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In this paper we consider the<italic>k</italic>-clustering problem for a set <italic>S</italic> of <italic>n</italic> points <inline-equation><f><inf>i</inf>=<fen lp="par"><b>x<inf>i</inf></b><rp post="par"> </fen></f> </inline-equation> in the<italic>d</italic>-dimensional space with variance-based errors as clustering criteria, motivated from the color(More)
We describe the GRAPE-DR (Greatly Reduced Array of Processor Elements with Data Reduction) system, which will consist of 4096 processor chips each with 512 cores operating at the clock frequency of 500 MHz. The peak speed of a processor chip is 512Gflops (single precision) or 256 Gflops (double precision). The GRAPE-DR chip works as an attached processor(More)
As the network speed grows, inter-layer coordination becomes more important. This paper shows 3 inter-layer coordination methods; (1) "Comet-TCP"; cooperation of data-link layer and transport layer using hardware, (2) "Transmission Rate Controlled TCP (TRC-TCP)"; cooperation of data-link layer and transport layer using software, and (3) "Dulling Edges of(More)
End-to-end communications on 10 Gigabit Ethernet (10GbE) WAN became popular. However, there are difficulties that need to be solved before utilizing Long Fat-pipe Networks (LFNs) by using TCP. We observed that the followings caused performance depression: short-term bursty data transfer, mismatch between TCP and hardware support, and excess CPU load. In(More)
This paper describes computational results for k-clustering algorithm using random sampling technique [2] to show its practical usefulness. By computational experiments, first, we show that small size of samples are actually enough for 2-clustering problem. Then, we apply this algorithm for k-clustering problem in a recursive manner and use the output as(More)
Hardware data prefetching is widely adopted to hide long memory latency. A hardware data prefetcher predicts the memory address that will be accessed in the near future and fetches the data at the predicted address into the cache memory in advance. To detect memory access patterns such as a constant stride, most existing prefetchers use differences between(More)
We propose data sharing facility for data intensive scientific research, "Data Reservoir"; which is optimized to transfer huge amount of data files between distant places fully utilizing multi-gigabit backbone network. In addition, "Data Reservoir" can be used as an ordinary UNIX server in local network without any modification of server softwares. We use(More)