The 28th edition of the Real-Time Networks and Systems Conference (RTNS) was without any doubt very different to previous editions of the conference. The 2020 edition had been planned as an intermediate step in the transition of the conference date from Autumn to Spring. The foreseen venue had been Paris, France. But the travel restriction and the corona pandemic restrictions have put an end to this plan. Instead, RTNS was organized as a purely virtual event. Nevertheless, RTNS 2020 presented 16 papers distributed over four sessions, a session on Real-Time Multicore Systems, on Timing and Monitoring, on Scheduling Systems and on Networked Systems, and a keynote given by Iain Bate from the University of York on “Timing Analysis and Verification of Multi-core Real-Time Systems for Aerospace Applications”.

Papers recognized as outstanding papers from RTNS 2020 were invited to submit extended journal versions for this special issue of the Real-Time Systems Journal. In total, we invited three submissions that are presented in this issue after rigorous peer review by experts from the areas of real-time and networked systems. Two of the submissions investigate multiprocessor/multicore scheduling, although from fundamentally different perspectives and assumptions, the other paper provides a novel cache analysis which is fundamental to the estimation of worst-case execution time bounds.

The first paper in this special issue is “Workload assignment for global real-time scheduling on unrelated multicore platforms” by Antoine Bertout, Joel Goossens, Emmanuel Grolleau and Xavier Poczekajlo. The paper targets task assignment on modern MPSoCs based on a new system model and provides empirical evidence for its practical relevance.

The second paper, “Precise and Efficient Analysis of Context-Sensitive Cache Conflict Sets” by Florian Brandner, provides a novel cache and persistence analysis for classical LRU caches as well as for method caches. The analysis is based on cache summaries, a novel approach to estimating the impact of portions of program code on the cache states.

The third paper, “Scheduling DAGs When Processor Assignments Are Specified” by Sanjoy Baruah, addresses the restricted assignment scheduling problem (RASP). First, the author proves that the scheduling problem is NP-hard in the strong sense, and then proceeds to identify conditions under which the problem can nevertheless be solved efficiently using integer linear programs.

We would like to thank all the authors that submitted their work to the special issue and express appreciation to the referees for their time and effort in selecting and improving the quality of the papers.