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

See also

EngQueryPerformanceCounter