Performance Analysis of ClearSpeed's CSX600 Interconnects

ClearSpeed's CSX600 that consists of 96 Processing Elements (PEs) employs a one-dimensional array topology for a simple SIMD processing. To clearly show the performance factors and practical issues of NoCs in an existing modern many-core SIMD system, this paper measures and analyzes NoCs of CSX600 called Swazzle and ClearConnect. Evaluation and analysis results show that the sending and receiving overheads are the major limitation factors to the effective network bandwidth. We found that (1) the number of used PEs, (2) the size of transferred data, and (3) data alignment of a shared memory are three main points to make the best use of bandwidth. In addition, we estimated the best- and worst-case latencies of data transfers in parallel applications.