Operating Systems: Concurrent and Distributed Software Design

27.4. The kernel

Unlike the rest of the executive, the kernel remains resident and runs without preemption, although interrupts from devices will still be delivered. It is written primarily in C with assembly language for those parts which must execute with maximum possible speed or are processor-specific. The kernel has four main functions:

• scheduling threads for execution;

• transferring control to handler routines when interrupts and exceptions occur;

• performing low-level multiprocessor synchronization;

• implementing system recovery procedures after power failure.

Policy/mechanism separation is a design feature of Windows NT and Windows 2000. The kernel provides mechanisms; the executive builds on them and implements policies. Above the kernel, ...