Is it possible to retrieve the CPU that created a WDFREQUEST?

Question

I am trying to affinitise the completion of CompleteRequest to the CPU that originally issued the request. Is there a way to retrieve the CPU that issued the request during FdoDeviceControl or any onother way to see where the request came from before it entered the dispatch queue?

Answer 1

Once you are in a DPC routine it's too late to tell where the request originated. You need to call KeGetCurrentProcessorNumberEx() before you queue the request to a DPC queue. I assume the request is an IRP...?