  Huge energy consumption poses a significant challenge for edge clouds. In
response to this, we introduce a new type of edge server, namely SoC Cluster,
that orchestrates multiple low-power mobile system-on-chips (SoCs) through an
on-chip network. For the first time, we have developed a concrete SoC Cluster
consisting of 60 Qualcomm Snapdragon 865 SoCs housed in a 2U rack, which has
been successfully commercialized and extensively deployed in edge clouds. Cloud
gaming emerges as the principal workload on these deployed SoC Clusters, owing
to the compatibility between mobile SoCs and native mobile games.
  In this study, we aim to demystify whether the SoC Cluster can efficiently
serve more generalized, typical edge workloads. Therefore, we developed a
benchmark suite that employs state-of-the-art libraries for two critical edge
workloads, i.e., video transcoding and deep learning inference. This suite
evaluates throughput, latency, power consumption, and other
application-specific metrics like video quality. Following this, we conducted a
thorough measurement study and directly compared the SoC Cluster with
traditional edge servers, with regards to electricity usage and monetary cost.
Our results quantitatively reveal when and for which applications mobile SoCs
exhibit higher energy efficiency than traditional servers, as well as their
ability to proportionally scale power consumption with fluctuating incoming
loads. These outcomes provide insightful implications and offer valuable
direction for further refinement of the SoC Cluster to facilitate its
deployment across wider edge scenarios.
