PULC: ParaStation User-Level Communication. Design and Overview

PULC is a user-level communication library for workstation clusters. PULC provides a multi-user, multi-programming communication library for user level communication on top of high-speed communication hardware. In this paper, we describe the design of the communication subsystem, a rst implementation on top of the ParaStation communication card, and benchmark results of this rst implementation. PULC removes the operating system from the communication path and o ers a multi-process environment with user-space communication. Additionally, we have moved some operating system functionality to the user level to provide higher e ciency and exibility. Message demultiplexing, protocol processing, hardware interfacing, and mutual exclusion of critical sections are all implemented in user-level. PULC o ers the programmer multiple interfaces including TCP user-level sockets, MPI [CGH94], PVM [BDG93], and Active Messages [CCHvE96]. Throughput and latency are close to the hardware performance (e.g., the TCP socket protocol has a latency of less than 9 s).