The Case for Thread Migration: Predictable IPC in a Customizable and Reliable OS

Synchronous inter-process communication (IPC) between threads is a popular mechanism for coordination in μ-kernels and component-based operating systems. Significant focus has been placed on its optimization, and consequently the efficiency of practical implementations approaches the lower limits set by hardware. This paper qualitatively compares the predictability properties of the synchronous IPC model with those of the migrating thread model. We assess the idealized communication models, and their practical implementations both in different versions of L4, and in the COMPOSITE component-based OS. We study three main factors – execution accounting, communication end-points, and system customizability – and discuss the trade-offs involved in each model. We make the case that the migrating thread model is as suitable as synchronous IPC, if not more so, in configurable systems requiring strict