|タイトル||P2P VIDEO BROADCAST BASED ON PER-PEER TRANSCODING AND ITS EVALUATION ON PLANETLAB|
Shibata, N., Yasumoto, K., and Mori, M.: P2P Video Broadcast based on Per-Peer Transcoding and its Evaluation on PlanetLab, Proc. of 19th IASTED Int'l. Conf. on Parallel and Distributed Computing and Systems (PDCS2007), pp. 478-483, (November 2007).
We have previously proposed a P2P video broadcast method called MTcast for simultaneously delivering video to user peers with different quality requirements. In this paper, we design and implement a prototype system of MTcast and report the results of its performance evaluation in the real Internet environment. MTcast relies on each peer to transcode and forward video to other peers. We conducted experiments on 20 PlanetLab nodes, evaluated startup delay and recovery time from peer leaving/failure, and confirmed that MTcast achieves practical performance in a real environment.
|タイトル||A Method for Sharing Traffic Jam Information using Inter-Vehicle Communication|
Shibata, N., Terauchi, T., Kitani, T., Yasumoto, K., Ito, M., Higashino, T.:
A Method for Sharing Traffic Jam Information Using Inter-Vehicle Communication, The 2nd International Workshop on Vehicle-to-Vehicle Communications (V2VCOM) (Mobiquitous2006 Workshop), pp. 1-7, DOI:10.1109/MOBIQ.2006.340428 (July 2006) (invited paper).
In this paper, we propose a method for cars to autonomously and cooperatively collect traffic jam statistics to estimate arrival time to destination for each car using inter-vehicle communication. In the method, the target geographical region is divided into areas, and each car measures time to pass through each area. Traffic information is collected by exchanging information between cars using inter-vehicle communication. In order to improve accuracy of estimation, we introduce several mechanisms to avoid same data to be repeatedly counted. Since wireless bandwidth usable for exchanging statistics information is limited, the proposed method includes a mechanism to categorize data, and send important data prior to other data. In order to evaluate effectiveness of the proposed method, we implemented the method on a traffic simulator NETSTREAM developed by Toyota Central R&D Labs, conducted some experiments and confirmed that the method achieves practical performance in sharing traffic jam information using inter-vehicle communication.
|タイトル||Task scheduling algorithm for multicore processor system for minimizing recovery time in case of single node fault|
Shohei Gotoda, Naoki Shibata and Minoru Ito : "Task scheduling algorithm for multicore processor system for minimizing recovery time in case of single node fault," Proceedings of IEEE International Symposium on Cluster Computing and the Grid (CCGrid 2012), pp.260-267, DOI:10.1109/CCGrid.2012.23, May 15, 2012.
In this paper, we propose a task scheduling al-gorithm for a multicore processor system which reduces the recovery time in case of a single fail-stop failure of a multicore processor. Many of the recently developed processors have multiple cores on a single die, so that one failure of a computing node results in failure of many processors. In the case of a failure of a multicore processor, all tasks which have been executed on the failed multicore processor have to be recovered at once. The proposed algorithm is based on an existing checkpointing technique, and we assume that the state is saved when nodes send results to the next node. If a series of computations that depends on former results is executed on a single die, we need to execute all parts of the series of computations again in the case of failure of the processor. The proposed scheduling algorithm tries not to concentrate tasks to processors on a die. We designed our algorithm as a parallel algorithm that achieves O(n) speedup where n is the number of processors. We evaluated our method using simulations and experiments with four PCs. We compared our method with existing scheduling method, and in the simulation, the execution time including recovery time in the case of a node failure is reduced by up to 50% while the overhead in the case of no failure was a few percent in typical scenarios.