annotate cell.tex @ 8:b70a62630a57

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author gongo
date Tue, 25 Mar 2008 20:45:05 +0900
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1 \section{Cell}
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2 Cell Broadband Engine \cite{cell} は、SCEI と IBM によって開発された
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3 CPU である。2 thread の PPE (PowerPC Processor Element) と、
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4 8 個の SPE (Synergetic Processor Element) を持ち、
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5 EIB と呼ばれる高速リングバスで構成されている。
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6 本研究で用いた PS3Linux (Fedora 8) では、
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7 6 個の SPE を使うことができる (\figref{fig-cbe}) 。
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9 \begin{figure}[tb]
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10 \begin{center}
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11 \includegraphics[scale=0.41]{figure/cbe.pdf}
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12 \caption{Cell Architecture}
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13 \label{fig-cbe}
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14 \end{center}
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15 \end{figure}
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17 SPE には 256KB の Local Store (LS) と呼ばれる、SPE から唯一直接参照できる
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18 メモリ領域があり、バスに負担をかけることなく並列に計算を進めることが出来る。
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19 SPE からメインメモリへは、直接アクセスすることは出来ず、
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20 SPE を構成する一つである MFC (Memory Flow Controller) へ、チャネルを介して
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21 DMA (Direct Memory Access) 命令を送ることで行われる (\figref{fig-cbe-spe}) 。
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22
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23 \begin{figure}[tb]
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24 \begin{center}
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25 \includegraphics[scale=0.6]{figure/cbe-spe.pdf}
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26 \caption{Synergetic Processor Element}
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27 \label{fig-cbe-spe}
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28 \end{center}
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29 \end{figure}
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32 SPE はグラフィックスに適した、4 つの固定小数点、浮動小数点を
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33 同時に演算する命令などを持ち、PPE に比べて高速な演算が可能である。
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34 そのため、ほとんどの演算を SPE 上で行わせることが推奨されている。