We consider the problem of scheduling a set of preemptible independent periodic implicit-deadline hard real- time tasks on heterogeneous processors. We divide this problem into two sub-problems: (a) assigning portions of each proces- sor (offline) to each task without jeopardizing schedulability; and (b) generating a schedule satisfying the assigned portions using an online semi-partitioned scheduler, called Heterogeneous Quasi-Partitioned Scheduling (hQPS). The scheduler handles task servers at run-time for ensuring that the processor shares assigned to tasks are timely available to them. Assessments indicate that the proposed solution (i) has good scalability (up to 64 tasks, 64 processors), (ii) is effective in generating schedules with few preemptions and few migrations, and (iii) is effective in managing resources; for task sets where an extra processor speed is required, our solution needs at most 10% extra compared to an optimal scheduler.

Heterogeneous Quasi-Partitioned Scheduling

This paper presents a task synchronization mechanism, called co-runner locking, to address the timing interference problem in multi-core real-time systems. It prevents certain subsets of tasks from executing simultaneously on different cores in order to avoid large performance penalties from inter-core interference. We provide the general properties of the co-runner locking mechanism and discuss the runtime control policies that determine the execution order of tasks in a co-runner locking relationship. For schedulability analysis, we derive a response-time test that upper-bounds the delay from co-runner locking and the slowdown imposed by permitted co-runners by combining two new analytic approaches: job-oriented and load-oriented. In evaluation, we demonstrate that the co-runner locking mechanism is an effective alternative to address the “one out-of-m” problem and brings about a significant improvement in real-time taskset schedulability.

Addressing Multi-Core Timing Interference using Co-Runner Locking

In this paper we present a new scheduling model for resilient real-time mixed trust systems. This model extends the previous Real-Time Mixed-Trust Computing framework RT-MTC to support degradation modes. Management of these modes has been identified in industrial documents as a key requirement for deploying trusted autonomous vehicles for safe autonomy. RT-MTC uses verified components (known as enforcers) to guarantee that the output of a system is safe by replacing it with a verified safe one if this output is deemed unsafe or is not produced on time. In this paper we extend RT-MTC and develop a scheduling model that uses the digraph scheduling model as a baseline but extends it in four critical ways: (1) it creates extensions for the mixed-preemptive scheduling required by RT-MTC, (2) it enables priority bands in order to separate trusted and untrusted components, (3) it uses these bands in order to calculate intermediate deadlines used by the RT-MTC framework for the scheduling of the trusted components, and (4) it defines system mode semantics to obtain two desirable properties of the new schedulability analysis: low pessimism and low time-complexity. This paper evaluates the new schedulability algorithm and shows that it is efficient in that it only needs to analyze one transition at a time. The new model supports the construction of a resilient autonomous system with provable guarantees protected by verified enforcers within the RT-MTC framework and, more importantly, preserves these guarantees even across failure-triggered mode changes.

Resilient Mixed-Trust Scheduling

**Session chair:** Paolo Pazzaglia<br><br>

- 25 min: [**Suspension-Aware Fixed-Priority Schedulability Test with Arbitrary Deadlines And Arrival Curves**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a418/280200a418.pdf), *Mario Guenzel, Niklas Ueter and Jian-Jia Chen*
- 25 min: [**(Outstanding Paper) TORTIS: Retry-Free Software Transactional Memory for Real-Time Systems**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a469/280200a469.pdf), *Claire Nord, Shai Caspin, Catherine Nemitz, Howard Shrobe, Hamed Okhravi, Jim Anderson, Nathan Burow and Bryan Ward*
- 25 min: [**Tighter Bounds of Speedup Factor of Partitioned EDF for Constrained-Deadline Sporadic Tasks**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a431/280200a431.pdf), *Xingwu Liu, Zizhao Chen, xin han, Zhenyu Sun and Zhishan Guo*
- 25 min: [**Heterogeneous Quasi-Partitioned Scheduling**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a266/280200a266.pdf), *Ernesto Massa, George Lima, Bjorn Andersson and Vinicius Petrucci*



2.13 - Scheduling II

technical paper

 **RTSS 2021** has successfully concluded. Hope you have enjoyed it, and look forward to seeing you next year in person.
    Announcement for the Awards:
 * Best Paper Award goes to: Monte Carlo Response-Time Analysis, Sergey Bozhko, Georg von der Brüggen, and Björn Brandenburg
 * Best Student Paper Award goes to: Automatic Energy-Hotspot Detection and Elimination in Real-Time Deeply Embedded Systems, Mohsen Shekarisaz, Lothar Thiele, and Mehdi Kargahi.
 * Best Solution Award for Industry Session goes to: Toward Real-Time Guaranteed Scheduling for Autonomous Driving Systems. Jinghao Sun, Tianyi Wang, Kailu Duan, Bin Lu, Jiankang Ren, Zhishan Guo, and Guozhen Tan.



IEEE RTSS 2021

The IEEE Real-Time Systems Symposium (RTSS) is the premier conference in the field of real-time systems, and is a venue for researchers and practitioners to showcase innovations covering all aspects of real-time systems, including theory, design, analysis, implementation, evaluation, and experience. 

 **Session chair:** Steffen Bondorf <br><br>

- 25 min: [**Response-Time Analysis and Optimization for Probabilistic Conditional Parallel DAG Tasks**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a380/280200a380.pdf), *Niklas Ueter, Mario Guenzel and Jian-Jia Chen*
- 25 min: [**A ROS 2 Response-Time Analysis Exploiting Starvation Freedom and Execution-Time Variance (Artifact Evaluated)**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a041/280200a041.pdf), *Tobias Blass, Daniel Casini, Sergey Bozhko and Björn Brandenburg*
- 25 min: [**Addressing Multi-Core Timing Interference using Co-Runner Locking**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a054/280200a054.pdf), *Hyoseung Kim, Dionisio de Niz, Bjorn Andersson, Mark Klein and John Lehoczky*
- 25 min: [**(Outstanding Paper) Monte Carlo Response-Time Analysis**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a342/280200a342.pdf), *Sergey Bozhko, Georg von der Brüggen and Björn Brandenburg*




3.12 - Response Time and Interference Analysis

**Session chair:** Jan Reineke

- 25 min: [**Cluster-based Network Time Synchronization for Resilience with Energy Efficiency (Artifact Evaluated)**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a149/280200a149.pdf), *Nitin Shivaraman, Patrick Schuster, Saravanan Ramanathan, Arvind Easwaran and Sebastian Steinhorst*
- 25 min: [**A middleware protocol for time-critical wireless communication of large data samples (Artifact Evaluated)**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a001/280200a001.pdf), *Jonas Peeck, Mischa Möstl, Tasuku Ishigooka and Rolf Ernst*
- 25 min: [**Enumeration and Deduction Driven Co-Synthesis of CCSL Specifications Using Reinforcement Learning (Artifact Evaluated)**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a227/280200a227.pdf), *Ming Hu, Jiepin Ding, Min Zhang, Frederic Mallet and Mingsong Chen*
- 25 min: [**Resilient Mixed-Trust Scheduling**](https://conferences.computer.org/rtsspub/pdfs/RTSS2021-23beZleJJDdiozCiQ9rzXD/280200a368/280200a368.pdf), *Dionisio de Niz, Bjorn Andersson, Hyoseung Kim, Mark Klein and John Lehoczky*



Bjorn Andersson

3

1

SHORT BIO

Presentations

Heterogeneous Quasi-Partitioned Scheduling

Addressing Multi-Core Timing Interference using Co-Runner Locking

Resilient Mixed-Trust Scheduling