Performance Trace Facility
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
A facility traces program flow and measures the pathlengths of multiple program modules executing in a computer system. The computer system has RAM and ROS storage. A program assist enables a logic analyzer to capture subprogram trace information in one measurement run. At the start and end of each program procedure, an instruction that writes a unique number (procedure ID) to a predefined fixed ROS address is inserted. Each program procedure is assigned a pair of these IDs. Fig. 1 shows an example of procedures writing to the ROS address. During execution, the single ROS location will be accessed by all the program procedures that execute. The write to the ROS location has no effect on the system other than surfacing to a data bus the procedure IDs for the logic analyzer to easily capture.