Application System/400 Performance Characteristics

The operating system for Application System/400" (AS/400m) provides an unprecedented breadth of function and system services in a single, integrated system. The majority of functions are implemented on top of an abstract, high-level machine interface in a hardware independent manner, using many architectural characteristics normally associated with poor performance. Despite these architectural and functional traits of the operating system, the AS1400 exhibits excellent price and performance characteristics for commercial applications and is a competitive system in the mid-range commercial application arena. A number of design and optimization techniques, many of them unique or innovative, were incorporated into the AS1400 to achieve a combination of advanced design, function, and performance and are the main subjects discussed in this paper. M any of the basic architectural Characteristics of the hardware and operating system of Application System/400'" (~ ~ 1 4 0 0 ~ ~) originated with the System/38, one of its predecessors. Some of the basic system objectives and requirements underlying the design of the System/38 included: hardware independence for the operating system, enhanced productivity for system and application programmers, optimization of system for interactive processing, greater integrity and reliability for interactive processing , major usability improvement over predecessor systems, extendability for the operating system and its applications, and leading-edge commercial application support. The System/38 requirements applied equally well (if not more so) to the development of the AS1400 family of computers. In addition, several major objectives also existed for the A S ~ O O , including compatibility with System/36, System/38, and Systems Application Architecture; a selection of products ranging from the size of System/36 to double the size of System/38; improved personal computer affinity via seamless interfaces; and market leadership in communications. Some of the key ~ ~ 1 4 0 0 architectural characteristics that were developed to support these objectives included: High-level, abstract machine interface (MI) Pervasive late binding Capability-based (object-oriented) operating sys-Segment-based virtual addressing (hardware and Relational database management system (RDBMS) High level of inherent operating system integrity tem (Operating System/400") licensed internal code) and reliability Copying in printed form for private use is permitted without payment of royalty provided that (1) each reproduction is done without alteration and (2) the Journal reference and IBM copyright notice are included on the first page. The title and abstract, but no other portions, of this paper may be copied or distributed royalty free without further permission by computer-based and other …