如何用VC下的性能计数器获得CPU使用率

[rabbitweng]

用性能计数器（PDH）我已经能够得到诸如系统剩余内存值，但问题是，当我用\Processor(_Total)\% Idle Time 这个计数器想获得CPU空闲时间，从而得到cpu使用率时，发现每次都是一个非常接近0的值，这与在用系统的“任务管理器”时获得的值不太相同（试验了n次，每次都是接近0），而用\Processor(_Total)\% Processor Time计数器获得的值却总是相当接近1，何解？

另外，想获得cpu使用率该使用那个具体的计数器？

拜谢先！

[xx_jj]

关注

[taianmonkey]

// cpusagent.cpp (Windows NT/2000)
//
// Getting the CPU usage in percent on Windows NT/2000
//
// (c)2000 Ashot Oganesyan K, SmartLine, Inc
// mailto:[e-mail], http://www.protect-me.com, http://www.codepile.com

#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): ");
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("\b\b\b\b%3d%%",(UINT)dbIdleTime);
}

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

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

[wlzqi]

或者你找我 [e-mail]

[rabbitweng]

谢谢wlzqi(wlzqi)的回复
我的邮箱： [e-mail]
由于邮箱里垃圾邮件较多,最好标题注明:cpu使用率
谢谢!!

[rabbitweng]

感谢taianmonkey()的回复，但这种方法我似乎在网上看到的是不支持XP操作系统，而我的这个程序必须要能在2000/xp/2003下正常工作，所以是不是不太可行？

ps：
谁能告诉我用计数器获得cpu使用率的方法？
谢谢先！

[wlzqi]

流下Email。我给你发段代码

[taianmonkey]

xp下当然支持！这就是在xp下的代码！