Data Movement in Kernelized Systems

ions The Mach 3.0 Microkernel and the CHORUS Nucleus supply a similar set of abstractions for building systems servers [10, 17]. Unfortunately, for historical reasons, the two systems often use different names to describe the same thing. The remainder of this section describes the abstractions of Mach 3.0 and CHORUS relevant for understanding the rest of the paper using either the common name or both when necessary. . A Task [4] or Actor [8] is an execution environment and the basic unit of resource allocation. Both include virtual memory and threads. The Mach task also includes port rights. An actor includes ports as communication resources. A task or actor can either be in kernel or user space. . Threads are the basic unit of execution. A task or actor can have multiple simultaneous threads of execution. Threads may communicate via Ports. . Both systems are built around Interprocess Communication or IPC. . Mach ports are protected communication channels [12] managed by the kerne..