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Documents authored by West, Richard


Document
PAStime: Progress-Aware Scheduling for Time-Critical Computing

Authors: Soham Sinha, Richard West, and Ahmad Golchin

Published in: LIPIcs, Volume 165, 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)


Abstract
Over-estimation of worst-case execution times (WCETs) of real-time tasks leads to poor resource utilization. In a mixed-criticality system (MCS), the over-provisioning of CPU time to accommodate the WCETs of highly critical tasks may lead to degraded service for less critical tasks. In this paper we present PAStime, a novel approach to monitor and adapt the runtime progress of highly time-critical applications, to allow for improved service to lower criticality tasks. In PAStime, CPU time is allocated to time-critical tasks according to the delays they experience as they progress through their control flow graphs. This ensures that as much time as possible is made available to improve the Quality-of-Service of less critical tasks, while high-criticality tasks are compensated after their delays. This paper describes the integration of PAStime with Adaptive Mixed-criticality (AMC) scheduling. The LO-mode budget of a high-criticality task is adjusted according to the delay observed at execution checkpoints. This is the first implementation of AMC in the scheduling framework of LITMUS^RT, which is extended with our PAStime runtime policy and tested with real-time Linux applications such as object classification and detection. We observe in our experimental evaluation that AMC-PAStime significantly improves the utilization of the low-criticality tasks while guaranteeing service to high-criticality tasks.

Cite as

Soham Sinha, Richard West, and Ahmad Golchin. PAStime: Progress-Aware Scheduling for Time-Critical Computing. In 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 165, pp. 3:1-3:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{sinha_et_al:LIPIcs.ECRTS.2020.3,
  author =	{Sinha, Soham and West, Richard and Golchin, Ahmad},
  title =	{{PAStime: Progress-Aware Scheduling for Time-Critical Computing}},
  booktitle =	{32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)},
  pages =	{3:1--3:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-152-8},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{165},
  editor =	{V\"{o}lp, Marcus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2020.3},
  URN =		{urn:nbn:de:0030-drops-123668},
  doi =		{10.4230/LIPIcs.ECRTS.2020.3},
  annote =	{Keywords: progress-aware scheduling, code instrumentation, timing annotation}
}
Document
smARTflight: An Environmentally-Aware Adaptive Real-Time Flight Management System

Authors: Anam Farrukh and Richard West

Published in: LIPIcs, Volume 165, 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)


Abstract
Multi-rotor drones require real-time sensor data processing and control to maintain flight stability, which is made more challenging by external disturbances such as wind. In this paper we introduce smARTflight: an environmentally-aware adaptive real-time flight management system. smARTflight adapts the execution frequencies of flight control tasks according to timing and safety-critical constraints, in response to transient fluctuations of a drone’s attitude. In contrast to current state-of-the-art methods, smARTflight’s criticality-aware scheduler reduces the latency to return to a steady-state target attitude. The system also improves the overall control accuracy and lowers the frequency of adjustments to motor speeds to conserve power. A comparative case-study with a well-known autopilot shows that smARTflight reduces unnecessary control loop executions under stable conditions, while reducing response time latency by as much as 60% in a given axis of rotation when subjected to a 15° step attitude disturbance.

Cite as

Anam Farrukh and Richard West. smARTflight: An Environmentally-Aware Adaptive Real-Time Flight Management System. In 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 165, pp. 24:1-24:22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


Copy BibTex To Clipboard

@InProceedings{farrukh_et_al:LIPIcs.ECRTS.2020.24,
  author =	{Farrukh, Anam and West, Richard},
  title =	{{smARTflight: An Environmentally-Aware Adaptive Real-Time Flight Management System}},
  booktitle =	{32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)},
  pages =	{24:1--24:22},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-152-8},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{165},
  editor =	{V\"{o}lp, Marcus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2020.24},
  URN =		{urn:nbn:de:0030-drops-123874},
  doi =		{10.4230/LIPIcs.ECRTS.2020.24},
  annote =	{Keywords: adaptive real-time systems, safety criticality, flight controller, multi-rotor drones, environmental awareness}
}
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