A heterogeneous microkernel OS for Rack-Scale systems

Datacenters are adopting heterogeneous hardware in the form of different CPU ISAs and accelerators. Advances in low-latency and high-bandwidth interconnects enable hardware vendors to tighten the coupling of multiple CPU servers and accelerators. The closer connection of components facilitates bigger machines, which pose a new challenge to operating systems. We advocate to build a heterogeneous OS for large heterogeneous systems by combining multiple OS design principles to leverage the benefits of each design. Because a security-oriented design, enabled by simplicity and clear encapsulation, is vital in datacenters, we choose to survey various design principles found in microkernel-based systems. We explain that heterogeneous hardware employs different mechanisms to enforce access rights, for example for memory accesses or communication channels. We outline a way to combine enforcement mechanisms of CPUs and accelerators in one system. A consequence of this is a heterogeneous access rights management which is implemented as a heterogeneous capability system in a microkernel-based OS.