  Edge computing has emerged as a popular paradigm for running
latency-sensitive applications due to its ability to offer lower network
latencies to end-users. In this paper, we argue that despite its lower network
latency, the resource-constrained nature of the edge can result in higher
end-to-end latency, especially at higher utilizations, when compared to cloud
data centers. We study this edge performance inversion problem through an
analytic comparison of edge and cloud latencies and analyze conditions under
which the edge can yield worse performance than the cloud. To verify our
analytic results, we conduct a detailed experimental comparison of the edge and
the cloud latencies using a realistic application and real cloud workloads.
Both our analytical and experimental results show that even at moderate
utilizations, the edge queuing delays can offset the benefits of lower network
latencies, and even result in performance inversion where running in the cloud
would provide superior latencies. We finally discuss practical implications of
our results and provide insights into how application designers and service
providers should design edge applications and systems to avoid these pitfalls.
