3 Search Results for "Samii, Soheil"


Document
Analysis of TSN Time-Aware Shapers Using Schedule Abstraction Graphs

Authors: Srinidhi Srinivasan, Geoffrey Nelissen, Reinder J. Bril, and Nirvana Meratnia

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


Abstract
IEEE Time-Sensitive Networking (TSN) is one of the main solutions considered by the industry to support time-sensitive communication in data-intensive safety-critical and mission-critical applications such as autonomous driving and smart manufacturing. IEEE TSN standardizes several mechanisms to support real-time traffic on Ethernet networks. Time-Aware Shapers (TAS) (IEEE 802.1Qbv) is the standardized mechanisms of TSN that is usually considered to provide the most deterministic behavior for packet forwarding. TAS regulates when traffic classes may forward incoming packets to the egress of a TSN switch using gates that are opened and closed according to a time-triggered schedule. State-of-the-art solutions to configure or analyze TAS do not allow for multiple traffic classes to have their TAS gates opened at the same time according to any arbitrary schedule. In this paper, we present the first response-time analysis for traffic shaped with TAS where no restriction is enforced on the gate schedule. The proposed analysis is exact. It is a non-trivial variant of the schedule abstraction graph analysis framework [Nasri and Brandenburg, 2017]. Experiments confirm the usefulness of the proposed analysis and show that it is promising for doing design-space exploration where non-conventional TAS gates configurations are investigated to, for instance, improve average-case performance without degrading the worst-case.

Cite as

Srinidhi Srinivasan, Geoffrey Nelissen, Reinder J. Bril, and Nirvana Meratnia. Analysis of TSN Time-Aware Shapers Using Schedule Abstraction Graphs. In 36th Euromicro Conference on Real-Time Systems (ECRTS 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 298, pp. 16:1-16:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{srinivasan_et_al:LIPIcs.ECRTS.2024.16,
  author =	{Srinivasan, Srinidhi and Nelissen, Geoffrey and Bril, Reinder J. and Meratnia, Nirvana},
  title =	{{Analysis of TSN Time-Aware Shapers Using Schedule Abstraction Graphs}},
  booktitle =	{36th Euromicro Conference on Real-Time Systems (ECRTS 2024)},
  pages =	{16:1--16:24},
  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.2024.16},
  URN =		{urn:nbn:de:0030-drops-203198},
  doi =		{10.4230/LIPIcs.ECRTS.2024.16},
  annote =	{Keywords: TSN, Time-Aware Shapers, TAS, SAG, Schedule Abstraction, latency}
}
Document
Recovery Time Considerations in Real-Time Systems Employing Software Fault Tolerance

Authors: Anand Bhat, Soheil Samii, and Ragunathan (Raj) Rajkumar

Published in: LIPIcs, Volume 106, 30th Euromicro Conference on Real-Time Systems (ECRTS 2018)


Abstract
Safety-critical real-time systems like modern automobiles with advanced driving-assist features must employ redundancy for crucial software tasks to tolerate permanent crash faults. This redundancy can be achieved by using techniques like active replication or the primary-backup approach. In such systems, the recovery time which is the amount of time it takes for a redundant task to take over execution on the failure of a primary task becomes a very important design parameter. The recovery time for a given task depends on various factors like task allocation, primary and redundant task priorities, system load and the scheduling policy. Each task can also have a different recovery time requirement (RTR). For example, in automobiles with automated driving features, safety-critical tasks like perception and steering control have strict RTRs, whereas such requirements are more relaxed in the case of tasks like heating control and mission planning. In this paper, we analyze the recovery time for software tasks in a real-time system employing Rate-Monotonic Scheduling (RMS). We derive bounds on the recovery times for different redundant task options and propose techniques to determine the redundant-task type for a task to satisfy its RTR. We also address the fault-tolerant task allocation problem, with the additional constraint of satisfying the RTR of each task in the system. Given that the problem of assigning tasks to processors is a well-known NP-hard bin-packing problem we propose computationally-efficient heuristics to find a feasible allocation of tasks and their redundant copies. We also apply the simulated annealing method to the fault-tolerant task allocation problem with RTR constraints and compare against our heuristics.

Cite as

Anand Bhat, Soheil Samii, and Ragunathan (Raj) Rajkumar. Recovery Time Considerations in Real-Time Systems Employing Software Fault Tolerance. In 30th Euromicro Conference on Real-Time Systems (ECRTS 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 106, pp. 23:1-23:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{bhat_et_al:LIPIcs.ECRTS.2018.23,
  author =	{Bhat, Anand and Samii, Soheil and Rajkumar, Ragunathan (Raj)},
  title =	{{Recovery Time Considerations in Real-Time Systems Employing Software Fault Tolerance}},
  booktitle =	{30th Euromicro Conference on Real-Time Systems (ECRTS 2018)},
  pages =	{23:1--23:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-075-0},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{106},
  editor =	{Altmeyer, Sebastian},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2018.23},
  URN =		{urn:nbn:de:0030-drops-89808},
  doi =		{10.4230/LIPIcs.ECRTS.2018.23},
  annote =	{Keywords: fault tolerance, real-time embedded systems, recovery time, real-time schedulability}
}
Document
The Multi-Domain Frame Packing Problem for CAN-FD

Authors: Prachi Joshi, Haibo Zeng, Unmesh D. Bordoloi, Soheil Samii, S. S. Ravi, and Sandeep K. Shukla

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


Abstract
The Controller Area Network with Flexible Data-Rate (CAN-FD) is a new communication protocol to meet the bandwidth requirements for the constantly growing volume of data exchanged in modern vehicles. The problem of frame packing for CAN-FD, as studied in the literature, assumes a single sub-system where one CAN-FD bus serves as the communication medium among several Electronic Control Units (ECUs). Modern automotive electronic systems, on the other hand, consist of several sub-systems, each facilitating a certain functional domain such as powertrain, chassis and suspension. A substantial fraction of all signals is exchanged across sub-systems. In this work, we study the frame packing problem for CAN-FD with multiple sub-systems, and propose a two-stage optimization framework. In the first stage, we pack the signals into frames with the objective of minimizing the bandwidth utilization. In the second stage, we extend Audsley's algorithm to assign priorities/identifiers to the frames. In case the resulting solution is not schedulable, our framework provides a potential repacking method. We propose two solution approaches: (a) an Integer Linear Programming (ILP) formulation that provides an optimal solution but is computationally expensive for industrial-size problems; and (b) a greedy heuristic that scales well and provides solutions that are comparable to optimal solutions. Experimental results show the efficiency of our optimization framework in achieving feasible solutions with low bandwidth utilization. The results also show a significant improvement over the case when there is no cross-domain consideration (as in prior work).

Cite as

Prachi Joshi, Haibo Zeng, Unmesh D. Bordoloi, Soheil Samii, S. S. Ravi, and Sandeep K. Shukla. The Multi-Domain Frame Packing Problem for CAN-FD. In 29th Euromicro Conference on Real-Time Systems (ECRTS 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 76, pp. 12:1-12:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


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@InProceedings{joshi_et_al:LIPIcs.ECRTS.2017.12,
  author =	{Joshi, Prachi and Zeng, Haibo and Bordoloi, Unmesh D. and Samii, Soheil and Ravi, S. S. and Shukla, Sandeep K.},
  title =	{{The Multi-Domain Frame Packing Problem for CAN-FD}},
  booktitle =	{29th Euromicro Conference on Real-Time Systems (ECRTS 2017)},
  pages =	{12:1--12:22},
  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.2017.12},
  URN =		{urn:nbn:de:0030-drops-71551},
  doi =		{10.4230/LIPIcs.ECRTS.2017.12},
  annote =	{Keywords: Frame Packing, CAN-FD, Integer Linear Programming, Audsley's Algorithm}
}
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