如何实时获取系统每个进程占用的CPU

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　　本文的目的是为了和大家讨论一个问题，同时给出一个根据进程ID，来返回该进程实时占用的CPU使用率的函数。希望大家在用这个函数的时候别忘记我的问题。

　　目前计算进程CPU占用率的方法主要有两种，一种是根据时间来计算，另一种根据注册表计算，我使用的是前者。前者方法原理：在一个特定时间段内计算特定进程的总时间和所有进程的总时间，它们的比值就是那个特定进程的确CPU占有率。

　　我写了一个函数(改写)，以进程的ID作为参数，进程CPU占用率作为返回值，实时计算特定进程的CPU占用，测试正确。整个程序如下：

　　结构定义：

typedef struct _THREAD_INFO
{
LARGE_INTEGER CreateTime;
DWORD dwUnknown1;
DWORD dwStartAddress;
DWORD StartEIP;
DWORD dwOwnerPID;
DWORD dwThreadId;
DWORD dwCurrentPriority;
DWORD dwBasePriority;
DWORD dwContextSwitches;
DWORD Unknown;
DWORD WaitReason;
}THREADINFO, *PTHREADINFO;
typedef struct _UNICODE_STRING
{
 USHORT Length;
 USHORT MaxLength;
 PWSTR Buffer;
} UNICODE_STRING;
typedef struct _PROCESS_INFO
{
DWORD dwOffset;
DWORD dwThreadsCount;
DWORD dwUnused1[6];
LARGE_INTEGER CreateTime;
LARGE_INTEGER UserTime;
LARGE_INTEGER KernelTime;
UNICODE_STRING ProcessName;
DWORD dwBasePriority;
DWORD dwProcessID;
DWORD dwParentProcessId;
DWORD dwHandleCount;
DWORD dwUnused3[2];
DWORD dwVirtualBytesPeak;
DWORD dwVirtualBytes;
ULONG dwPageFaults;
DWORD dwWorkingSetPeak;
DWORD dwWorkingSet;
DWORD dwQuotaPeakPagedPoolUsage;
DWORD dwQuotaPagedPoolUsage;
DWORD dwQuotaPeakNonPagedPoolUsage;
DWORD dwQuotaNonPagedPoolUsage;
DWORD dwPageFileUsage;
DWORD dwPageFileUsagePeak;
DWORD dCommitCharge;
THREADINFO ThreadSysInfo[1];
} PROCESSINFO, *PPROCESSINFO;

　　函数定义：

int Button2Click(int id);//参数是进程ID
函数实体：
int Button2Click(int id)
{
int cpuusage;
PVOID pProcInfo = NULL;
DWORD dwInfoSize = 0x20000;
PPROCESSINFO pProcessInfo;
DWORD dwWorkingSet;
long ( __stdcall *NtQuerySystemInformation )( DWORD, PVOID, DWORD, DWORD );

static __int64 LastTotalProcessCPUUsage = 0;
static __int64 LastCurrentProcessCPUUsage = 0;
int CurrentDelta;
int TotalDelta;
__int64 TotalProcessCPUUsage = 0;
__int64 CurrentProcessCPUUsage = 0;
/////////////////////////////////
pProcInfo = (PVOID)(new byte[dwInfoSize]);
NtQuerySystemInformation = (long(__stdcall*)(DWORD,PVOID,DWORD,DWORD))
GetProcAddress( GetModuleHandle( "ntdll.dll" ),"NtQuerySystemInformation" );
NtQuerySystemInformation(5,pProcInfo,dwInfoSize,0);
pProcessInfo = (PPROCESSINFO)pProcInfo;
do
{
TotalProcessCPUUsage += (__int64)pProcessInfo-KernelTime.QuadPart + (__int64)pProcessInfo-UserTime.QuadPart;
if(pProcessInfo-dwProcessID == id)
{
dwWorkingSet = pProcessInfo-dwWorkingSet;
CurrentProcessCPUUsage += (__int64)pProcessInfo-KernelTime.QuadPart + (__int64)pProcessInfo-UserTime.QuadPart;
}
/////////
if(pProcessInfo-dwOffset == 0)
{
break;
}
pProcessInfo = (PPROCESSINFO)((byte*)pProcessInfo + pProcessInfo-dwOffset);
}
while(true);
TotalDelta = TotalProcessCPUUsage - LastTotalProcessCPUUsage;
CurrentDelta = CurrentProcessCPUUsage - LastCurrentProcessCPUUsage;
if(TotalDelta != 0)
cpuusage = 100 * CurrentDelta / TotalDelta;
//this-Caption = "CPU = " + IntToStr(100 * CurrentDelta / TotalDelta) +
//"Memory = "+ IntToStr(dwWorkingSet / 1024) " K";
LastTotalProcessCPUUsage = TotalProcessCPUUsage;
LastCurrentProcessCPUUsage = CurrentProcessCPUUsage;
delete[] pProcInfo;
return cpuusage;
}

　　控制台调用：

int main(void)
{
 while(true)
 {
　int s = Button2Click(0);//在此把进程ID作为参数传入
　printf("%dn",s);
　Sleep(1000);
 }
 return 0;
}

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　　以上代码运行非常正常

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