  Spin-Transfer Torque RAMs (STTRAMs) have been shown to offer much promise for
implementing emerging cache architectures. This paper studies the viability of
STTRAM caches for mobile workloads from the perspective of energy and latency.
Specifically, we explore the benefits of reduced retention STTRAM caches for
mobile applications. We analyze the characteristics of mobile applications'
cache blocks and how those characteristics dictate the appropriate retention
time for mobile device caches. We show that due to their inherently interactive
nature, mobile applications' execution characteristics---and hence, STTRAM
cache design requirements---differ from other kinds of applications. We also
explore various STTRAM cache designs in both single and multicore systems, and
at different cache levels, that can efficiently satisfy mobile applications'
execution requirements, in order to maximize energy savings without introducing
substantial latency overhead.
