著者

Takuma NAKAJIMA Masato YOSHIMI Celimuge WU Tsutomu YOSHINAGA

出版者

The Institute of Electronics, Information and Communication Engineers

雑誌

IEICE TRANSACTIONS on Information and Systems (ISSN:09168532)

巻号頁・発行日

vol.E100-D, no.12, pp.2847-2856, 2017-12-01

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Cooperative caching is a key technique to reduce rapid growing video-on-demand's traffic by aggregating multiple cache storages. Existing strategies periodically calculate a sub-optimal allocation of the content caches in the network. Although such technique could reduce the generated traffic between servers, it comes with the cost of a large computational overhead. This overhead will be the cause of preventing these caches from following the rapid change in the access pattern. In this paper, we propose a light-weight scheme for cooperative caching by grouping contents and servers with color tags. In our proposal, we associate servers and caches through a color tag, with the aim to increase the effective cache capacity by storing different contents among servers. In addition to the color tags, we propose a novel hybrid caching scheme that divides its storage area into colored LFU (Least Frequently Used) and no-color LRU (Least Recently Used) areas. The colored LFU area stores color-matching contents to increase cache hit rate and no-color LRU area follows rapid changes in access patterns by storing popular contents regardless of their tags. On the top of the proposed architecture, we also present a new routing algorithm that takes benefit of the color tags information to reduce the traffic by fetching cached contents from the nearest server. Evaluation results, using a backbone network topology, showed that our color-tag based caching scheme could achieve a performance close to the sub-optimal one obtained with a genetic algorithm calculation, with only a few seconds of computational overhead. Furthermore, the proposed hybrid caching could limit the degradation of hit rate from 13.9% in conventional non-colored LFU, to only 2.3%, which proves the capability of our scheme to follow rapid insertions of new popular contents. Finally, the color-based routing scheme could reduce the traffic by up to 31.9% when compared with the shortest-path routing.

著者

多田 昂介 川原 尚人 吉見 真聡 策力木格 吉永 努 Kousuke Tada Naoto Kawahara Masato Yoshimi Celimuge Wu Tsutomu Yoshinaga

出版者

電子情報通信学会

雑誌

信学技報 (ISSN:09135685)

巻号頁・発行日

vol.116, no.416, pp.37-42, 2017-01

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本研究報告では,ストリームデータの結合処理を行うHandshake Join のFPGA アクセラレータをマルチノードに拡張する手法を提案し,その性能評価を報告する.マルチノード拡張は,データ通信の2 つの工夫によって実現する.FPGA 上に複数のJoin Core を実装すると共に,FPGA ボード上のDRAM を介してFPGA 間でJoin Coreを接続する仕組みを導入する.また,データ通信と結合演算をオーバラップすることで,通信に要するオーバヘッドを隠蔽する.これらのデータ配布方法の工夫により,単一のFPGA では実装できなかった大きなウインドウサイズの結合演算が可能となる.最大16 ノードでの性能評価の結果,マルチノードに拡張した場合においても,結合演算のスループットが維持されるとともに,並列化効果が得られることが確認された.