某个正在运行的程序的CPU占用率

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;

//每秒钟查询一次
void __fastcall TForm1::Timer1Timer(TObject *Sender)
{
Button2Click(NULL);
}
//---------------------------------------------------------------------------

void __fastcall TForm1::Button2Click(TObject *Sender)
{
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 == GetCurrentProcessId())
{
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)
this->Caption = "CPU = " + IntToStr(100 * CurrentDelta / TotalDelta) +
"Memory = "+ IntToStr(dwWorkingSet / 1024) " K";

LastTotalProcessCPUUsage = TotalProcessCPUUsage;
LastCurrentProcessCPUUsage = CurrentProcessCPUUsage;

delete[] pProcInfo;
}

不知道你找到的是不是这个代码。这个程序是查寻自身CPU占用的，但其实他有能力查询所有的程序，请注意if(pProcessInfo->dwProcessID == GetCurrentProcessId())这个地方。
要说CPU占用率，其实就是NtQuerySystemInformation查询，没什么关键的地方。