Synthesis: an efficient implementation of fundamental operating system services

This dissertation shows that operating systems can provide fundamental services an order of magnitude more efficiently than traditional implementations. It describes the implementation of a new operating system kernel, Synthesis, that achieves this level of performance. The Synthesis kernel combines several new techniques to provide high performance without sacrificing the expressive power or security of the system. The new ideas include: (1) Run-time code synthesis--a systematic way of creating executable machine code at runtime to optimize frequently-used kernel routines--queues, buffers, context switchers, interrupt handlers, and system call dispatchers--for specific situations, greatly reducing their execution time. (2) Fine-grain scheduling--a new process-scheduling technique based on the idea of feedback that performs frequent scheduling actions and policy adjustments (at sub-millisecond intervals) resulting in an adaptive, self-tuning system that can support real-time data streams. (3) Lock-free optimistic synchronization is shown to be a practical, efficient alternative to lock-based synchronization methods for the implementation of multiprocessor operating system kernels. (4) An extensible kernel design that provides for simple expansion to support new kernel services and hardware devices while allowing a tight coupling between the kernel and the applications, blurring the distinction between user and kernel services. The result is a significant performance improvement over traditional operating system implementations in addition to providing new services.