In this paper, we present the design and implementation of an Open Computing Language (OpenCL) framework that targets heterogeneous accelerator multicore architectures with local memory. The architecture consists of a general-purpose processor core and multiple accelerator cores that typically do not have any cache. Each accelerator core, instead, has a small internal local memory. Our OpenCL runtime is based on software-managed caches and coherence protocols that guarantee OpenCL memory consistency to overcome the limited size of the local memory. To boost performance, the runtime relies on three source-code transformation techniques, work-item coalescing, web-based variable expansion and preload-poststore buffering, performed by our OpenCL C source-to-source translator. Work-item coalescing is a procedure to serialize multiple SPMD-like tasks that execute concurrently in the presence of barriers and to sequentially run them on a single accelerator core. It requires the webbased variable expansion technique to allocate local memory for private variables. Preload-poststore buffering is a buffering technique that eliminates the overhead of software cache accesses. Together with work-item coalescing, it has a synergistic effect on boosting performance. We show the effectiveness of our OpenCL framework, evaluating its performance with a system that consists of two Cell BE processors. The experimental result shows that our approach is promising.
A specification and validation technique for dynamic systems is proposed. In particular, a new temporal logic, called HDTL, is presented and the tableau method revised for automatic analysis. Using a freeze quantifier, HDTL with the revised tableau method makes it possible to specify the correctness requirements of dynamic systems and validate them. The proposed logic is rather generic, i.e. it has only a few assumptions on operational language. The authors introducc a simple dynamic modelling language and illustrate its experiment. The experiment shows that HDTL is suitable for specifying dynamic properties and the analysis technique is promising.
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