Lightweight remote procedure call

TLDR

LRPC is a lightweight communication facility optimized for same‑machine protection‑domain communication, addressing the high overhead of existing RPC systems that forces designers to merge subsystems and trade safety for performance. The goal of LRPC is to reduce same‑machine communication overhead, thereby enabling both higher safety and performance. LRPC merges the control‑transfer and communication model of capability systems with the programming semantics and large‑grained protection model of RPC. LRPC delivers a three‑fold performance gain over thread‑based message passing, approaching hardware limits, and has been integrated into the Taos OS on the DEC SRC Firefly workstation.

Abstract

Lightweight Remote Procedure Call (LRPC) is a communication facility designed and optimized for communication between protection domains on the same machine. In contemporary small-kernel operating systems, existing RPC systems incur an unnecessarily high cost when used for the type of communication that predominates—between protection domains on the same machine. This cost leads system designers to coalesce weakly related subsystems into the same protection domain, trading safety for performance. By reducing the overhead of same-machine communication, LRPC encourages both safety and performance. LRPC combines the control transfer and communication model of capability systems with the programming semantics and large-grained protection model of RPC. LRPC achieves a factor-of-three performance improvement over more traditional approaches based on independent threads exchanging messages, reducing the cost of same-machine communication to nearly the lower bound imposed by conventional hardware. LRPC has been integrated into the Taos operating system of the DEC SRC Firefly multiprocessor workstation.