ABSTRACT

Simultaneous Multithreading (SMT) enables fine-grain resource sharing of a single super-scalar processor among multiple tasks, improving cost-performance. However, SMT cannot be safely exploited in hard-real-time systems. These systems require analytical frameworks for making worst-case performance guarantees. SMT violates simplifying assumptions for de-riving worst-case execution times (WCET) of tasks. Classic real-time theory uses single-task WCET analysis, where a task is assumed to have access to dedicated processor resources, hence, its WCET can be derived independent of its task-set context. This is not true for SMT, where tasks interfere due to resource sharing. Modeling interference requires whole task-set WCET analysis, but this approach is futile since co-scheduled tasks vary and compete for re-sources arbitrarily. Thus, formally proving real-time guarantees for SMT is intractable. This dissertation proposes flexible interference-free multithreading. Interference-free par-titioning guarantees that the performance of a single task is not affected by its workload context (hence, preserving single-task WCET analysis), while flexible resource sharing emulates fine-grain resource sharing of SMT to achieve similar cost-performance efficiency. The Real-time Virtual Multiprocessor (RVMP) paradigm virtualizes a single superscala