  HPC and Cloud have evolved independently, specializing their innovations into
performance or productivity. Acceleration as a Service (XaaS) is a recipe to
empower both fields with a shared execution platform that provides transparent
access to computing resources, regardless of the underlying cloud or HPC
service provider. Bridging HPC and cloud advancements, XaaS presents a unified
architecture built on performance-portable containers. Our converged model
concentrates on low-overhead, high-performance communication and computing,
targeting resource-intensive workloads from climate simulations to machine
learning. XaaS lifts the restricted allocation model of Function-as-a-Service
(FaaS), allowing users to benefit from the flexibility and efficient resource
utilization of serverless while supporting long-running and
performance-sensitive workloads from HPC.
