EngQueryPerformanceFrequency function (winddi.h)
The EngQueryPerformanceFrequency function queries the frequency of the performance counter.
Syntax
ENGAPI VOID EngQueryPerformanceFrequency(
[out] LONGLONG *pFrequency
);
Parameters
[out] pFrequency
Pointer to a location that receives the performance counter frequency.
Return value
None
Remarks
The resolution of the timer is 1/x, where x is the value returned in the location to which pFrequency points. For example, if the value returned in pFrequency is 2 million, each tick is 1/2 millionth of a second. Each 1/x millionth increment of the count corresponds to one second of elapsed time.
A driver should call this routine sparingly. Frequent calls to EngQueryPerformanceFrequency can degrade the I/O performance for the calling driver and for the system as a whole.
Requirements
| Minimum supported client | Available in Windows 2000 and later versions of the Windows operating systems. |
| Target Platform | Universal |
| Header | winddi.h (include Winddi.h) |
| Library | Win32k.lib |
| DLL | Win32k.sys |