Repositorio Zaguan - Universidad de Zaragoza 

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000006812 001__ 6812
000006812 037__ $$aTESIS-2012-003
000006812 041__ $$aeng
000006812 1001_ $$aBosque Arbiol, Ana
000006812 24500 $$aFiltering directory lookups in CMPS
000006812 260__ $$aZaragoza$$bUniversidad de Zaragoza, Prensas de la Universidad$$c2011
000006812 300__ $$a98
000006812 490__ $$aTesis de la Universidad de Zaragoza$$v2011-22$$x2254-7606
000006812 500__ $$aPresentado:  11 11 2011
000006812 502__ $$aTesis-Univ. Zaragoza$$bZaragoza, Universidad de Zaragoza$$c2011
000006812 520__ $$aNowadays, most computer manufacturers offer chip multiprocessors (CMPs) due to the always increasing chip density. These CMPs have a broad range of characteristics, but all of them support the shared memory programming model. As a result, every CMP implements a coherence protocol to keep local caches coherent. Coherence protocols consume an important fraction of power to determine which coherence action to perform. Specifically, on CMPs with write-through local caches, a shared cache and a directory-based coherence protocol implemented as a duplicate of local caches tags, we have observed that energy is wasted in the directory due to two main reasons. Firstly, an important fraction of directory lookups are useless, because the target block is not located in any local cache. The power consumed by the directory could be reduce by filtering out useless directory lookups.  Secondly, useful directory lookups (there are local copies of the target block) are performed over target blocks that are shared by a small number of processors. The directory power consumption could be reduced by limiting the directory lookups to only the directory entries that have a copy of the block. Along this thesis we propose two filtering mechanisms. Each of these mechanisms is focused on one of the problems described above: while our first proposal focuses on reducing number of directory lookups performed, our second proposal aims at reducing the associativity of directory lookups. Several implementations of both filtering approaches have been proposed and evaluated, having all of them a very limited hardware complexity. Our results show that the power consumed by the directory can be reduced as much as 30%.
000006812 6531_ $$aArquitectura de ordenadores
000006812 700__ $$aLlabería Griñó, José María$$edir.
000006812 700__ $$aViñals Yúfera, Víctor$$edir.
000006812 700__ $$aIbáñez Marín, Pablo$$edir.
000006812 7102_ $$aUniversidad de Zaragoza$$bInformática e Ingeniería de Sistemas
000006812 8560_ $$fzaguan@unizar.es
000006812 8564_ $$uhttp://zaguan.unizar.es/record/6812/files/TESIS-2012-003.pdf$$zTexto completo (eng)
000006812 909CO $$ooai:zaguan.unizar.es:6812$$pdriver$$ppublic$$pTesis
000006812 909CO $$ptesis
000006812 9102_ $$aArquitectura y tecn. Computadoras$$bInformática e Ingeniería de Sistemas
000006812 980__ $$aTESIS
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