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EXT_SET_PARAMETERS structure (wdm.h)

  • Article

The EXT_SET_PARAMETERS structure contains an extended set of parameters for the ExSetTimer routine.

Syntax

typedef struct _EXT_SET_PARAMETERS_V0 {
  ULONG    Version;
  ULONG    Reserved;
  LONGLONG NoWakeTolerance;
} EXT_SET_PARAMETERS, *PEXT_SET_PARAMETERS;

Members

Version

The version number of this EXT_SET_PARAMETERS structure. The ExInitializeSetTimerParameters routine sets this member to the correct version number.

Reserved

Set to zero. The ExInitializeSetTimerParameters routine sets this member to zero.

NoWakeTolerance

The maximum time, in system time units (100-nanosecond intervals), that the timer can wait to wake the processor after the timer reaches its expiration time. Only after the processor wakes can the timer expire. If a timer is set to expire when the processor is in a low-power state, the timer will not wake the processor to expire until the expiration time plus the NoWakeTolerance delay is exceeded. As an option, a driver can set this member to EX_TIMER_UNLIMITED_TOLERANCE, which indicates that the timer never wakes the processor and, thus, cannot expire until the processor wakes for some other reason.

Do not set this member to a negative value (other than EX_TIMER_UNLIMITED_TOLERANCE). Otherwise, the routine bug checks.

Remarks

The Parameters parameter of the ExSetTimer routine is a pointer to an EXT_SET_PARAMETERS structure. Before passing an EXT_SET_PARAMETERS structure to this routine, call the ExInitializeSetTimerParameters routine to initialize the structure.

The ExInitializeSetTimerParameters routine sets the NoWakeTolerance member to zero, which means that the timer immediately wakes the processor if the timer reaches its expiration time when the processor is in a low-power state. To reduce power consumption, a driver can set this member to a nonzero value to extend the time that the processor spends in a low-power state.

Requirements

Requirement Value
Minimum supported client Supported starting with Windows 8.1.
Header wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)

See also

ExInitializeSetTimerParameters

ExSetTimer