Tools, Techniques, and Trade-offs when Porting Large Software Systems to New Environments

Abstract: Computer hardware and software evolve very fast. With the advent of chip-multiprocessors and symmetric multithreading, multiprocessor hardware configurations are becoming prevalent. For software, new hardware and requirements such as security, performance and maintainability drive the development of new runtime environments, virtual machines and programming methodologies. These trends present problems when porting legacy software. Multiprocessor hardware require ports of uniprocessor operating system kernels while new software environments might require that programs have to be ported to different languages. This thesis examines the tradeoff between performance and development effort for software porting with case studies in operating system porting to multiprocessors and tool support for porting C and C++ applications to Java virtual machines. The thesis consists of seven papers. The first paper is a survey of existing multiprocessor development approaches and focuses on the tradeoff between performance and implementation effort. The second and third papers describe the evolution a traditional lock-based multiprocessor port, going from a serialized “giant locked” port and evolving into a coarse-grained implementation. The fourth paper instead presents an alternative porting approach which aims to minimize development effort. The fifth paper describes a tool for efficient instrumentation of programs, which can be used during the development of large software systems such as operating system kernels. The sixth and seventh papers finally describe a binary translator which translates MIPS binaries into Java bytecode to allow low-effort porting of C and C++ applications to Java virtual machines. The first main contributions of this thesis is an in-depth investigation of the techniques used when porting operating system kernels to multiprocessors, focusing on development effort and performance. The traditional approach used in the second and third papers required longer development time than expected, and the alternative approach in the fourth paper can therefore be preferable in some cases. The second main contribution is the development of a binary translator that targets portability of C and C++ applications to J2ME devices. The last two papers show that the approach is functional and has good enough performance to be feasible in real-life situations.