Performance Evaluation of a Dynamically Switchable SIMD/MIMD Processor by Using an Image Recognition Application

概要

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We have developed an “XC core” processor that achieves low cost, high performance, and low power consumption through the use of a highly parallel SIMD architecture (the SIMD mode), as well as achieves high flexibility by morphing into a MIMD architecture (MIMD mode). In this paper, we evaluate the effectiveness of the MIMD mode by using a white line detection algorithm for open roads. Our evaluation shows that the algorithm can be processed in real time (less than 33ms) by using the MIMD mode to execute verification of white line segments, which is a part of the algorithm not suitable to be executed by the SIMD mode. We also show that the verification can be executed five times faster by using region of interest (ROI) transfer instructions to efficiently transfer the ROI of an image. Furthermore, we also measured the execution time in the MIMD mode with changing the number of processing units (PUs) used, from 2 to 4, 8, 16 and 32. The measured results show that the performance improvement rate slows down when using more than 16 PUs in the MIMD mode, mainly due to insufficient parallelism in the verification process. Overall, a 10.68 times speedup was achieved by using 32 PUs in the MIMD mode, compared with only using the SIMD mode.