  Owing to the characteristics of high density and unlimited write cycles,
skyrmion racetrack memory (SK-RM) has demonstrated great potential as either
the next-generation main memory or the last-level cache of processors with
non-volatility. Nevertheless, the distinct skyrmion manipulations, such as
injecting and shifting, demand a fundamental change in widely-used memory
structures to avoid excessive energy and performance overhead. For instance,
while B{\epsilon}-trees yield an excellent query and insert performance
trade-off between B-trees and Log-Structured Merge (LSM)-trees, the
applicability of deploying B{\epsilon}-trees onto SK-RM receives much less
attention. In addition, even though optimizing designs have been proposed for
B+-trees on SK-RM, those designs are not directly applicable to
B{\epsilon}-trees owing to the batch update behaviors between tree nodes of
B{\epsilon}-trees. Such an observation motivates us to propose the concept of
Sky{\epsilon}-tree to effectively utilize the access port parallelism of SK-RM
to embrace the excellent query and insert performance of B{\epsilon}-trees.
Experimental results have shown promising improvements in access performance
and energy conservation.
