Performance counters CPU usage

http://msdn.microsoft.com/en-us/library/windows/desktop/aa373169(v=vs.85).aspx

#include <windows.h>#include <stdio.h>#include <pdh.h>#include <pdhmsg.h>#pragma comment(lib, "pdh.lib")CONST PWSTR COUNTER_PATH    = L"\\Processor(0)\\% Processor Time";void DisplayCommandLineHelp(void){    wprintf(L"The command line must contain a valid log file name.\n");}void wmain(int argc, WCHAR **argv){    HQUERY hQuery = NULL;    HCOUNTER hCounter = NULL;    PDH_STATUS status = ERROR_SUCCESS;    DWORD dwFormat = PDH_FMT_DOUBLE;     PDH_FMT_COUNTERVALUE ItemBuffer;    if (argc != 2)     {        DisplayCommandLineHelp();        goto cleanup;    }    // Opens the log file that Writein Performance Data to a Log File     // example created.    status = PdhOpenQuery(argv[1], 0, &hQuery);    if (ERROR_SUCCESS != status)    {        wprintf(L"PdhOpenQuery failed with 0x%x\n", status);        goto cleanup;    }       // Add the same counter used when writing the log file.    status = PdhAddCounter(hQuery, COUNTER_PATH, 0, &hCounter);       if (ERROR_SUCCESS != status)    {        wprintf(L"PdhAddCounter failed with 0x%x\n", status);        goto cleanup;    }    // Read a performance data record.    status = PdhCollectQueryData(hQuery);    if (ERROR_SUCCESS != status)    {        wprintf(L"PdhCollectQueryData failed with 0x%x\n", status);        goto cleanup;    }    while (ERROR_SUCCESS == status)     {         // Read the next record        status = PdhCollectQueryData(hQuery);        if (ERROR_SUCCESS == status)        {            // Format the performance data record.            status = PdhGetFormattedCounterValue(hCounter,                dwFormat,                (LPDWORD)NULL,                &ItemBuffer);            if (ERROR_SUCCESS != status)            {                wprintf(L"PdhGetFormattedCounterValue failed with 0x%x.\n", status);                goto cleanup;            }            wprintf(L"Formatted counter value = %.20g\n", ItemBuffer.doubleValue);        }        else        {            if (PDH_NO_MORE_DATA != status)            {                wprintf(L"PdhCollectQueryData failed with 0x%x\n", status);            }        }    }cleanup:    // Close the query.    if (hQuery)        PdhCloseQuery(hQuery);}