There is a sleep() method which is called 3 times in the SCSI controller (DataIn(), DataOut(), Status()). The comments in the source say "Minimum execution time", but I am not aware of a minimum execution time being mentioned in the SCSI standard. In addition, when there are no data to be transferred DataIn() and DataOut() effectively sleep twice, because there is also a call to sleep in Status():

		// Minimum execution time
		if (execstart > 0) {
			Sleep();             <--- First sleep()
		}

		// If the length is 0, go to the status phase
		if (!HasValidLength()) {
			Status();        <--- Second sleep() in the Status() method
			return;
		}

After removing the Sleep() method and testing the result I could not find anything wrong. What is the reason for sleeping, and why do DataIn() and DataOut() effectively sleep twice?

Also see #1287.