;
    BYTE bKeNumberProcessors;
    BYTE bUnknown2;
    WORD wUnknown3;
} SYSTEM_BASIC_INFORMATION;

typedef struct
{
    LARGE_INTEGER liIdleTime;
    DWORD dwSpare[76];
} SYSTEM_PERFORMANCE_INFORMATION;

typedef struct
{
    LARGE_INTEGER liKeBootTime;
    LARGE_INTEGER liKeSystemTime;
    LARGE_INTEGER liExpTimeZoneBias;
    ULONG uCurrentTimeZoneId;
    DWORD dwReserved;
} SYSTEM_TIME_INFORMATION;


// ntdll!NtQuerySystemInformation (NT specific!)
//
// The function copies the system information of the
// specified type into a buffer
//
// NTSYSAPI
// NTSTATUS
// NTAPI
// NtQuerySystemInformation(
// IN UINT SystemInformationClass, // information type
// OUT PVOID SystemInformation, // pointer to buffer
// IN ULONG SystemInformationLength, // buffer size in bytes
// OUT PULONG ReturnLength OPTIONAL // pointer to a 32-bit
// // variable that receives
// // the number of bytes
// // written to the buffer
// );
typedef LONG (WINAPI *PROCNTQSI)(UINT,PVOID,ULONG,PULONG);

PROCNTQSI NtQuerySystemInformation;


void main(void)
{
    SYSTEM_PERFORMANCE_INFORMATION SysPerfInfo;
    SYSTEM_TIME_INFORMATION SysTimeInfo;
    SYSTEM_BASIC_INFORMATION SysBaseInfo;
    double dbIdleTime;
    double dbSystemTime;
    LONG status;
    LARGE_INTEGER liOldIdleTime = {0,0};
    LARGE_INTEGER liOldSystemTime = {0,0};

    NtQuerySystemInformation = (PROCNTQSI)GetProcAddress(GetModuleHandle("ntdll"),"NtQuerySystemInformation");

    if (!NtQuerySystemInformation)
        return;

    // get number of processors in the system
    status = NtQuerySystemInformation(SystemBasicInformation,&SysBaseInfo,sizeof(SysBaseInfo),NULL);
    if (status != NO_ERROR)
        return;

    printf("/nCPU Usage (press any key to exit) /n");
    while(!_kbhit())
    {
        // get new system time
        status = NtQuerySystemInformation(SystemTimeInformation,&SysTimeInfo,sizeof(SysTimeInfo),0);
        if (status!=NO_ERROR)
            return;

        // get new CPU's idle time
        status =NtQuerySystemInformation(SystemPerformanceInformation,&SysPerfInfo,sizeof(SysPerfInfo),NULL);
        if (status != NO_ERROR)
            return;

        // if it's a first call - skip it
        if (liOldIdleTime.QuadPart != 0)
        {
            // CurrentValue = NewValue - OldValue
            dbIdleTime = Li2Double(SysPerfInfo.liIdleTime) - Li2Double(liOldIdleTime);
            dbSystemTime = Li2Double(SysTimeInfo.liKeSystemTime) -

                Li2Double(liOldSystemTime);

            // CurrentCpuIdle = IdleTime / SystemTime
            dbIdleTime = dbIdleTime / dbSystemTime;

            // CurrentCpuUsage% = 100 - (CurrentCpuIdle * 100) / NumberOfProcessors
            dbIdleTime = 100.0 - dbIdleTime * 100.0 /

                (double)SysBaseInfo.bKeNumberProcessors + 0.5;

            printf("CPU Usage (press any key to exit) : %3d%% /n",(UINT)dbIdleTime);
        }

        // store new CPU's idle and system time
        liOldIdleTime = SysPerfInfo.liIdleTime;
        liOldSystemTime = SysTimeInfo.liKeSystemTime;

        // wait one second
        Sleep(1000);
    }
    printf("/n");
}

搜了很多的文档基本上都会告诉你这么写可以得到cpu使用率，但发现在win7下（我的系统）运行出错了，断点后你会发现执行

status =NtQuerySystemInformation(SystemPerformanceInformation,&SysPerfInfo,sizeof(SysPerfInfo),NULL);

出错，可能这些文章都是比较早的，那是流行的是xp or 更早的系统，可能在哪些系统下能得到cpu使用率吧

后来找到了以下

#define _WIN32_WINNT   0x0501
#include <Windows.h>
#include <iostream> 
using   namespace   std;

__int64 CompareFileTime ( FILETIME time1, FILETIME time2 )
{
       __int64 a = time1.dwHighDateTime << 32 | time1.dwLowDateTime ;
       __int64 b = time2.dwHighDateTime << 32 | time2.dwLowDateTime ;

       return   (b - a);
}
void main() 
{ 
HANDLE hEvent;
BOOL res ;

FILETIME preidleTime;
FILETIME prekernelTime;
FILETIME preuserTime;

FILETIME idleTime;
FILETIME kernelTime;
FILETIME userTime;

res = GetSystemTimes( &idleTime, &kernelTime, &userTime );

preidleTime = idleTime;
prekernelTime = kernelTime;
preuserTime = userTime ;

hEvent = CreateEvent (NULL,FALSE,FALSE,NULL); // 初始值为 nonsignaled ，并且每次触发后自动设置为nonsignaled

while (1){
      WaitForSingleObject( hEvent,1000 ); //等待500毫秒
      res = GetSystemTimes( &idleTime, &kernelTime, &userTime );
     
       int idle = CompareFileTime( preidleTime,idleTime);
       int kernel = CompareFileTime( prekernelTime, kernelTime);
       int user = CompareFileTime(preuserTime, userTime);

int cpu = (kernel +user - idle) *100/(kernel+user);
     int cpuidle = ( idle) *100/(kernel+user);
     cout << "CPU利用率:" << cpu << "%" << "      CPU空闲率:" <<cpuidle << "%" <<endl;
  

    preidleTime = idleTime;
    prekernelTime = kernelTime;
    preuserTime = userTime ;
    }
}

这个能再win7下获得cpu的使用率

方法都离不开一个概念就是cpu使用率的计算

CPU占用率：在一个时间段内消耗的CPU时间与该时间段长度的比值。