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arXiv · 1701.03878

HoLiSwap: Reducing Wire Energy in L1 Caches

Yatish Turakhia·Subhasis Das·Tor M. Aamodt·William J. Dally
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Abstract

This paper describes HoLiSwap a method to reduce L1 cache wire energy, a significant fraction of total cache energy, by swapping hot lines to the cache way nearest to the processor. We observe that (i) a small fraction (<3%) of cache lines (hot lines) serve over 60% of the L1 cache accesses and (ii) the difference in wire energy between the nearest and farthest cache subarray can be over 6$\times$. Our method exploits this difference in wire energy to dynamically identify hot lines and swap them to the nearest physical way in a set-associative L1 cache. This provides up to 44% improvement in the wire energy (1.82% saving in overall system energy) with no impact on the cache miss rate and 0.13% performance drop. We also show that HoLiSwap can simplify way-prediction.

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Yatish Turakhia, Subhasis Das, Tor M. Aamodt, William J. Dally. 2017-01-14. HoLiSwap: Reducing Wire Energy in L1 Caches. https://arxiv.org/abs/1701.03878

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