  The number and diversity of consumer devices are growing rapidly, alongside
their target applications' memory consumption. Unfortunately, DRAM scalability
is becoming a limiting factor to the available memory capacity in consumer
devices. As a potential solution, manufacturers have introduced emerging
non-volatile memories (NVMs) into the market, which can be used to increase the
memory capacity of consumer devices by augmenting or replacing DRAM. Since
entirely replacing DRAM with NVM in consumer devices imposes large system
integration and design challenges, recent works propose extending the total
main memory space available to applications by using NVM as swap space for
DRAM. However, no prior work analyzes the implications of enabling a real
NVM-based swap space in real consumer devices.
  In this work, we provide the first analysis of the impact of extending the
main memory space of consumer devices using off-the-shelf NVMs. We extensively
examine system performance and energy consumption when the NVM device is used
as swap space for DRAM main memory to effectively extend the main memory
capacity. For our analyses, we equip real web-based Chromebook computers with
the Intel Optane SSD, which is a state-of-the-art low-latency NVM-based SSD
device. We compare the performance and energy consumption of interactive
workloads running on our Chromebook with NVM-based swap space, where the Intel
Optane SSD capacity is used as swap space to extend main memory capacity,
against two state-of-the-art systems: (i) a baseline system with double the
amount of DRAM than the system with the NVM-based swap space; and (ii) a system
where the Intel Optane SSD is naively replaced with a state-of-the-art (yet
slower) off-the-shelf NAND-flash-based SSD, which we use as a swap space of
equivalent size as the NVM-based swap space.
