Design, Performance

Traditional debug methodologies are limited in their ability to provide debugging support for many-core parallel programming. Synchronization problems or bugs due to race conditions are particularly difficult to detect with software debugging tools. Most traditional debugging approaches rely on globally syn-chronized signals, but these pose problems in terms of scalabili-ty. The first contribution of this paper is to propose a novel non-uniform debug architecture (NUDA) based on a ring intercon-nection schema. Our approach makes debugging both feasible and scalable for many-core processing scenarios. The key idea is to distribute the debugging support structures across a set of hierarchical clusters while avoiding address overlap. This allows the address space to be monitored using non-uniform protocols. Our second contribution is a non-intrusive approach to race detection supported by the NUDA. A non-uniform page-based monitoring cache in each NUDA node is used to watch the access footprints. The union of all the caches can serve as a race detection probe. Using the proposed approach, we show that parallel race bugs can be precisely captured, and that most false-positive alerts can be efficiently eliminated at an average slow-down cost of only 1.4%~3.6%. The net hardware cost is relative-ly low, so that the NUDA can readily scale increasingly com-plex many-core systems