It is possible for a single extensible performance counter DLL to provide performance information for one or more applications, drivers, or services. Each software component that provides performance counters must store the following configuration information in the registry.
| Configuration Item | Description |
|---|---|
| DLL name | The name of the DLL that contains the functions used by the performance registry. |
| Open procedure | This function is called once when the software component's performance interface is first started. It is used to initialize the DLL. |
| Collect procedure | This function is called repeatedly to collect the current performance data for the software component. |
| Close procedure | This function is called when the handle to the performance registry is closed. |
| Counter and help identifiers | These strings identify the counter and object names that are stored in the registry and referenced by a numeric index. The index values for extensible counters are defined when the DLL is installed. This is usually during application or service installation. Some extensible counter DLLs use pre-assigned index values. The index values for those counters are not displayed; instead, N/A appears. |