# Boomerang: Real-Time I/O Meets Legacy Systems

## TL;DR

Boomerang is a hybrid I/O system that combines a small real-time OS with a legacy system to provide predictable, end-to-end processing delays for timing-critical tasks, outperforming traditional Linux and virtualization solutions.

## Contribution

This paper introduces Boomerang, a novel system that integrates a legacy OS with a real-time OS to ensure predictable I/O performance and end-to-end timing guarantees.

## Key findings

- Boomerang guarantees end-to-end processing delays within specified time bounds.
- It outperforms standalone Linux with deadline-based CPU reservations.
- It surpasses the virtualized ACRN system in automotive contexts.

## Abstract

This paper presents Boomerang, an I/O system that integrates a legacy non-real-time OS with one that is customized for timing-sensitive tasks. A relatively small RTOS benefits from the pre-existing libraries, drivers and services of the legacy system. Additionally, timing-critical tasks are isolated from less critical tasks by securely partitioning machine resources among the separate OSes. Boomerang guarantees end-to-end processing delays on input data that requires outputs to be generated within specific time bounds. We show how to construct composable task pipelines in Boomerang that combine functionality spanning a custom RTOS and a legacy Linux system. By dedicating time-critical I/O to the RTOS, we ensure that complementary services provided by Linux are sufficiently predictable to meet end-to-end service guarantees. While Boomerang benefits from spatial isolation, it also outperforms a standalone Linux system using deadline-based CPU reservations for pipeline tasks. We also show how Boomerang outperforms a virtualized system called ACRN, designed for automotive systems.