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Documents authored by Pourmohseni, Behnaz


Document
Real-Time Task Migration for Dynamic Resource Management in Many-Core Systems

Authors: Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich

Published in: OASIcs, Volume 77, Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2020)


Abstract
Dynamic resource management strategies in embedded many-core systems rely on task migration to adapt the deployment (mapping) of applications dynamically, e.g., for thermal/power management or load balancing. In case of hard real-time applications, however, the current practice of on-line application adaptation is limited to reconfiguring the whole application between a set of statically computed mappings with statically verified timing guarantees. This heavily restricts the application’s adaptability. To enable hard real-time task migrations in many-core systems without relying on a static analysis, this paper presents (i) a predictable task migration mechanism supported with (ii) a lightweight migration timing analysis and (iii) a lightweight migration timing feasibility check which can be applied on-line to bound on the worst-case temporal overhead of a migration and examine the admissibility of this overhead w.r.t. the hard real-time requirements of the application. For a variety of applications and many-core platforms, we experimentally demonstrate the feasibility of hard real-time task migrations, the lightness of the proposed timing analysis and feasibility check for on-line use, and the advantage of the proposed task migration approach over mapping reconfiguration as the state-of-the-art real-time adaptation approach for many-core systems.

Cite as

Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich. Real-Time Task Migration for Dynamic Resource Management in Many-Core Systems. In Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2020). Open Access Series in Informatics (OASIcs), Volume 77, pp. 5:1-5:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{pourmohseni_et_al:OASIcs.NG-RES.2020.5,
  author =	{Pourmohseni, Behnaz and Smirnov, Fedor and Wildermann, Stefan and Teich, J\"{u}rgen},
  title =	{{Real-Time Task Migration for Dynamic Resource Management in Many-Core Systems}},
  booktitle =	{Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2020)},
  pages =	{5:1--5:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-136-8},
  ISSN =	{2190-6807},
  year =	{2020},
  volume =	{77},
  editor =	{Bertogna, Marko and Terraneo, Federico},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2020.5},
  URN =		{urn:nbn:de:0030-drops-117816},
  doi =		{10.4230/OASIcs.NG-RES.2020.5},
  annote =	{Keywords: Hard real-time, task migration, timing analysis, dynamic resource management, multi-core, many-core}
}
Document
Isolation-Aware Timing Analysis and Design Space Exploration for Predictable and Composable Many-Core Systems

Authors: Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich

Published in: LIPIcs, Volume 133, 31st Euromicro Conference on Real-Time Systems (ECRTS 2019)


Abstract
Composable many-core systems enable the independent development and analysis of applications which will be executed on a shared platform where the mix of concurrently executed applications may change dynamically at run time. For each individual application, an off-line DSE is performed to compute several mapping alternatives on the platform, offering Pareto-optimal trade-offs in terms of real-time guarantees, resource usage, etc. At run time, one mapping is then chosen to launch the application on demand. In this context, to enable an independent analysis of each individual application at design time, so-called inter-application isolation schemes are applied which specify temporal/spatial isolation policies between applications. State-of-the-art composable many-core systems are developed based on a fixed isolation scheme that is exclusively applied to every resource in every mapping of every application and use a timing analysis tailored to that isolation scheme to derive timing guarantees for each mapping. A fixed isolation scheme, however, heavily restricts the explored space of solutions and can, therefore, lead to suboptimality. Lifting this restriction necessitates a timing analysis that is applicable to mappings with an arbitrary mix of isolation schemes on different resources. To address this issue, in this paper, we (a) present an isolation-aware timing analysis that - unlike existing analyses - can handle multiple isolation schemes in combination within one mapping and delivers safe yet tight timing bounds by identifying and excluding interference scenarios that can never happen under the given combination of isolation schemes. Based on the timing analysis, we (b) present a DSE which explores the choices of isolation scheme per resource within each mapping and uses the proposed timing analysis for timing verification. Experimental results demonstrate that, for a variety of real-time applications and many-core platforms, the proposed approach achieves an improvement of up to 67% in the quality of delivered mappings compared to approaches based on a fixed isolation scheme.

Cite as

Behnaz Pourmohseni, Fedor Smirnov, Stefan Wildermann, and Jürgen Teich. Isolation-Aware Timing Analysis and Design Space Exploration for Predictable and Composable Many-Core Systems. In 31st Euromicro Conference on Real-Time Systems (ECRTS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 133, pp. 12:1-12:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2019)


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@InProceedings{pourmohseni_et_al:LIPIcs.ECRTS.2019.12,
  author =	{Pourmohseni, Behnaz and Smirnov, Fedor and Wildermann, Stefan and Teich, J\"{u}rgen},
  title =	{{Isolation-Aware Timing Analysis and Design Space Exploration for Predictable and Composable Many-Core Systems}},
  booktitle =	{31st Euromicro Conference on Real-Time Systems (ECRTS 2019)},
  pages =	{12:1--12:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-110-8},
  ISSN =	{1868-8969},
  year =	{2019},
  volume =	{133},
  editor =	{Quinton, Sophie},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2019.12},
  URN =		{urn:nbn:de:0030-drops-107491},
  doi =		{10.4230/LIPIcs.ECRTS.2019.12},
  annote =	{Keywords: Many-core systems, timing analysis, design space exploration (DSE), isolation scheme, predictability, composability}
}
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