CPU使用率计算

int CTestCPUDlg::CPUUsage(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; }

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;