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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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Submitted on : Friday, November 7, 2008 - 6:34:28 PM
Last modification on : Friday, February 4, 2022 - 3:15:34 AM
Long-term archiving on: : Tuesday, June 28, 2011 - 5:40:58 PM


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  • HAL Id : inria-00337742, version 1


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



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