David B. Emmes

Adaptive algorithms for managing a distributed data processing workload

Workload management, a function of the OS/390™ operating system base control program, allows installations to define business objectives for a clustered environment (Parallel Sysplex™ in OS/390). This business policy is expressed in terms that relate to business goals and importance, rather than the internal controls used by the operating system. OS/390 ensures that system resources are assigned to achieve the specified business objectives. This paper presents algorithms developed to simplify performance management, dynamically adjust computing resources, and balance work across parallel systems. We examine the types of data the algorithms require and the measurements that were devised to assess how well work is achieving customer-set goals. Two examples demonstrate how the algorithms adjust system resource allocations to enable a smooth adaptation to changing processing conditions. To the customer, these algorithms provide a single-system image to manage competing workloads running across multiple systems.

Building a Java virtual machine for server applications: the Jvm on 0S/390

As the use of the JavaTM language and virtual machines proliferates beyond the sphere of applets into the space of server programs, developers are requiring better performance, availability, and transactional and scalability features. This paper describes the work done for the Operating System/390 (OS/390®) Java virtual machine to improve performance and serviceability, to introduce security and performance enhancements, and to redesign parts of the virtual machine to enable it to run server programs efficiently and safely. Although OS/390 was the motivating platform for these changes, Java server programs on any platform can benefit from these features.