Browsing by Author "Yang, Chia-Lin"

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Analyzing OpenCL 2.0 Workloads Using a Heterogeneous CPU-GPU Simulator
(2017-01-01)
Wang, Li
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Tsai, Ren-Wei
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Wang, Shao-Chung
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Chen, Kun-Chih
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Wang, Po-Han
Heterogeneous CPU-GPU systems have recently emerged as an energy-efficient computing platform. A robust integrated CPU-GPU simulator is essential to facilitate researches in this direction. While few integrated CPU-GPU simulators are available, similar tools that support OpenCL 2.0, a widely used new standard with promising heterogeneous computing features, are currently missing. In this paper, we extend the existing integrated CPU-GPU simulator, gem5-gpu, to support OpenCL 2.0. In addition, we conduct experiments on the extended simulator to see the impact of new features introduced by OpenCL 2.0. Our OpenCL 2.0 compatible simulator is successfully validated against a state-of-the-art commercial product, and is expected to help boost future studies in heterogeneous CPU-GPU systems.
Improving Read Performance of NAND Flash SSDs by Exploiting Error Locality
(2016-04)
Liu, Ren-Shuo
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Chuang, Meng-Yen
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Yang, Chia-Lin
;
Li, Cheng-Hsuan
;
Ho, Kin-Chu
NAND flash-based solid-state drives (SSDs), which can serve as the caches of hard disk drives, have gained popularity in large-scale, high-performance storage. A type of advanced error correction code for SSDs, low-density parity-check (LDPC), is required to mitigate a considerable number of errors in the raw data of NAND flash. However, LDPC imposes read performance overhead due to the complex decoding procedure of LDPC. In this paper, we propose an error-correcting cache (EC-Cache) that exploits "error locality", a characteristic of NAND flash memory, to improve the read performance of SSDs. We use the term "error locality" to refer to the property that the majority of errors in reads to the same flash page appear at the same positions until the page is erased. By caching detected errors, we can correct a significant portion of errors in the requested flash page prior to the LDPC decoding process. This design significantly reduces LDPC decoding overhead because the latency of LDPC is correlated with the number of errors in the input data. We conduct experiments, including flash characterization, LDPC simulation, and SSD simulation, to evaluate EC-Cache. The experimental results demonstrate that EC-Cache can improve the read performance of LDPC-based SSDs by up to 2:6 x.