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RequestWakeupLatency function

[RequestWakeupLatency is available for use in the operating systems specified in the Requirements section. It may be altered or unavailable in subsequent versions.]

Applies to: desktop apps only

Has no effect and returns STATUS_NOT_SUPPORTED. This function is provided only for compatibility with earlier versions of Windows.

Windows Server 2008 and Windows Vista: Has no effect and always returns success.

Windows Server 2003 and Windows XP:
Sets the requirement for roughly how quickly the computer should enter the working state.

Syntax

Copy

BOOL WINAPI RequestWakeupLatency(
  __in  LATENCY_TIME latency
);

Parameters

latency [in]

The latency requirement for the time is takes to wake the computer. This parameter can be one of the following values.

Value	Meaning
LT_LOWEST_LATENCY 1	PowerSystemSleeping1 state (equivalent to ACPI state S0 and APM state Working).
LT_DONT_CARE 0	Any latency (default).

Return value

The return value is nonzero.

Windows Server 2003 and Windows XP: If the function succeeds, the return value is nonzero. If the function fails, the return value is zero. The function will fail if the device does not support wake-up operations or if the system is entering the sleeping state.

Remarks

The system uses the wake-up latency requirement when choosing a sleeping state. The latency is not guaranteed because wake-up time is determined by the hardware design of the particular computer.

To cancel a latency request, call RequestWakeupLatency with LT_DONT_CARE.

Requirements