What is a Lightweight Kernel

Lightweight kernels (LWK) have been in use on the compute nodes of supercomputers for decades. Although many high-end systems now run Linux, interest in options and alternatives has increased in the last couple of years. Future extreme-scale systems require rethinking of the operating system, and modern LWKs may well play a role in the final solution. In the course of our research, it has become clear that no single definition for a lightweight kernel exists. This paper describes what we mean by the term and what makes LWKs different from other operating system kernels.