Supporting Read/Write Applications in Embedded Real-time Systems via Suspension-aware Analysis

TL;DR

This paper introduces new analysis and scheduling techniques for embedded real-time systems to effectively handle suspension delays caused by I/O operations, significantly improving system utilization.

Contribution

It proposes a suspension-aware analysis for write-only applications and a novel I/O placement and scheduling strategy for read-write applications, reducing pessimism and suspension impact.

Findings

Improved analysis reduces suspension-related utilization loss to O(m).

I/O placement strategy circumvents suspension delays.

Experiments show significant utilization improvements.

Abstract

In many embedded real-time systems, applications often interact with I/O devices via read/write operations, which may incur considerable suspension delays. Unfortunately, prior analysis methods for validating timing correctness in embedded systems become quite pessimistic when suspension delays are present. In this paper, we consider the problem of supporting two common types of I/O applications in a multiprocessor system, that is, write-only applications and read-write applications. For the write-only application model, we present a much improved analysis technique that results in only O(m) suspension-related utilization loss, where m is the number of processors. For the second application model, we present a flexible I/O placement strategy and a corresponding new scheduling algorithm, which can completely circumvent the negative impact due to read- and write-induced suspension delays. We illustrate the feasibility of the proposed I/O-placement-based schedule via a case study implementation. Furthermore, experiments presented herein show that the improvement with respect to system utilization over prior methods is often significant.