The functions in extensible counters might return inconsistent or unreadable data buffers to Performance Library. At a minimum, this could result in invalid counter values; at its worst, it could cause the operating system to stop. Thus, by default, Performance Library tests these data buffers thoroughly for errors and internal consistency. However, these tests have some overhead, so Windows NT lets you reduce the level of testing.
If you are not using extensible counters or if your extensible counters have been proven to be reliable, reducing the test level will reduce the processor load. If, however, you install a new product with performance counters, or if the system is being used to develop or test extensible counters, you can increase the test level.
Performance Library has three levels for testing the data buffers returned by functions of extensible counters. Note that 1 represents the highest level and 3 represents the lowest level.
Test level | Description | |
1 | Thorough testing of buffer pointers and contents. (This is the default.) | |
2 | Minimal testing of overall buffer length and pointers, but not of contents. | |
3 | No testing. | |
To adjust the test level , use a Registry Editor, such as Regedt32.exe, to add or change the ExtCounterTestLevel value entry, and then restart Performance Monitor.
Subtree | HKEY_LOCAL_MACHINE |
Key | \Software\Microsoft\WindowsNT\CurrentVersion\Perflib |
Name | ExtCounterTestLevel |
Type | REG_DWORD |
Values | 1, 2, 3 |
Check the Application Event Log routinely. You can use the Find or Filter Events options to display events with Source = PERFLIB.
If you encounter errors with extensible counters, consult the provider.