5 Search Results for "Kramer, Simon"


Document
Top- k Frequent Patterns in Streams and Parameterized-Space LZ Compression

Authors: Patrick Dinklage, Johnnes Fischer, and Nicola Prezza

Published in: LIPIcs, Volume 301, 22nd International Symposium on Experimental Algorithms (SEA 2024)


Abstract
We present novel online approximations of the Lempel-Ziv 77 (LZ77) and Lempel-Ziv 78 (LZ78) compression schemes [Lempel & Ziv, 1977/1978] with parameterizable space usage based on estimating which k patterns occur the most frequently in the streamed input for parameter k. This new approach overcomes the issue of finding only local repetitions, which is a natural limitation of algorithms that compress using a sliding window or by partitioning the input into blocks. For this, we introduce the top-k trie, a summary for maintaining online the top-k frequent consecutive patterns in a stream of characters based on a combination of the Lempel-Ziv 78 compression scheme and the Misra-Gries algorithm for frequent item estimation in streams. Using straightforward encoding, our implementations yield compression ratios (output over input size) competitive with established general-purpose LZ-based compression utilities such as gzip or xz.

Cite as

Patrick Dinklage, Johnnes Fischer, and Nicola Prezza. Top- k Frequent Patterns in Streams and Parameterized-Space LZ Compression. In 22nd International Symposium on Experimental Algorithms (SEA 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 301, pp. 9:1-9:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{dinklage_et_al:LIPIcs.SEA.2024.9,
  author =	{Dinklage, Patrick and Fischer, Johnnes and Prezza, Nicola},
  title =	{{Top- k Frequent Patterns in Streams and Parameterized-Space LZ Compression}},
  booktitle =	{22nd International Symposium on Experimental Algorithms (SEA 2024)},
  pages =	{9:1--9:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-325-6},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{301},
  editor =	{Liberti, Leo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SEA.2024.9},
  URN =		{urn:nbn:de:0030-drops-203748},
  doi =		{10.4230/LIPIcs.SEA.2024.9},
  annote =	{Keywords: compression, streaming, heavy hitters, algorithm engineering}
}
Document
Reachability-Based Response-Time Analysis of Preemptive Tasks Under Global Scheduling

Authors: Pourya Gohari, Jeroen Voeten, and Mitra Nasri

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)


Abstract
Global scheduling reduces the average response times as it can use the available computing cores more efficiently for scheduling ready tasks. However, this flexibility poses challenges in accurately quantifying interference scenarios, often resulting in either conservative response-time analyses or scalability issues. In this paper, we present a new response-time analysis for preemptive periodic tasks (or job sets) subject to release jitter under global job-level fixed-priority (JLFP) scheduling. Our analysis relies on the notion of schedule-abstraction graph (SAG), a reachability-based response-time analysis known for its potential accuracy and efficiency. Up to this point, SAG was limited to non-preemptive tasks due to the complexity of handling preemption when the number of preemptions and the moments they occur are not known beforehand. In this paper, we introduce the concept of time partitions and demonstrate how it facilitates the extension of SAG for preemptive tasks. Moreover, our paper provides the first response-time analysis for the global EDF(k) policy - a JLFP scheduling policy introduced in 2003 to address the Dhall’s effect. Our experiments show that our analysis is significantly more accurate compared to the state-of-the-art analyses. For example, we identify 12 times more schedulable task sets than existing tests for the global EDF policy (e.g., for systems with 6 to 16 tasks, 70% utilization, and 4 cores) with an average runtime of 30 minutes. We show that EDF(k) outperforms global RM and EDF by scheduling on average 24.9% more task sets (e.g., for systems with 2 to 10 cores and 70% utilization). Moreover, for the first time, we show that global JLFP scheduling policies (particularly, global EDF(k)) are able to schedule task sets that are not schedulable using well-known partitioning heuristics.

Cite as

Pourya Gohari, Jeroen Voeten, and Mitra Nasri. Reachability-Based Response-Time Analysis of Preemptive Tasks Under Global Scheduling. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 3:1-3:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{gohari_et_al:LIPIcs.ECRTS.2024.3,
  author =	{Gohari, Pourya and Voeten, Jeroen and Nasri, Mitra},
  title =	{{Reachability-Based Response-Time Analysis of Preemptive Tasks Under Global Scheduling}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{3:1--3:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.3},
  URN =		{urn:nbn:de:0030-drops-203064},
  doi =		{10.4230/LIPIcs.ECRTS.2024.3},
  annote =	{Keywords: Response-time analysis, global scheduling, preemptive, job-level fixed-priority scheduling policy, multicore, schedule-abstraction graph}
}
Document
Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis

Authors: Mario Günzel, Georg von der Brüggen, and Jian-Jia Chen

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)


Abstract
Tasks are called self-suspending if they can yield their ready state (specifically, releasing the processor while having highest priority) despite being incomplete, for instance, to offload computation to an external device or when waiting on access rights for shared resources or data. This self-suspending behavior requires special treatment when applying analytical results to compute worst-case response time bounds. One typical treatment is modeling self-suspension as release jitter in a so-called jitter-based analysis. The state of the art, when considering task-level fixed-priority scheduling, individually quantifies the jitter term of each higher-priority task by its worst-case response time minus its worst-case execution time. This work tightens the jitter term by taking the execution behavior of the other higher-priority tasks into account. Our improved jitter-based analysis analytically dominates the previous jitter-based analysis. Moreover, an evaluation for synthetically generated sporadic tasks demonstrates that this jitter term results in tighter worst-case response time bounds for self-suspending tasks. We observe an improvement for up to 55.89 % of the tasksets compared to the previous jitter-based analysis.

Cite as

Mario Günzel, Georg von der Brüggen, and Jian-Jia Chen. Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 4:1-4:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{gunzel_et_al:LIPIcs.ECRTS.2024.4,
  author =	{G\"{u}nzel, Mario and von der Br\"{u}ggen, Georg and Chen, Jian-Jia},
  title =	{{Tighter Worst-Case Response Time Bounds for Jitter-Based Self-Suspension Analysis}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{4:1--4:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.4},
  URN =		{urn:nbn:de:0030-drops-203074},
  doi =		{10.4230/LIPIcs.ECRTS.2024.4},
  annote =	{Keywords: Worst-Case Response Time, WCRT, Jitter, Self-Suspension, Analysis}
}
Document
Optimizing Per-Core Priorities to Minimize End-To-End Latencies

Authors: Francesco Paladino, Alessandro Biondi, Enrico Bini, and Paolo Pazzaglia

Published in: LIPIcs, Volume 298, 36th Euromicro Conference on Real-Time Systems (ECRTS 2024)


Abstract
Logical Execution Time (LET) allows decoupling the schedule of real-time periodic tasks from their communication, with the advantage of isolating the communication pattern from the variability of the schedule. However, when such tasks are organized in chains, the usage of LET at the task level does not necessarily transfer the same LET properties to the chain level. In this paper, we extend a LET-like model from tasks to chains spanning over multiple cores. We leverage the designed constant latency chains to optimize per-core priority assignment. Finally, we also provide a set of heuristic algorithms, that are compared in a large-scale experimental evaluation.

Cite as

Francesco Paladino, Alessandro Biondi, Enrico Bini, and Paolo Pazzaglia. Optimizing Per-Core Priorities to Minimize End-To-End Latencies. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 6:1-6:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{paladino_et_al:LIPIcs.ECRTS.2024.6,
  author =	{Paladino, Francesco and Biondi, Alessandro and Bini, Enrico and Pazzaglia, Paolo},
  title =	{{Optimizing Per-Core Priorities to Minimize End-To-End Latencies}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{6:1--6:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-324-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{298},
  editor =	{Pellizzoni, Rodolfo},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2024.6},
  URN =		{urn:nbn:de:0030-drops-203094},
  doi =		{10.4230/LIPIcs.ECRTS.2024.6},
  annote =	{Keywords: Cause-Effect Chains, Logical Execution Time, End-to-End Latency, Design Optimization, Task Priorities, Data Age, Reaction Time}
}
Document
Communication Centric Design in Complex Automotive Embedded Systems

Authors: Arne Hamann, Dakshina Dasari, Simon Kramer, Michael Pressler, and Falk Wurst

Published in: LIPIcs, Volume 76, 29th Euromicro Conference on Real-Time Systems (ECRTS 2017)


Abstract
Automotive embedded applications like the engine management system are composed of multiple functional components that are tightly coupled via numerous communication dependencies and intensive data sharing, while also having real-time requirements. In order to cope with complexity, especially in multi-core settings, various communication mechanisms are used to ensure data consistency and temporal determinism along functional cause-effect chains. However, existing timing analysis methods generally only support very basic communication models that need to be extended to handle the analysis of industry grade problems which involve more complex communication semantics. In this work, we give an overview of communication semantics used in the automotive industry and the different constraints to be considered in the design process. We also propose a method for model transformation to increase the expressiveness of current timing analysis methods enabling them to work with more complex communication semantics. We demonstrate this transformation approach for concrete implementations of two communication semantics, namely, implicit and LET communication. We discuss the impact on end-to-end latencies and communication overheads based on a full blown engine management system.

Cite as

Arne Hamann, Dakshina Dasari, Simon Kramer, Michael Pressler, and Falk Wurst. Communication Centric Design in Complex Automotive Embedded Systems. In 29th Euromicro Conference on Real-Time Systems (ECRTS 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 76, pp. 10:1-10:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@InProceedings{hamann_et_al:LIPIcs.ECRTS.2017.10,
  author =	{Hamann, Arne and Dasari, Dakshina and Kramer, Simon and Pressler, Michael and Wurst, Falk},
  title =	{{Communication Centric Design in Complex Automotive Embedded Systems}},
  booktitle =	{29th Euromicro Conference on Real-Time Systems (ECRTS 2017)},
  pages =	{10:1--10:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-037-8},
  ISSN =	{1868-8969},
  year =	{2017},
  volume =	{76},
  editor =	{Bertogna, Marko},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2017.10},
  URN =		{urn:nbn:de:0030-drops-71624},
  doi =		{10.4230/LIPIcs.ECRTS.2017.10},
  annote =	{Keywords: Communication semantics, logical execution time, implicit communication, automotive, embedded systems, scheduling simulation, Amalthea}
}
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