Implementation of Nexus: Dynamic Hardware Management Support for Multicore Platforms

Current trends in computer architecture focus on multicore platforms. The target of these new platforms is to scale the performance of the system with the number of cores. However, the performance of current archictectures is limited due to thread-level parallelism overhead and programmability. StarSS is a task-based programming model that eases the programmability of multicores and tries to exploit functional parallelism within applications. However, the performance of StarSS does not scale efficiently for fine-grained tasks, as for such tasks the task management overhead becomes significant in comparison to the execution of the tasks. Nexus is a dynamic hardware support system that aims to alleviate the current overhead of StarSS, by offloading the dependency resolution process and the synchronization with the cores to hardware. In this work, we implement Nexus by defining and connecting the new hardware in a Cell archictecture simulator. The scalability, performance, and throughput of the implementation are evaluated for different task sizes and number of cores, using several dependency patterns. Furthermore, different configuration parameters are evaluated, such as the dimension of the new hardware inserted in the existing architecture. Results show a large improvement of the scalability offered by Nexus in comparison with StarSS, especially for fine-grained tasks. Nexus succeeds at alleviating the overhead of StarSS by accelerating the dependency resolution process and the synchronization with the worker cores. Furthermore, the evaluation of the Nexus system dimensions has shown that its scalability decreases slightly with its area.Embedded SystemsComputer EngeneeringElectrical Engineering, Mathematics and Computer Scienc