Avoiding DPC Watchdog timeout problems in StorPort Miniports

This article helps you resolve the DPC Watchdog timeout problems in StorPort Miniports.

Original product version:   Windows DPC Watchdog
Original KB number:   2569413


The system stops responding; for example, the keyboard and mouse don't work. If a kernel debugger is attached to the system, the debugger may show an assertion.


StorPort.sys handles I/O completions in a routine that runs at DISPATCH_LEVEL and that serially calls the I/O completion routines of all IRPs that have completed. If I/O completion routines singly or together take too much time, the keyboard and/or mouse may stop responding. It is also possible that the Windows DPC Watchdog timer routine will decide that the StorPort routine has taken excessive time to finish.


A kernel driver in the storage stack can reduce the problem's likelihood by efficient coding of the driver's I/O completion routine. If it is still not possible to do all necessary processing in the completion routine in enough time, the routine can create a work element for the I/O work, queue up the element to a work queue and return STATUS_MORE_PROCESSING_REQUIRED; a worker thread of the driver should then find the work element, do the work and do IoCallerDriver for the IRP to ensure the IRP's further I/O processing.

For more information about  handling IRPs, see Different ways of handling IRPs - Cheat sheet   - (part 1 of 2)

More information

In a kernel dump or in a live kernel debugging session, storport!RaidUnitCompleteRequest may appear in the execution stack running on a CPU.