Software Performance Modeling and Management

This paper addresses methods to assess the impact of software on weapon system performance parameters such as reliability and operability/suitability. The latter is emphasized in major weapon-system go-ahead decisions. This paper discusses a system reliability model primarily intended to provide management insight and guidelines for identifying out-of-tolerance situations and needed corrective actions. Guidelines are discussed for judging if ``independent verification and test´´ and ``weapon-system proof-of-compliance testing´´ are successful. Guidelines are provided for comparing software and hardware in terms of total valid problems reported, resolution rates, and comparable difficulty of implementing and verifying the resolutions. This is done with respect to severity levels in MIL-STD-1679. The management of the operability/suitability issue is discussed and recommendations are made to both the procuring agency and the prime contractor. Software is an attractive medium in comparison to hardware in implementing complex functions because: a) there are more controllable means to reduce severe software defects, and b) it is easier to effect change. Properly managed software will have minimal difficulties with system reliability and operability/suitability. Proper software management includes: a) the application, during development, of proper design tools such as top-down design, structural programming, and programming teams; b) aggressive, independent testing and problem tracking activities; and c) application of the management elements presented in this paper. Such application requires contractor familiarity with user needs and capabilities as well as with the mission and operations of the system, so as to optimize the man/machine interface.