Obtains a counter sample and returns the calculated value for it.
Assembly: System (in System.dll)
The instance is not correctly associated with a performance counter.
An error occurred when accessing a system API.
The platform is Windows 98 or Windows Millennium Edition (Me), which does not support performance counters.
Code that is executing without administrative privileges attempted to read a performance counter.
If the calculated value of a counter depends on two counter reads, the first read operation returns 0.0. Resetting the performance counter properties to specify a different counter is equivalent to creating a new performance counter, and the first read operation using the new properties returns 0.0. The recommended delay time between calls to the method is one second, to allow the counter to perform the next incremental read.
To read performance counters, you must have administrative privileges. In Windows Vista, User Account Control (UAC) determines the privileges of a user. If you are a member of the Built-in Administrators group, you are assigned two run-time access tokens: a standard user access token and an administrator access token. By default, you are in the standard user role. To execute the code that accesses performance counters, you must first elevate your privileges from standard user to administrator. You can do this when you start an application by right-clicking the application icon and indicating that you want to run as an administrator.