STM concurrency control for embedded real-time software with tighter time bounds

Abstract

We consider software transactional memory (STM) concurrency control for multicore real-time software, and present a novel contention manager (CM) for resolving transactional conflicts, called length-based CM (or LCM). We upper bound transactional retries and response times under LCM, when used with G-EDF and G-RMA schedulers. We identify the conditions under which LCM outperforms previous real-time STM CMs and lock-free synchronization. Our implementation and experimental studies reveal that G-EDF/LCM and G-RMA/LCM have shorter or comparable retry costs and response times than other synchronization techniques.

On real-time STM concurrency control for embedded software with improved schedulability

“…ECM and RCM [5] use dynamic and fixed priorities, respectively, to resolve conflicts. ECM uses G-EDF, and allows the transaction whose job has the earliest absolute deadline to commit first [6].…”

“…To use STM in real-time systems, transactional retry cost must be bounded in order to satisfy time constraints. ECM's retry cost is bounded in [5] as follows:…”

“…Retry cost under RCM is similar to ECM, except that, only tasks with higher priority than τ i can interfere with any job τ x i of τ i . RCM's retry cost is also bounded in [5].…”

“…Past real-time CM research has proposed resolving transactional contention using dynamic and fixed priorities of parent threads, resulting in Earliest Deadline First CM (ECM) and Rate Monotonic CM (RCM), respectively [6,5,4]. In particular, [5] shows that ECM and RCM achieve higher schedulability -i.e., greater number of task sets meeting their time constraints -than lock-free synchronization only under some ranges for the maximum atomic section length. That range is significantly expanded with the Length-based CM (LCM) in [4], increasing the coverage of STM's timeliness superiority.…”

Multi-resource Real-Time Reader/Writer Locks for Multiprocessors

“…In prior work on STM, both throughput-oriented systems (the literature here is quite vast-please see [10] and the references therein) and real-time systems [1,11,12,14,15] have been considered. In all work (known to us) on STM for real-time systems, the focus has been on non-blocking approaches.…”