PoFxSetComponentResidency function (wdm.h)

Article
25/02/2022

The PoFxSetComponentResidency routine sets the estimated time for how long a component is likely to remain idle after the component enters the idle condition.

Syntax

C++

void PoFxSetComponentResidency(
  [in] POHANDLE  Handle,
  [in] ULONG     Component,
  [in] ULONGLONG Residency
);

Parameters

[in] Handle

A handle that represents the registration of the device with the power management framework (PoFx). The device driver previously received this handle from the PoFxRegisterDevice routine.

[in] Component

The index that identifies the component. This parameter is an index into the Components array in the PO_FX_DEVICE structure that the device driver used to register the device with PoFx. If the Components array contains N elements, component indexes range from 0 to N–1.

[in] Residency

The estimated residency time, in 100-nanosecond units. This parameter is a hint to PoFx about how long the component is likely to remain idle after a transition from the active condition to the idle condition. For more information, see Remarks.

Return value

None

Remarks

The calling driver supplies an estimated residency time that PoFx can use as a hint to improve performance. PoFx uses this hint to select an appropriate low-power Fx state for a component that is in the idle condition.

The device driver can call PoFxSetComponentResidency each time a change in circumstances requires a change in the estimated residency time. After each call, the new estimated residency time remains in effect until the driver calls PoFxSetComponentResidency again to update it.

If a component is in the idle condition when PoFxSetComponentResidency is called, PoFx might change the component’s Fx state to accommodate the new estimated residency time specified by the caller.

Requirements

Requirement	Value
Minimum supported client	Available starting with Windows 8.
Target Platform	Universal
Header	wdm.h
Library	Ntoskrnl.lib
DLL	Ntoskrnl.exe
IRQL	<= DISPATCH_LEVEL

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