KeQueryDpcWatchdogInformation function

The KeQueryDpcWatchdogInformation routine returns the deferred procedure call (DPC) watchdog timer values for the current processor.

Syntax

NTKERNELAPI NTSTATUS KeQueryDpcWatchdogInformation(
  PKDPC_WATCHDOG_INFORMATION WatchdogInformation
);

Parameters

WatchdogInformation

A pointer to a caller-supplied KDPC_WATCHDOG_INFORMATION structure. The routine writes the current DPC watchdog timer values to this structure.

Return Value

KeQueryDpcWatchdogInformation returns an NTSTATUS value. Possible return values include the following status codes.

Return code Description
STATUS_SUCCESS
KeQueryDpcWatchdogInformation was called while a DPC was running on the current processor.
STATUS_UNSUCCESSFUL
The current processor was not running a DPC when KeQueryDpcWatchdogInformation was called.

Remarks

The KeQueryDpcWatchdogInformation routine can be called from a DPC routine or at an IRQL= DISPATCH_LEVEL to determine the amount of time that remains before a DPC time-out occurs. The operating system implements a DPC watchdog timer to detect when a single DPC routine runs for too long, or when a series of queued DPC routines runs back-to-back for too long. If DPC time-out errors are enabled, and if either a DPC routine exceeds the time limit for a single routine, or a series of DPC routines exceeds the aggregate time limit, a DPC_WATCHDOG_VIOLATION (0x133) bug check occurs.

KeQueryDpcWatchdogInformation must be called while a DPC is running or invoked at an IRQL= DISPATCH_LEVEL or higher on the current processor. Otherwise, the call fails and returns STATUS_UNSUCCESSFUL.

DPC routines should run only for brief periods, and should delegate as much processing as possible to worker threads. To avoid degrading system responsiveness, a typical DPC routine should run for no more than 100 microseconds each time it is called. For more information, see Guidelines for Writing DPC Routines.

Requirements

   
Windows version Available starting with Windows Vista.
Target Platform Universal
Header wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library NtosKrnl.lib
DLL NtosKrnl.exe
IRQL DISPATCH_LEVEL

See Also

KDPC_WATCHDOG_INFORMATION