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×. 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.
Cite
@article{arxiv.1701.03878,
title = {HoLiSwap: Reducing Wire Energy in L1 Caches},
author = {Yatish Turakhia and Subhasis Das and Tor M. Aamodt and William J. Dally},
journal= {arXiv preprint arXiv:1701.03878},
year = {2017}
}