Calcolo dei valori dei contatori

La maggior parte dei tipi di contatori usa una formula per calcolare un valore visualizzabile per il contatore. Per un elenco dei tipi di contatori e delle relative formule, vedere la sezione Tipi di contatore di Windows Server 2003 Deployment Kit. Se il contatore richiede due campioni per calcolare il valore visualizzabile, viene impostato il flag del tipo di PERF_DELTA_COUNTER contatore.

Nell'esempio seguente viene illustrato come utilizzare i dati non elaborati per calcolare un valore visualizzabile per ogni tipo di contatore. Questo esempio si basa sull'esempio in Recupero dei dati contatori.

// Contains the elements required to calculate a counter value.
typedef struct
{
    DWORD CounterType;
    DWORD MultiCounterData;  // Second raw counter value for multi-valued counters
    ULONGLONG Data;          // Raw counter data
    LONGLONG Time;           // Is a time value or a base value
    LONGLONG Frequency;
} RAW_DATA;

// Use the CounterType to determine how to calculate the displayable
// value. The case statement includes the formula used to calculate
// the value.
BOOL DisplayCalculatedValue(RAW_DATA* pSample0, RAW_DATA* pSample1)
{
    BOOL fSuccess = TRUE;
    ULONGLONG numerator = 0;
    LONGLONG denominator = 0;
    double doubleValue = 0;
    DWORD dwordValue = 0;

    if (NULL == pSample1)
    {
        // Return error if the counter type requires two samples to calculate the value.
        switch (pSample0->CounterType)
        {
        default:
            if (PERF_DELTA_COUNTER != (pSample0->CounterType & PERF_DELTA_COUNTER))
            {
                break;
            }
            __fallthrough;
        case PERF_AVERAGE_TIMER: // Special case.
        case PERF_AVERAGE_BULK:  // Special case.
            wprintf(L"The counter type requires two samples but only one sample was provided.\n");
            fSuccess = FALSE;
            goto cleanup;
        }
    }
    else
    {
        if (pSample0->CounterType != pSample1->CounterType)
        {
            wprintf(L"The samples have inconsistent counter types.\n");
            fSuccess = FALSE;
            goto cleanup;
        }

        // Check for integer overflow or bad data from provider (the data from
        // sample 2 must be greater than the data from sample 1).
        if (pSample0->Data > pSample1->Data)
        {
            // Can happen for various reasons. Commonly occurs with the Process counterset when
            // multiple processes have the same name and one of them starts or stops.
            // Normally you'll just drop the older sample and continue.
            wprintf(L"Sample0 (%llu) is larger than sample1 (%llu).\n", pSample0->Data, pSample1->Data);
            fSuccess = FALSE;
            goto cleanup;
        }
    }

    switch (pSample0->CounterType)
    {
    case PERF_COUNTER_COUNTER:
    case PERF_SAMPLE_COUNTER:
    case PERF_COUNTER_BULK_COUNT:
        // (N1 - N0) / ((D1 - D0) / F)
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        dwordValue = (DWORD)(numerator / ((double)denominator / pSample1->Frequency));
        wprintf(L"Display value is: %lu%ls\n", dwordValue,
            (pSample0->CounterType == PERF_SAMPLE_COUNTER) ? L"" : L"/sec");
        break;

    case PERF_COUNTER_QUEUELEN_TYPE:
    case PERF_COUNTER_100NS_QUEUELEN_TYPE:
    case PERF_COUNTER_OBJ_TIME_QUEUELEN_TYPE:
    case PERF_COUNTER_LARGE_QUEUELEN_TYPE:
    case PERF_AVERAGE_BULK:  // normally not displayed
        // (N1 - N0) / (D1 - D0)
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        doubleValue = (double)numerator / denominator;
        if (pSample0->CounterType != PERF_AVERAGE_BULK)
            wprintf(L"Display value is: %f\n", doubleValue);
        break;

    case PERF_OBJ_TIME_TIMER:
    case PERF_COUNTER_TIMER:
    case PERF_100NSEC_TIMER:
    case PERF_PRECISION_SYSTEM_TIMER:
    case PERF_PRECISION_100NS_TIMER:
    case PERF_PRECISION_OBJECT_TIMER:
    case PERF_SAMPLE_FRACTION:
        // 100 * (N1 - N0) / (D1 - D0)
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        doubleValue = (double)(100 * numerator) / denominator;
        wprintf(L"Display value is: %f%%\n", doubleValue);
        break;

    case PERF_COUNTER_TIMER_INV:
        // 100 * (1 - ((N1 - N0) / (D1 - D0)))
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        doubleValue = 100 * (1 - ((double)numerator / denominator));
        wprintf(L"Display value is: %f%%\n", doubleValue);
        break;

    case PERF_100NSEC_TIMER_INV:
        // 100 * (1- (N1 - N0) / (D1 - D0))
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        doubleValue = 100 * (1 - (double)numerator / denominator);
        wprintf(L"Display value is: %f%%\n", doubleValue);
        break;

    case PERF_COUNTER_MULTI_TIMER:
        // 100 * ((N1 - N0) / ((D1 - D0) / TB)) / B1
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        denominator /= pSample1->Frequency;
        doubleValue = 100 * ((double)numerator / denominator) / pSample1->MultiCounterData;
        wprintf(L"Display value is: %f%%\n", doubleValue);
        break;

    case PERF_100NSEC_MULTI_TIMER:
        // 100 * ((N1 - N0) / (D1 - D0)) / B1
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        doubleValue = 100 * ((double)numerator / denominator) / pSample1->MultiCounterData;
        wprintf(L"Display value is: %f%%\n", doubleValue);
        break;

    case PERF_COUNTER_MULTI_TIMER_INV:
    case PERF_100NSEC_MULTI_TIMER_INV:
        // 100 * (B1 - ((N1 - N0) / (D1 - D0)))
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        doubleValue = 100 * (pSample1->MultiCounterData - ((double)numerator / denominator));
        wprintf(L"Display value is: %f%%\n", doubleValue);
        break;

    case PERF_COUNTER_RAWCOUNT:
    case PERF_COUNTER_LARGE_RAWCOUNT:
        // N as decimal
        wprintf(L"Display value is: %llu\n", pSample0->Data);
        break;

    case PERF_COUNTER_RAWCOUNT_HEX:
    case PERF_COUNTER_LARGE_RAWCOUNT_HEX:
        // N as hexadecimal
        wprintf(L"Display value is: 0x%llx\n", pSample0->Data);
        break;

    case PERF_COUNTER_DELTA:
    case PERF_COUNTER_LARGE_DELTA:
        // N1 - N0
        wprintf(L"Display value is: %llu\n", pSample1->Data - pSample0->Data);
        break;

    case PERF_RAW_FRACTION:
    case PERF_LARGE_RAW_FRACTION:
        // 100 * N / B
        doubleValue = (double)100 * pSample0->Data / pSample0->Time;
        wprintf(L"Display value is: %f%%\n", doubleValue);
        break;

    case PERF_AVERAGE_TIMER:
        // ((N1 - N0) / TB) / (B1 - B0)
        numerator = pSample1->Data - pSample0->Data;
        denominator = pSample1->Time - pSample0->Time;
        doubleValue = (double)numerator / pSample1->Frequency / denominator;
        wprintf(L"Display value is: %f seconds\n", doubleValue);
        break;

    case PERF_ELAPSED_TIME:
        // (D0 - N0) / F
        doubleValue = (double)(pSample0->Time - pSample0->Data) / pSample0->Frequency;
        wprintf(L"Display value is: %f seconds\n", doubleValue);
        break;

    case PERF_COUNTER_TEXT:
    case PERF_SAMPLE_BASE:
    case PERF_AVERAGE_BASE:
    case PERF_COUNTER_MULTI_BASE:
    case PERF_RAW_BASE:
    case PERF_COUNTER_NODATA:
    case PERF_PRECISION_TIMESTAMP:
        wprintf(L"Non-printing counter type.\n");
        break;

    default:
        wprintf(L"Unrecognized counter type.\n");
        fSuccess = FALSE;
        break;
    }

cleanup:

    return fSuccess;
}