Preferably, after the earliest region is determined, the control portion updates at appropriate times the history information stored in the determined earliest region in {HEAD ~ accordance} with progress of the constant procedure before {TAIL ~ end} or interruption of the constant procedure in the input/output processing 
Preferably , after the earliest region is determined , the control portion updates at appropriate times the history information stored in the determined earliest region in { HEAD ~ accordance } with progress of the constant procedure before { TAIL ~ end } or interruption of the constant procedure in the input / output processing
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH