Windows Dev Center
Base Counter Types

Some formulas require both a counter property and base property. The base value is the denominator in the formula for the counter type. In raw data Performance Counter Classes derived from Win32_PerfRawData, the base property must immediately follow the counter property. The base property must have the same name as the preceding counter, with _Base appended.

For example, the AvgDiskBytesPerRead property in Win32_PerfRawData_PerfDisk_LogicalDisk contains the raw value, in bytes, transferred from the disk during read operations. It has a base property, AvgDiskBytesPerRead_Base, which represents the accumulated number of operations. When WMI applies the formula for the specified counter type, PERF_AVERAGE_BASE, AvgDiskBytesPerRead is divided by AvgDiskBytesPerRead_Base to produce the average value. This value appears in System Monitor and is stored in the corresponding Win32_PerfFormattedData_PerfDisk_LogicalDisk property. Base properties are only used in raw data classes.

In classes derived from Win32_PerfFormattedData, the Counter qualifier specifies the numerator property in the raw class and the Base qualifier specifies the base denominator property.

The following table lists the CounterType constant values.

CounterType ConstantDescription
PERF_AVERAGE_BASE

Decimal 1073939458

Base value used to calculate the PERF_AVERAGE_TIMER and PERF_AVERAGE_BULK counter types.
PERF_COUNTER_MULTI_BASE

Decimal 1107494144

Base value used to calculate the PERF_COUNTER_MULTI_TIMER, PERF_COUNTER_MULTI_TIMER_INV, PERF_100NSEC_MULTI_TIMER, and PERF_100NSEC_MULTI_TIMER_INV counter types.
PERF_LARGE_RAW_BASE

Decimal 1073939712

Base value found in the calculation of PERF_RAW_FRACTION, 64 bits.
PERF_RAW_BASE

Decimal 1073939459

Base value used to calculate the PERF_RAW_FRACTION counter type.
PERF_SAMPLE_BASE

Decimal 1073939457

Base value used to calculate the PERF_SAMPLE_COUNTER and PERF_SAMPLE_FRACTION counter types.

## Related topics

WMI Performance Counter Types
Counter Types