6812 20190219123700.0 TESIS-2012-003 eng Bosque Arbiol, Ana Filtering directory lookups in CMPS Zaragoza Universidad de Zaragoza, Prensas de la Universidad 2011 98 Tesis de la Universidad de Zaragoza 2011-22 2254-7606 Presentado: 11 11 2011 Tesis-Univ. Zaragoza Zaragoza, Universidad de Zaragoza 2011 by-nc-nd Creative Commons 3.0 https://creativecommons.org/licenses/by-nc-nd/3.0/ Nowadays, 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%. Arquitectura de ordenadores Llabería Griñó, José María dir. Viñals Yúfera, Víctor dir. Ibáñez Marín, Pablo dir. Universidad de Zaragoza Informática e Ingeniería de Sistemas zaguan@unizar.es 10364953 http://zaguan.unizar.es/record/6812/files/TESIS-2012-003.pdf Texto completo (eng) oai:zaguan.unizar.es:6812 tesis driver Arquitectura y tecn. Computadoras Informática e Ingeniería de Sistemas TESIS