3 Search Results for "Mueller-Gritschneder, Daniel"


Document
Memory Latency Distribution-Driven Regulation for Temporal Isolation in MPSoCs

Authors: Ahsan Saeed, Denis Hoornaert, Dakshina Dasari, Dirk Ziegenbein, Daniel Mueller-Gritschneder, Ulf Schlichtmann, Andreas Gerstlauer, and Renato Mancuso

Published in: LIPIcs, Volume 262, 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)


Abstract
Temporal isolation is one of the most significant challenges that must be addressed before Multi-Processor Systems-on-Chip (MPSoCs) can be widely adopted in mixed-criticality systems with both time-sensitive real-time (RT) applications and performance-oriented non-real-time (NRT) applications. Specifically, the main memory subsystem is one of the most prevalent causes of interference, performance degradation and loss of isolation. Existing memory bandwidth regulation mechanisms use static, dynamic, or predictive DRAM bandwidth management techniques to restore the execution time of an application under contention as close as possible to the execution time in isolation. In this paper, we propose a novel distribution-driven regulation whose goal is to achieve a timeliness objective formulated as a constraint on the probability of meeting a certain target execution time for the RT applications. Using existing interconnect-level Performance Monitoring Units (PMU), we can observe the Cumulative Distribution Function (CDF) of the per-request memory latency. Regulation is then triggered to enforce first-order stochastical dominance with respect to a desired reference. Consequently, it is possible to enforce that the overall observed execution time random variable is dominated by the reference execution time. The mechanism requires no prior information of the contending application and treats the DRAM subsystem as a black box. We provide a full-stack implementation of our mechanism on a Commercial Off-The-Shelf (COTS) platform (Xilinx Ultrascale+ MPSoC), evaluate it using real and synthetic benchmarks, experimentally validate that the timeliness objectives are met for the RT applications, and demonstrate that it is able to provide 2.2x more overall throughput for NRT applications compared to DRAM bandwidth management-based regulation approaches.

Cite as

Ahsan Saeed, Denis Hoornaert, Dakshina Dasari, Dirk Ziegenbein, Daniel Mueller-Gritschneder, Ulf Schlichtmann, Andreas Gerstlauer, and Renato Mancuso. Memory Latency Distribution-Driven Regulation for Temporal Isolation in MPSoCs. In 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 262, pp. 4:1-4:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{saeed_et_al:LIPIcs.ECRTS.2023.4,
  author =	{Saeed, Ahsan and Hoornaert, Denis and Dasari, Dakshina and Ziegenbein, Dirk and Mueller-Gritschneder, Daniel and Schlichtmann, Ulf and Gerstlauer, Andreas and Mancuso, Renato},
  title =	{{Memory Latency Distribution-Driven Regulation for Temporal Isolation in MPSoCs}},
  booktitle =	{35th Euromicro Conference on Real-Time Systems (ECRTS 2023)},
  pages =	{4:1--4:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-280-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{262},
  editor =	{Papadopoulos, Alessandro V.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2023.4},
  URN =		{urn:nbn:de:0030-drops-180339},
  doi =		{10.4230/LIPIcs.ECRTS.2023.4},
  annote =	{Keywords: temporal isolation, memory latency, real-time system, multi-core}
}
Document
MonTM: Monitoring-Based Thermal Management for Mixed-Criticality Systems

Authors: Marcel Mettler, Martin Rapp, Heba Khdr, Daniel Mueller-Gritschneder, Jörg Henkel, and Ulf Schlichtmann

Published in: OASIcs, Volume 107, 14th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 12th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2023)


Abstract
With a rapidly growing functionality of embedded real-time applications, it becomes inevitable to integrate tasks of different safety integrity levels on one many-core processor leading to a large-scale mixed-criticality system. In this process, it is not sufficient to only isolate shared architectural resources, as different tasks executing on different cores also possibly interfere via the many-core processor’s thermal management. This can possibly lead to best-effort tasks causing deadline violations for safety-critical tasks. In order to prevent such a scenario, we propose a monitoring-based hardware extension that communicates imminent thermal violations between cores via a lightweight interconnect. Building on this infrastructure, we propose a thermal strategy such that best-effort tasks can be throttled in favor of safety-critical tasks. Furthermore, assigning static voltage/frequency (V/f) levels to each safety-critical task based on their worst-case execution time may result in unnecessary high V/f levels when the actual execution finishes faster. To free the otherwise wasted thermal resources, our solution monitors the progress of safety-critical tasks to detect slack and safely reduce their V/f levels. This increases the thermal headroom for best-effort tasks, boosting their performance. In our evaluation, we demonstrate our approach on an 80-core processor to show that it satisfies the thermal and deadline requirements, and simultaneously reduces the run-time of best-effort tasks by up to 45% compared to the state of the art.

Cite as

Marcel Mettler, Martin Rapp, Heba Khdr, Daniel Mueller-Gritschneder, Jörg Henkel, and Ulf Schlichtmann. MonTM: Monitoring-Based Thermal Management for Mixed-Criticality Systems. In 14th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 12th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2023). Open Access Series in Informatics (OASIcs), Volume 107, pp. 5:1-5:12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{mettler_et_al:OASIcs.PARMA-DITAM.2023.5,
  author =	{Mettler, Marcel and Rapp, Martin and Khdr, Heba and Mueller-Gritschneder, Daniel and Henkel, J\"{o}rg and Schlichtmann, Ulf},
  title =	{{MonTM: Monitoring-Based Thermal Management for Mixed-Criticality Systems}},
  booktitle =	{14th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 12th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2023)},
  pages =	{5:1--5:12},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-269-3},
  ISSN =	{2190-6807},
  year =	{2023},
  volume =	{107},
  editor =	{Bispo, Jo\~{a}o and Charles, Henri-Pierre and Cherubin, Stefano and Massari, Giuseppe},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.PARMA-DITAM.2023.5},
  URN =		{urn:nbn:de:0030-drops-177250},
  doi =		{10.4230/OASIcs.PARMA-DITAM.2023.5},
  annote =	{Keywords: Dynamic thermal management, mixed-criticality, monitoring}
}
Document
Keynote Talk
Going Beyond Fact-based Question Answering (Keynote Talk)

Authors: Erik T. Mueller

Published in: OASIcs, Volume 49, 2015 Imperial College Computing Student Workshop (ICCSW 2015)


Abstract
To solve the AI problem, we need to develop systems that go beyond answering fact-based questions. Watson has been hugely successful at answering fact-based questions, but to solve hard AI tasks like passing science tests and understanding narratives, we need to go beyond simple facts. In this talk, I discuss how the systems I have most recently worked on have approached this problem. Watson for Healthcare answers Doctor’s Dilemma medical competition questions, and WatsonPaths answers medical test preparation questions. These systems have achieved some success, but there is still a lot more to be done. Based on my experiences working on these systems, I discuss what I think the priorities should be going forward. First, to deal with the richness of human knowledge, we need to move beyond propositional logic to predicate logic. Second, to deal with the real world, we need to represent and reason about events and time. Third, to find multiple solutions and keep them distinct from one another, we need to use declarative problem solving methods like answer set programming. As one example of a formalism that embodies these three things, I review the event calculus described in my book Commonsense Reasoning. This formalism is especially useful for the narrative understanding task.

Cite as

Erik T. Mueller. Going Beyond Fact-based Question Answering (Keynote Talk). In 2015 Imperial College Computing Student Workshop (ICCSW 2015). Open Access Series in Informatics (OASIcs), Volume 49, p. 2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2015)


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@InProceedings{mueller:OASIcs.ICCSW.2015.2,
  author =	{Mueller, Erik T.},
  title =	{{Going Beyond Fact-based Question Answering}},
  booktitle =	{2015 Imperial College Computing Student Workshop (ICCSW 2015)},
  pages =	{2--2},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-000-2},
  ISSN =	{2190-6807},
  year =	{2015},
  volume =	{49},
  editor =	{Schulz, Claudia and Liew, Daniel},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/OASIcs.ICCSW.2015.2},
  URN =		{urn:nbn:de:0030-drops-54749},
  doi =		{10.4230/OASIcs.ICCSW.2015.2},
  annote =	{Keywords: Commonsense Reasoning}
}
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