@article { ChenTC2018,
  author = {Chen, Kuan-Hsun and Br\"uggen, Georg von der and Chen, Jian-Jia},
  title = {Reliability Optimization on Multi-Core Systems with Multi-Tasking and Redundant Multi-Threading},
  journal = {IEEE Transactions on Computers},
  year = {2018},
  note = {10.1109/TC.2017.2769044},
  url = {http://ieeexplore.ieee.org/abstract/document/8094023/},
  keywords = {kuan, georg},
  confidential = {n},
  abstract = {Using Redundant Multithreading (RMT) for error detection and recovery is a prominent technique to mitigate soft-error effects in multi-core systems. Simultaneous Redundant Threading (SRT) on the same core or Chip-level Redundant Multithreading (CRT) on different cores can be adopted to implement RMT. However, only a few previously proposed approaches use adaptive CRT managements on the system level and none of them considers both SRT and CRT on the task level. In this paper, we propose to use a combination of SRT and CRT, called Mixed Redundant Threading (MRT), as an additional option on the task level. In our coarse-grained approach, we consider SRT, CRT, and MRT on the system level simultaneously, while the existing results only apply either SRT or CRT on the system level, but not simultaneously. In addition, we consider further fine-grained task level optimizations to improve the system reliability under hard real-time constraints. To optimize the system reliability, we develop several dynamic programming approaches to select the redundancy levels under Federated Scheduling. The simulation results illustrate that our approaches can significantly increase the system reliability compared to the state-of-the-art techniques.},
}

@inproceedings { dong2018rtas,
  author = {Dong, Zheng and Liu, Cong and Bateni, Soroush and Chen, Kuan-Hsun and Chen, Jian-Jia and Br\"uggen, Georg von der and Shi, Junjie},
  title = {Shared-Resource-Centric Limited Preemptive Scheduling: A Comprehensive Study of Suspension-based Partitioning Approaches},
  booktitle = {IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS)},
  year = {2018},
  keywords = {kuan, georg},
  confidential = {n},
  abstract = {This paper studies the problem of scheduling a set of hard real-time sporadic tasks that may access CPU cores and
a shared resource. Motivated by the observation that the CPU resource is often abundant compared to the shared resources in multi-core and many-core systems, we propose to resolve this problem from a counter-intuitive shared-resource-centric perspective, focusing on judiciously prioritizing and scheduling tasks’ requests in a limited preemptive manner on the shared resource while viewing the worst-case latency a task may experience on the CPU cores as suspension delays. We develop a rather comprehensive set of task partitioning algorithms that partition tasks onto the shared resource with the objective of guaranteeing schedulability while minimizing the required size of the shared resource, which plays a critical role in reducing the overall cost and complexity of building resource-constrained embedded systems in many application domains. A GPU-based prototype case study and extensive simulation-based experiments have been conducted, which validate both our shared-resource-centric scheduling philosophy and the efficiency of our suspension-based partitioning solutions in practice. },
}

@inproceedings { DBLP:conf/ecrts/ChenBHD17,
  author = {Chen, Jian-Jia and Br\"uggen, Georg von der and Huang, Wen-Hung and Davis, Robert I.},
  title = {On the Pitfalls of Resource Augmentation Factors and Utilization Bounds in Real-Time Scheduling},
  booktitle = {29th Euromicro Conference on Real-Time Systems, {ECRTS}},
  year = {2017},
  pages = {9:1--9:25},
  address = {Dubrovnik, Croatia},
  month = {June 27-30},
  url = {https://doi.org/10.4230/LIPIcs.ECRTS.2017.9},
  keywords = {Georg},
  file = {http://drops.dagstuhl.de/opus/volltexte/2017/7161/pdf/LIPIcs-ECRTS-2017-9.pdf},
  confidential = {n},
}

@inproceedings { DBLP:conf/rtcsa/ChenBH017,
  author = {Chen, Jian-Jia and Br\"uggen, Georg von der and Huang, Wen-Hung and Liu, Cong},
  title = {State of the art for scheduling and analyzing self-suspending sporadic real-time tasks},
  booktitle = {23rd {IEEE} International Conference on Embedded and Real-Time Computing Systems and Applications {RTCSA} },
  year = {2017},
  pages = {1--10},
  address = {Hsinchu, Taiwan},
  month = {August 16-18},
  note = {Invited paper},
  url = {http://doi.ieeecomputersociety.org/10.1109/RTCSA.2017.8046321},
  keywords = {Georg},
  file = {media/documents/publications/downloads/2017-chen-RTCSA.suspension-review.pdf},
  confidential = {n},
}

@inproceedings { DBLP:conf/rtcsa/BruggenHC17,
  author = {Br\"uggen, Georg von der and Huang, Wen-Hung and Chen, Jian-Jia},
  title = {Hybrid self-suspension models in real-time embedded systems},
  booktitle = {23rd {IEEE} International Conference on Embedded and Real-Time Computing Systems and Applications, {RTCSA} },
  year = {2017},
  pages = {1--9},
  address = {Hsinchu, Taiwan},
  month = {August 16-18},
  url = {http://doi.ieeecomputersociety.org/10.1109/RTCSA.2017.8046328},
  keywords = {Georg, kevin},
  file = {media/documents/publications/downloads/2017-vdbruggen-RTCSA-hybrid-suspension.pdf},
  confidential = {n},
}

@inproceedings { DBLP:conf/rtns/Bruggen17rop,
  author = {Br\"uggen, Georg von der and Chen, Jian-Jia and Huang, Wen-Hung and Yang, Maolin},
  title = {Release Enforcement in Resource-Oriented Partitioned Scheduling for Multiprocessor Systems},
  booktitle = {25th International Conference on Real-Time Networks and Systems (RTNS)},
  year = {2017},
  keywords = {Georg, kevin},
  file = {http://ls12-www.cs.tu-dortmund.de/daes/media/documents/publications/downloads/2017_rtns_brueggen_rop.pdf},
  confidential = {n},
}

@inproceedings { DBLP:conf/rtns/Bruggen17automotive,
  author = {Br\"uggen, Georg von der and Ueter, Niklas and Chen, Jian-Jia and Freier, Matthias},
  title = {Parametric Utilization Bounds for Implicit-Deadline Periodic Tasks in Automotive Systems},
  booktitle = {25th International Conference on Real-Time Networks and Systems (RTNS)},
  year = {2017},
  address = {Grenoble, France},
  keywords = {Georg},
  file = {http://ls12-www.cs.tu-dortmund.de/daes/media/documents/publications/downloads/2017_brueggen_rtns_automotive.pdf},
  confidential = {n},
}

@techreport { ChenReport854-2016,
  author = {Chen, Jian-Jia and Nelissen, Geoffrey and Huang, Wen-Hung and Yang, Maolin and Brandenburg, Bj\"orn and Bletsas, Konstantinos and Liu, Cong and Richard, Pascal and Ridouard, Fr\'ed\'eric and Audsley, Neil and Rajkumar, Raj and Niz, Dionisio and Br\"uggen, Georg von der},
  title = {Many Suspensions, Many Problems: A Review of Self-Suspending Tasks in Real-Time Systems},
  institution = {Department of Computer Science, TU Dortmund},
  year = {2017},
  number = {854},
  month = {March},
  note = { (Status: Preprint, 2nd Version)   The  first version  was published in May 2016.},
  keywords = {kevin, Georg},
  file = {http://ls12-www.cs.tu-dortmund.de/daes/media/documents/publications/downloads/2017-chen-techreport-854-v2.pdf},
  confidential = {n},
  abstract = {In general computing systems, a job (process/task) may suspend itself whilst it is waiting for some activity to complete, e.g., an accelerator to return data. % or results from offloaded computation. In real-time systems, such self-suspension can cause substantial performance/schedulability degradation. This observation, first made in 1988, has led to the investigation of the impact of self-suspension on timing predictability, and many relevant results have been published since. Unfortunately, as it has recently come to light, a number of the existing results are flawed.

To provide a correct platform on which future research can be built, this paper reviews the state of the art in the design and analysis of scheduling algorithms and schedulability tests for self-suspending tasks in real-time systems.  We provide (1)~a systematic description of how self-suspending tasks can be handled in both soft and hard real-time systems; (2)~an explanation of the existing misconceptions  and their potential remedies; (3)~an assessment of the influence of  such flawed analyses on partitioned multiprocessor fixed-priority scheduling when tasks synchronize access to shared resources; and (4)~a discussion of the computational complexity of analyses for different self-suspension task models.
},
}

@article { IPL2017-speedup,
  author = {Br\"uggen, Georg von der and Chen, Jian-Jia and Davis, Robert I. and Huang, Wen-Hung Kevin},
  title = {Exact Speedup Factors for Linear-Time Schedulability Tests for Fixed-Priority Preemptive and Non-preemptive Scheduling},
  journal = {Information Processing Letters (IPL)},
  year = {2017},
  volume = {117},
  pages = {1-5},
  month = {Jan},
  url = {http://dx.doi.org/10.1016/j.ipl.2016.08.001},
  keywords = {kevin, Georg},
  file = {http://ls12-www.cs.tu-dortmund.de/daes/media/documents/publications/downloads/2016-IPL-speedup.pdf},
  confidential = {n},
  abstract = {In this paper, we investigate the quality of several linear-time schedulability tests for preemptive and non-preemptive fixed-priority scheduling of uniprocessor systems. The metric used to assess the quality of these tests is the resource augmentation bound commonly known as the processor speedup factor. The speedup factor of a schedulability test corresponds to the smallest factor by which the processing speed of a uniprocessor needs to be increased such that any task set that is feasible under an optimal preemptive (non-preemptive) work-conserving scheduling algorithm is guaranteed to be schedulable with preemptive (non-preemptive) fixed priority scheduling if this scheduling test is used, assuming an appropriate priority assignment. We show the surprising result that the exact speedup factors for Deadline Monotonic (DM) priority assignment combined with sufficient linear-time schedulability tests for implicit-, constrained-, and arbitrary-deadline task sets are the same as those obtained for optimal priority assignment policies combined with exact schedulability tests. Thus in terms of the speedup-factors required, there is no penalty in using DM priority assignment and simple linear schedulability tests.
},
}

@inproceedings { WMC2016,
  author = {Chen, Kuan-Hsun and Br\"uggen, Georg von der and Chen, Jian-Jia},
  title = {Overrun Handling for Mixed-Criticality Support in RTEMS},
  booktitle = {Workshop on Mixed-Criticality Systems},
  year = {2016},
  keywords = {kuan, Georg},
  file = {http://ls12-www.cs.tu-dortmund.de/daes/media/documents/publications/downloads/2016-wmc.pdf},
  confidential = {n},
  abstract = {Real-time operating systems are not only used in embedded real-time systems but also useful for the simulation and
validation of those systems. During the evaluation of our paper about Systems with Dynamic Real-Time Guarantees that appears in RTSS 2016 we discovered certain unexpected system behavior in the open-source real-time operating system RTEMS. In the current implementation of RTEMS (version 4.11), overruns of an implicit-deadline task, i.e., deadline misses, result in unexpected system behavior as they may lead to a shift of the release pattern of the task. This also has the consequence that some task instances are not released as they should be. In this paper we explain the reason why such problems occur in RTEMS and our solutions.},
}

@inproceedings { RTSS2016-dynamic-faulty,
  author = {Br\"uggen, Georg von der and Chen, Kuan-Hsun and Huang, Wen-Hung and Chen, Jian-Jia},
  title = {Systems with Dynamic Real-Time Guarantees in Uncertain and Faulty Execution Environments},
  booktitle = {Real-Time Systems Symposium (RTSS)},
  year = {2016},
  address = {Porto, Portugal},
  month = {Nov. 29 - Dec. 2},
  keywords = {georg, kevin, kuan},
  file = {http://ls12-www.cs.tu-dortmund.de/daes/media/documents/publications/downloads/mixed_critical.pdf},
  confidential = {n},
}

@inproceedings { vonderBruggen:2016:USS:2997465.2997497,
  author = {Br\"uggen, Georg von der and Huang, Wen-Hung and Chen, Jian-Jia and Liu, Cong},
  title = {Uniprocessor Scheduling Strategies for Self-Suspending Task Systems},
  booktitle = {Proceedings of the 24th International Conference on Real-Time Networks and Systems (RTNS)},
  year = {2016},
  pages = {119--128},
  month = {October},
  publisher = {ACM},
  url = {http://dl.acm.org/ft_gateway.cfm?id=2997497\&ftid=1804918\&dwn=1\&CFID=691780547\&CFTOKEN=64912419},
  keywords = {georg, kevin},
  file = {http://dl.acm.org/ft_gateway.cfm?id=2997497\&ftid=1804918\&dwn=1\&CFID=691780547\&CFTOKEN=64912419},
  confidential = {n},
  abstract = {(open access)},
}

@inproceedings { brueggen:2015:ecrts,
  author = {Br\"uggen, Georg von der and Chen, Jian-Jia and Huang, Wen-Hung},
  title = {Schedulability and Optimization Analysis for Non-Preemptive Static Priority Scheduling Based on Task Utilization and Blocking Factors},
  booktitle = {Proceedings of Euromicro Conference on Real-Time Systems (ECRTS)},
  year = {2015},
  address = {Lund, Sweden},
  month = {July 8-10},
  note = {We identified an error and revised the paper on Aug. 14th 2015.  Short summary of erratum },
  keywords = {georg, kevin},
  file = {http://ls12-www.cs.tu-dortmund.de/daes/media/documents/publications/downloads/2015_brueggen_ecrts.pdf},
  confidential = {n},
  abstract = {For real time task sets, allowing preemption is often considered to be 
important to ensure the schedulability, as it allows high-priority tasks
to be allocated to the processor nearly immediately.
However, preemptive scheduling also introduces some additional
overhead and may not be allowed for some hardware components, which
motivates the needs of non-preemptive or limited-preemptive scheduling.
We present a safe sufficient schedulability test
for non-preemptive (NP) fixed priority scheduling that can verify the
schedulability for Deadline Monotonic (DM-NP) and Rate Monotonic
(RM-NP) scheduling in linear time, if task orders according to priority and
period are given. This test leads to a better 
upper bound on the speedup factor for 
DM-NP and RM-NP in comparison to Earliest Deadline First (EDF-NP) than previously known, 
closing the gab between lower and upper bound.
We improve our test, resulting in interesting properties of the blocking time
that allow to determine schedulability by only considering the schedulability of
the preemptive case if some conditions are met. Furthermore, we present a
utilization bound for RM-NP, based on the ratio \gamma >0 of the
upper bound of the maximum blocking time to the execution time, significantly improving previous results.},
}