The Synthesis Kernel

The Synthesis distributed operating system combines efficient kernel calls with a highlevel, orthogonal interface. The key concept is the use ofa code synthesizer in the kernel to generate specialized (thus short and fast) kernel routines for specifrc situations. We have three methods of synthesizing code: Factoring Invariants to bypass redundant computations; Collapsing Layers to eliminate unnecessary procedure calls and context switches; and Executable Data Structures to shorten data structure traversal time. Applying these methods, the kernel call synthesized to read /dev/mem takes about l5 microseconds on a 6g020 machine. A simple model of computation called a synthetic machine supports parallel and distributed processing. The interface to synthetic machine consists of six operations on four kinds of objects. This combination of a high-level interface with the code synthesizer avoids the traditional trade-off in operating systems between powerful interfaces and efrcient implementations. @ Computíng Systems, Vol. I . No. I . Winter 1988 11