The Performance of u-Kernel-Based Systems

Question

Q: Compare and contrast the L4 microkernel with Nucleus and Hydra in terms of their goals to provide a basis on which higher-level OS functionality can be implemented.

Background

u-kernels or micro kernels - kernels that provide only address spaces, threads and IPCs or an equivalent set of primitives.

• Previous work theorize that the lack of hardware implementations force increased software abstractions on top of u-kernels leading to lower performance

L4 u-kernel

Based on two basic concepts:

• Threads - execution inside an address space
• Address space
  • L4 supports “recursive construction” of address spaces
    • In other words, an owner of an address space can grant a subset of its pages to another address space as long as the recipient agrees Pagers -