# Basic Algorithm Counter Types

Basic algorithm counter types generally represent differences between samples over time, and often use a base value for the calculation. For example, the **PercentFreeSpace** property of the **Win32_PerfFormattedData_PerfDisk_PhysicalDisk** class represents the ratio of the free space available on the physical disk unit to the total usable space provided by the selected physical disk drive. This class also contains the base value, **PercentFreeSpace_Base**. The percentage of free disk space is obtained by dividing **PercentFreeSpace** by **PercentFreeSpace_Base** and multiplying by 100%.

The basic algorithms in the following table are provided.

CounterType Constant | Description |
---|---|

PERF_RAW_FRACTION Decimal 537003008 | Ratio of a subset to its set as a percentage. This counter type displays the current percentage only, not an average over time. |

PERF_SAMPLE_FRACTION Decimal 549585920 | Average ratio of hits to all operations during the last two sample intervals. This counter type requires a base property with the PERF_SAMPLE_BASE counter type. |

PERF_COUNTER_DELTA Decimal 4195328 | This counter type shows the change in the measured attribute between the two most recent sample intervals. |

PERF_COUNTER_LARGE_DELTA Decimal 4195584 | Same as PERF_COUNTER_DELTA but a 64-bit representation for larger values. |

PERF_ELAPSED_TIME Decimal 807666944 | Total time between when the process started and the time when this value is calculated. |

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