269 research outputs found
Precomputing Memory Locations for Parametric Allocations
Get PDFCurrent worst-case execution time (WCET) analyses do not support programs using dynamic memory allocation. This is mainly due to the unpredictability of cache performance introduced by standard memory allocators. To overcome this problem, algorithms have been proposed that precompute static allocations for dynamically allocating programs with known numeric bounds on the number and sizes of allocated memory blocks. In this paper, we present a novel algorithm for computing such static allocations that can cope with parametric bounds on the number and sizes of allocated blocks. To demonstrate the usefulness of our approach, we precompute static allocations or a set of existing real-time applications and academic examples
WCET Analysis for Preemptive Scheduling
Get PDFHard real-time systems induce strict constraints on the timing of the task
set. Validation of these timing constraints is thus a major challenge during the
design of such a system. Whereas the derivation of timing guarantees must
already be considered complex if tasks are running to completion, it gets even
more complex if tasks are scheduled preemptively -- especially due to
caches, deployed to improve the average performance. In this paper we propose
a new method to compute valid upper bounds on a task's worst case execution time
(WCET). Our method approximates an optimal memory layout such that
the set of possibly evicted cache-entries during preemption is
minimized. This set then delivers information to bound the execution time of
tasks under preemption in an adopted WCET analysis
Real-Time System Evaluation Techniques: A Systematic Mapping Study
Get PDFA systematic mapping study assesses a broad selection of research publications with the aim of categorizing them according to a research question. We present the first systematic mapping study on evaluation practices within the field of real-time systems, by analyzing publications from the top three conferences ECRTS, RTAS, and RTSS from 2017 until 2024. Our study provides a comprehensive view on the evaluation practices prevalent in our community, including benchmark software, task set and graph generators, case studies, industrial challenges, and custom solutions.
Based on our study, we construct and publish a dataset enabling quantitative analysis of evaluation practices within the real-time systems community.
Our analysis indicates shortcomings in current practice: custom case studies are abundant, while industrial challenges have very minor impact. Reproducibility has only been shown for a small subset of evaluations and there is no indication of change. Adoption of new and improved tools and benchmarks is very slow or even non-existent.
Evaluation must not be viewed as an obligation when publishing a paper, but as a key element in ensuring practicability, comparability, and reproducibility. Based on our study, we conclude that our community currently falls short on these objectives
Front Matter, Table of Contents, Preface, Conference Organization
No full textFront Matter, Table of Contents, Preface, Conference Organizatio
Cache-Related Preemption Delay Computation for Set-Associative Caches - Pitfalls and Solutions
Get PDFIn preemptive real-time systems, scheduling analyses need - in addition to the worst-case execution time - the context-switch cost. In case of preemption, the preempted and the preempting task may interfere on the cache memory. These interferences lead to additional reloads in the preempted task. The delay due to these reloads is referred to as the cache-related preemption delay (CRPD). The CRPD constitutes a large part of the context-switch cost. In this article, we focus on the computation of upper bounds on the CRPD based on the concepts of useful cache blocks (UCBs) and evicting cache blocks (ECBs). We explain how these concepts can be used to bound the CRPD in case of direct-mapped caches. Then we consider set-associative caches with LRU, FIFO, and PLRU replacement. We show potential pitfalls when using UCBs and ECBs to bound the CRPD in case of LRU and
demonstrate that neither UCBs nor ECBs can be used to bound the CRPD in case of FIFO and PLRU. Finally, we sketch a new approach to circumvent these limitations by using the concept of relative competitiveness
Front Matter - ECRTS 2019 Artifacts, Table of Contents, Preface, Artifact Evaluation Committee
Get PDFFront Matter - ECRTS 2019 Artifacts, Table of Contents, Preface, Artifact Evaluation Committe
- …
