PURPOSE: To realize a instruction number to totalizing device which counts and stores the number of times of request generation for processing a monitoring program of a computer and the record of the average number of instructions given to running machines required to complete processings requested to the monitoring program at every interruption of monitoring program calling instruction.

CONSTITUTION: When a monitoring program calling (SVC) instruction is issued from a program in question, the processor, in the course of the SVC instruction processing (start processing), sets a machine instruction counter 1 to the initial state (=0), and obtains from the interruption code of the SVC instruction addresses of entries of a monitoring program processing request generated number storing device and an average monitoring program running machine instruction number storing device 6 coresponding to the code and stores them in an address register 4. Then, a start/stop controlling mask latch 2 of the counter 1 is opened and the monitoring program is run after the SVC instruction is processed, and then, the number of various instructions issued at that time is counted by the counter 1. When the next PSW instruction is issued, the latch 2 is closed and the counting is stopped, and then, updating and edition of values in each storing device 5 and 6 are processed.