Zero-Content Augmented Caches

Julien Dusser 1 Thomas Piquet 1 André Seznec 1
1 CAPS - Compilation, parallel architectures and system
IRISA - Institut de Recherche en Informatique et Systèmes Aléatoires, Inria Rennes – Bretagne Atlantique
Abstract : It has been observed that some applications manipulate large amounts of null data. Moreover these zero data often exhibit high spatial locality. On some applications more than 20% of the data accesses concern null data blocks. Representing a null block in a cache on a standard cache line is clearly a waste of resources. In this paper, we propose the Zero-Content Augmented cache, the ZCA cache. A ZCA cache consists of a conventional cache augmented with a specialized cache for memorizing null blocks, the Zero-Content cache or ZC cache. In the ZC cache, the data block is represented by its address tag and a validity bit. Moreover, as null blocks generally exhibit high spatial locality, several null blocks can be associated with a single address tag in the ZC cache. For instance, a ZC cache mapping 32MB of zero 64-byte lines uses less than 80KB of storage. Decompression of a null block is very simple, therefore read access time on the ZCA cache is in the same range as on a conventional cache. On applications manipulating large amount of null data blocks, such a ZC cache allows to reduce up to 81% the miss rate and memory traffic, and therefore to increase performance for a small hardware overhead. In particular, the writeback traffic on null blocks is limited. For applications with a low null block rate no performance loss is observed.
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Rapport
[Research Report] RR-6705, INRIA. 2008
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https://hal.inria.fr/inria-00337742
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Soumis le : vendredi 7 novembre 2008 - 18:34:28
Dernière modification le : jeudi 15 novembre 2018 - 11:57:03
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  • HAL Id : inria-00337742, version 1

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Julien Dusser, Thomas Piquet, André Seznec. Zero-Content Augmented Caches. [Research Report] RR-6705, INRIA. 2008. 〈inria-00337742〉

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