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Guaranteed on-line weakly-hard real-time systems

G. Bernat, R. Cayssials
Proceedings 22nd IEEE Real-Time Systems Symposium (RTSS 2001) (Cat. No.01PR1420)  
A weakly hard real-time system is a system that can tolerate some degree of missed deadlines provided that this number is bounded and guaranteed off-line.  ...  In this paper we present an on-line scheduling framework called Bi-Modal Scheduler (BMS) for weakly-hard real-time systems. It is characterised by two modes of operation.  ...  To address the issues of real-time systems that can miss deadlines we introduce the concept of weakly-hard real-time system [3] : Definition 1 (Weakly-hard) A weakly-hard real-time system is a system  ... 
doi:10.1109/real.2001.990593 dblp:conf/rtss/BernatC01 fatcat:4tad2543ynb2thrftopumf256u

Energy-constrained scheduling for weakly-hard real-time systems

T.A. AlEnawy, H. Aydin
2005 26th IEEE International Real-Time Systems Symposium (RTSS'05)  
In this paper, we explore performance optimization problems for real-time systems that have to rely on a fixed energy budget during an operation/mission.  ...  We present on-line speed adjustment algorithms to exploit the slack time of skipped and completed jobs.  ...  Early work on the so-called 'RT-DVS' problem focuses on providing feasibility guarantees with the reduced CPU speed to maximize the energy savings, for various task/system models and on-line/off-line scheduling  ... 
doi:10.1109/rtss.2005.18 dblp:conf/rtss/AlEnawyA05 fatcat:hofu35gifree7naqep6agaxk6e

System Wide Dynamic Power Management for Weakly Hard Real-Time Systems

Linwei Niu, Gang Quan
2006 Journal of Low Power Electronics  
Kim and Ha [13] proposed a technique for hard real-time system, while scheduling decisions are made on a timeslot-by-timeslot basis.  ...  Jejurikar and Gupta [11] introduced a heuristic search In this section, we first introduce the system model and the related work on real-time scheduling with (m,k)-firm guarantee.  ...  These approaches cannot be applied for real-time system with weakly hard real-time constraints since the famous condition, i.e., U ≤ 1 is not necessary for a weakly hard real-time system to be feasible  ... 
doi:10.1166/jolpe.2006.101 fatcat:zmbls6ouyjfxpiwuswr35zk2xe

Weakly hard real-time systems

G. Bernat, A. Burns, A. Liamosi
2001 IEEE transactions on computers  
We introduce the concept of weakly hard real-time systems to model real-time systems that can tolerate a clearly specified degree of missed deadlines.  ...  Also, adding predictability on the pattern of missed deadlines for soft and firm real-time systems is desirable, for instance, to guarantee levels of quality of service.  ...  We call this type of system weakly hard real-time system. Formally: Definition 1 (weakly hard).  ... 
doi:10.1109/12.919277 fatcat:dmlbcrckgbccvm3afgy74jce5m

Peripheral-Conscious Scheduling on Energy Minimization for Weakly Hard Real-time Systems

Linwei Niu, Gang Quan
2007 2007 Design, Automation & Test in Europe Conference & Exhibition  
Extensive simulation studies demonstrate that our approach can effectively reduce the system-wide energy consumption while guaranteeing the weakly hard constraints at the same time.  ...  In this paper, we present a dynamic scheduling algorithm to minimize the energy consumption by both the DVS processor and peripheral devices in a weakly hard real-time system.  ...  The weakly hard real-time model is more accurate for practical applications.  ... 
doi:10.1109/date.2007.364387 dblp:conf/date/NiuQ07 fatcat:xxt62gjjyndvjf26nagsmi3f3m

Verifying Weakly-Hard Real-Time Properties of Traffic Streams in Switched Networks

Leonie Ahrendts, Sophie Quinton, Thomas Boroske, Rolf Ernst, Marc Herbstritt
2018 Euromicro Conference on Real-Time Systems  
A weakly-hard real-time guarantee specifies an upper bound on the maximum number m of deadline misses of a task in a sequence of k consecutive executions.  ...  performance analysis Keywords and phrases embedded and cyber-physical systems, weakly-hard real-time systems and networks, timing analysis  ...  The method builds on (1) CPA, a compositional performance verification framework for hard real-time guarantees, and (2) TWCA, an analysis method which derives weakly-hard real-time guarantees for systems  ... 
doi:10.4230/lipics.ecrts.2018.15 dblp:conf/ecrts/AhrendtsQBE18 fatcat:zwxbja44rjel7dfcopiksmbdri

Energy reduction in weakly hard real time systems

Yashwant Singh, Mayank Popli, Shiv Shankar Prasad Shukla
2012 2012 1st International Conference on Recent Advances in Information Technology (RAIT)  
Real Time Systems can be classified into Hard, Soft and Firm Real Time Systems depending on the consequences of a task missing its deadline.  ...  The Generalized case of Real Time Systems is Weakly Hard Real Time System which is motivation of the observation for real time applications when some deadline misses are acceptable as long as they are  ...  When a system is considered soft real time system, there is some room for lateness. The generalized case of real time systems is weakly hard real time systems.  ... 
doi:10.1109/rait.2012.6194555 dblp:conf/rait/SinghPS12 fatcat:7veb3xq5src3dg6oadtlvn34su

Convergence Rate Abstractions for Weakly-Hard Real-Time Control [article]

Maximilian Gaukler, Tim Rheinfels, Peter Ulbrich, Günter Roppenecker
2020 arXiv   pre-print
This approach simplifies the stability analysis of weakly-hard real-time control systems.  ...  Here, weakly-hard real-time control systems are a common approach which relaxes timing constraints and leverages the inherent robustness of controllers.  ...  Cas+06 ; Cer+02] to weakly-hard real-time systems that shift away from stringent deadlines.  ... 
arXiv:1912.09871v2 fatcat:nyedgcteivbo3e6csoifouqj5a

Weakly-hard Real-time Guarantees for Earliest Deadline First Scheduling of Independent Tasks

Zain A. H. Hammadeh, Sophie Quinton, Rolf Ernst
2019 ACM Transactions on Embedded Computing Systems  
Many practical real-time systems can de facto sustain a bounded number of deadline-misses, i.e., they have Weakly-Hard Real-Time (WHRT) constraints rather than hard real-time constraints.  ...  The current trend in modeling and analyzing real-time systems is toward tighter yet safe timing constraints.  ...  Safety-critical real-time systems require hard real-time guarantees.  ... 
doi:10.1145/3356865 fatcat:a2jd6hsfrvda5jtzfgiebjegye

A Design Methodology for Weakly-Hard Real-Time Control

Mongi Ben Gaid, Daniel Simon, Olivier Sename
2008 IFAC Proceedings Volumes  
The problem of the integrated control and weakly-hard real-time scheduling is addressed.  ...  A design method of optimal control laws for the weakly-hard execution model is then proposed.  ...  CONCLUSION A methodology for control and weakly-hard real-time scheduling co-design was proposed.  ... 
doi:10.3182/20080706-5-kr-1001.01736 fatcat:w6ygy4s73vfonofhaqsgq24ms4

Finite ready queues as a mean for overload reduction in weakly-hard real-time systems

Leonie Ahrendts, Sophie Quinton, Rolf Ernst
2017 Proceedings of the 25th International Conference on Real-Time Networks and Systems - RTNS '17  
We present an analysis method which is to the best of our knowledge the rst one able to give (a) worst-case response times guarantees as well as (b) weakly-hard guarantees for tasks which are executed  ...  Finite ready queues, implemented by bu ers, are a system reality in embedded real-time computing systems and networks.  ...  The modern concept of weakly-hard real-time (WHRT) computing systems [2] takes this reality into account.  ... 
doi:10.1145/3139258.3139259 dblp:conf/rtns/AhrendtsQE17 fatcat:5t4xbkgmm5gbpo2yxqwi527e4q

SAW: A Tool for Safety Analysis of Weakly-Hard Systems [chapter]

Chao Huang, Kai-Chieh Chang, Chung-Wei Lin, Qi Zhu
2020 Lecture Notes in Computer Science  
We introduce SAW, a tool for safety analysis of weakly-hard systems, in which traditional hard timing constraints are relaxed to allow bounded deadline misses for improving design flexibility and runtime  ...  Based on graph theory and dynamic programming, our approach can effectively find the safe initial set (consisting of a set of grids), from which the system can be proven safe under given weakly-hard constraints  ...  Introduction Hard timing constraints, where deadlines should always been met, have been widely used in real-time systems to ensure system safety.  ... 
doi:10.1007/978-3-030-53288-8_26 fatcat:ek2gppyd4jeinnzv6dzausy7iy

Beyond the Weakly Hard Model: Measuring the Performance Cost of Deadline Misses

Paolo Pazzaglia, Luigi Pannocchi, Alessandro Biondi, Marco Di Natale, Marc Herbstritt
2018 Euromicro Conference on Real-Time Systems  
hard deadlines) on a task model.  ...  Most works in schedulability analysis theory are based on the assumption that constraints on the performance of the application can be expressed by a very limited set of timing constraints (often simply  ...  We presented a new methodology to compute a state machine abstraction that allows to relate the performance of a control application to a sequence of deadline hits and misses, subject to weakly-hard constraints  ... 
doi:10.4230/lipics.ecrts.2018.10 dblp:conf/ecrts/PazzagliaPBN18 fatcat:3b44km4o2jbfvbntk2no3lhq6a

SAW: A Tool for Safety Analysis of Weakly-hard Systems [article]

Chao Huang, Kai-Chieh Chang, Chung-Wei Lin, Qi Zhu
2020 arXiv   pre-print
In this work, we propose a new technique for infinite-time safety verification of general nonlinear weakly-hard systems.  ...  We introduce SAW, a tool for safety analysis of weakly-hard systems, in which traditional hard timing constraints are relaxed to allow bounded deadline misses for improving design flexibility and runtime  ...  Introduction Hard timing constraints, where deadlines should always been met, have been widely used in real-time systems to ensure system safety.  ... 
arXiv:2005.07159v1 fatcat:dxnp5b3s6ffvjg2rg5chzclbrq

Dynamic Scheduling of Skippable Periodic Tasks With Energy Efficiency In Weakly Hard Real-Time System

Santhi Baskaran, P Thambidurai
2010 International Journal of Computer Science & Information Technology (IJCSIT)  
Three algorithms namely Red Tasks Only (RTO), Blue When Possible (BWP) and Red as Late as Possible (RLP) are proposed in the literature to schedule the real-time tasks in Weakly-hard real-time systems.  ...  This paper proposes optimal slack management algorithms to make the above existing weakly hard real-time scheduling algorithms energy efficient using DVS and DPD techniques.  ...  Existing scheduling algorithms (without energy efficiency) for weakly-hard real-time systems are explained in Section 3.  ... 
doi:10.5121/ijcsit.2010.2610 fatcat:bsmp4eqaajcxrkvfccqgrfdsh4
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