Browsing by Author "Chen, Kuan-Ting"

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A High-Performance Double-Layer Counting Bloom Filter for Multicore Systems
(2015-11-01)
Lai, Bo-Cheng Charles
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Chen, Kuan-Ting
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Wu, Ping-Ru
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The snoopy-based protocol is a widely used cache coherence mechanism for a symmetric multiprocessor (SMP) system. However, this broadcast-based protocol blindly disseminates data sharing information across the system, and introduces many unnecessary data operations. This paper proposes a novel architecture of double-layer counting Bloom filter (DLCBF) to reduce the unnecessary data lookups on the local cache and redundant data transactions on the shared interconnection of an SMP system. By adding an extra filtering layer, the DLCBF effectively exploits the data locality of applications. The two-layer hierarchy reduces the storage size of DLCBF by 18.75%, and achieves 81.99% and 31.36% better filtering rates when compared with a classic Bloom filter (BF) and original counting BF, respectively. When applied on the segmented shared bus of an SMP system, the DLCBF outperforms the previous work by 58% for In-filters and 1.86x for Out-filters. This paper also comprehensively explores the key design parameters of DLCBF, including the sizes of top-layer, bottom-layer, and multilayer design. The results show that enlarging the layer filters enhance the filtering rates of DLCBF, while adding an extra filter layer only provides slight benefit.
High morphology stability and ambipolar transporting host for use in blue phosphorescent single-layer organic light-emitting diodes
(2014-11-01)
Hsu, Fang-Ming
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Chien, Liang-Jung
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Chen, Kuan-Ting
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Li, Ya-Ze
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Liu, Shun-Wei
The authors report a small molecule host of 2,7-bis(diphenylphosphoryl)-9-[4-(N, N-diphenylamino)phenyl]-9-phenylfluorene (POAPF) doped with 8 wt% iridium(III)-bis[(4,6-difluorophenyl)pyridinato-N,C-2\']picolinate (FIrpic) for use in efficient and single-layer blue phosphorescent organic light-emitting diodes (PHOLEDs) exhibiting a maximum external quantum efficiency of similar to 20.3% at brightness of 100 cd/m(2). The high performance of such single layer PHOLEDs is attributed to the POAPF host\'s high morphological stability, suitable triplet energy level, and equal charge carrier mobilities of hole and electron to form the broad carrier recombination zone in the emitting layer, thus reducing the triplet-triplet annihilation and resulting in a slight efficiency roll off of 0.5% from the brightness of 1 and 1000 cd/m(2). This work also systematically investigated the arrangement of the POAPF:FIrpic recombination zone for optimizing the performance of the single layer PHOLED. (C) 2014 Elsevier B.V. All rights reserved.
MEMORY CAPACITY AWARE NON-BLOCKING DATA TRANSFER ON GPGPU
(2013)
Liu, Hao-Wei
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Kuo, Hsien-Kai
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Chen, Kuan-Ting
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Lai, Bo-Cheng Charles
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電子工程學系及電子研究所
The massive data demand of GPGPUs requires expensive memory modules, such as GDDR, to support high data bandwidth. The high cost poses constraints on the total memory capacity available to GPGPUs, and the data need to be transferred between the host CPUs and GPGPUs. However, the long latency of data transfers has resulted in significant performance overhead. To alleviate this issue, the modern GPGPUs have implemented the non-blocking data transfer allowing a GPGPU to perform computing while the data is being transmitted. This paper proposes a capacity aware scheduling algorithm that exploits the non-blocking data transfer in modern GPGPUs. By effectively taking the advantage of non-blocking transfers, experiment results demonstrate an average of 24.01% performance improvement when compared to existing approaches that only consider memory capacity.
Reduce Data Coherence Cost with An Area Efficient Double Layer Counting Bloom Filter
(2012)
Chen, Kuan-Ting
;
Wu, Ping-Ru
;
Lai, Bo-Cheng Charles
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The snoopy protocol is a widely used scheme to maintain cache coherence. However, the protocol requires a broadcast scheme and forces substantial unnecessary data searches at the local cache. This paper proposes a novel Double Layer Counting Bloom Filter (DLCBF) to significantly reduce the redundant data searches and transmission. The DLCBF implements an extra layer of hash function and the counting feature at each filter entry. By using the hierarchical structure of the hash function, DLCBF can effectively increase the successful filter rates while requiring a smaller memory usage than the conventional Bloom filters. Experimental results show that the DLCBF can screen out 4.05X of unnecessary cache searches and use 18.75% less memory compared to conventional Bloom filters. The DLCBF is also used to filter out the redundant data transmission on a hierarchical shared bus. Simulation results show that the DLCBF outperforms conventional filters by 58% for local transmissions and 1.86X for remote transmissions.
The effects of hydrogen plasma pretreatment on the formation of vertically aligned carbon nanotubes
(2007-09-30)
Wang, Wen-Pin
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Wen, Hua-Chiang
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Jian, Sheng-Rui
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Juang, Jenh-Yih
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Lai, Yi-Shao
The effects of H-2 plasma pretreatment on the growth of vertically aligned carbon nanotubes (CNTs) by varying the flow rate of the precursor gas mixture during microwave plasma chemical vapor deposition (MPCVD) have been investigated in this study. Gas mixture of H-2 and CH4 with a ratio of 9:1 was used as the precursor for synthesizing CNTs on Ni-coated TiN/Si(1 0 0) substrates. The structure and composition of Ni catalyst nanoparticles were investigated by using scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (XTEM). Results indicated that, by manipulating the morphology and density of the Ni catalyst nanoparticles via changing the flow rate of the precursor gas mixture, the vertically aligned CNTs could be effectively controlled. The Raman results also indicated that the intensity ratio of the G and D bands (I-D/I-G) is decreased with increasing gas flow rate. TEM results suggest H-2 plasma pretreatment can effectively reduce the amorphous carbon and carbonaceous particles and. thus. is playing a crucial role in modifying the obtained CNTs structures. (c) 2007 Elsevier B.V. All rights reserved.
Thread Affinity Mapping for Irregular Data Access on Shared Cache GPGPU
(2012)
Kuo, Hsien-Kai
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Chen, Kuan-Ting
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Lai, Bo-Cheng Charles
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Jou, Jing-Yang
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電子工程學系及電子研究所
Memory Coalescing and on-chip shared Cache are two effective techniques to alleviate the memory bottleneck in modern GPGPUs. These two techniques are very useful on applications with regular memory accesses. However, they become ineffective on concurrent threads with large numbers of uncoordinated accesses and the potential performance benefit could be significantly degraded. This paper proposes a thread affinity mapping methodology to coordinate the irregular data accesses on shared cache GPGPUs. Based on the proposed affinity metrics, threads are congregated into execution groups which are able to fully exploit the memory coalescing and data sharing within an application. An average of 3.5x runtime speedup is achieved on a Fermi GPGPU. The speedup scales with the sizes of test cases, which makes the proposed methodology an effective and promising solution for the continually increasing complexities of applications in the future many-core systems.