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NF:ntifs.PoSetDeviceBusyEx |
PoSetDeviceBusyEx function (ntifs.h) |
Learn more about the PoSetDeviceBusyEx routine. |
kernel |
07/06/2023 |
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PoSetDeviceBusyEx, PoSetDeviceBusyEx routine [Kernel-Mode Driver Architecture], kernel.posetdevicebusyex, portn_62143669-4381-4b4b-8d23-8b315d882c65.xml, wdm/PoSetDeviceBusyEx |
ntifs.h |
Wdm.h, Ntddk.h, Ntifs.h |
Universal |
Windows Vista with SP1 |
NtosKrnl.lib |
NtosKrnl.exe |
Any level |
Windows |
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The PoSetDeviceBusyEx routine notifies the power manager that the device associated with the specified idle counter is busy.
A pointer to an idle counter. This is a pointer value that was previously returned by the PoRegisterDeviceForIdleDetection routine. Because PoRegisterDeviceForIdleDetection might return a NULL pointer, the caller must verify that the pointer is non-NULL before it calls PoSetDeviceBusyEx.
This routine is a direct replacement for the PoSetDeviceBusy macro. If you are writing new driver code for Windows Vista with Service Pack 1 (SP1) and later versions of Windows, call PoSetDeviceBusyEx instead of PoSetDeviceBusy.
A driver calls the PoSetDeviceBusyEx and PoRegisterDeviceForIdleDetection routines to enable system idle detection for its device. If a device that is registered for idle detection stays idle for the driver-specified time-out period, the power manager sends an IRP_MN_SET_POWER request to put the device in a requested sleep state.
PoSetDeviceBusyEx reports that the device is busy, so that the power manager can restart its idle countdown. If the device is in a sleep state, PoSetDeviceBusyEx does not change the state of the device. That is, it does not cause the system to send an IRP_MN_SET_POWER request to awaken the device.
PoSetDeviceBusyEx is designed for use with I/O operations that are relatively brief compared to the time-out period of the idle counter. For longer operations that might exceed this period, use the PoStartDeviceBusy and PoEndDeviceBusy routines instead.
A driver that makes multiple requests for brief I/O operations should call PoSetDeviceBusyEx for every I/O request that it makes.