KeQueryDpcWatchdogInformation function (wdm.h)
The KeQueryDpcWatchdogInformation routine returns the deferred procedure call (DPC) watchdog timer values for the current processor.
Syntax
NTSTATUS KeQueryDpcWatchdogInformation(
[out] PKDPC_WATCHDOG_INFORMATION WatchdogInformation
);
Parameters
[out] 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 |
|---|---|
|
KeQueryDpcWatchdogInformation was called while a DPC was running on the current processor. |
|
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
| Requirement | Value |
|---|---|
| Minimum supported client | 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 |