Motivation:
In order to decrease the latency of a prioritized request (such as READ
requests) the device driver might decide to stop the transmission of a
current "low priority" request in order to handle the "high priority" one.
The urgency of the request is decided by the block layer I/O schedul
Urgent request notification stops currently running transaction
on bus.
In order to decrease a latency of a prioritized requests (aka Urgent
request), we might want to stop the transmission of a running "low
priority" request in order to handle the Urgent request. The urgency of
the request is deci
