| 1. |
- Becker, Matthias, 1986-, et al.
(författare)
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A Generic Framework Facilitating Early Analysis of Data Propagation Delays in Multi-Rate Systems
- 2017
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Ingår i: The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17.
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Konferensbidrag (refereegranskat)abstract
- A majority of multi-rate real-time systems are constrained by a multitude of timing requirements, in addition to the traditional deadlines on well-studied response times. This means, the timing predictability of these systems not only depends on the schedulability of certain task sets but also on the timely propagation of data through the chains of tasks from sensors to actuators. In the automotive industry, four different timing constraints corresponding to various data propagation delays are commonly specified on the systems. This paper identifies and addresses the source of pessimism as well as optimism in the calculations for one such delay, namely the reaction delay, in the state-of-the-art analysis that is already implemented in several industrial tools. Furthermore, a generic framework is proposed to compute all the four end-to-end data propagation delays, complying with the established delay semantics, in a scheduler and hardware-agnostic manner. This allows analysis of the system models already at early development phases, where limited system information is present. The paper further introduces mechanisms to generate job-level dependencies, a partial ordering of jobs, which need to be satisfied by any execution platform in order to meet the data propagation timing requirements. The job-level dependencies are first added to all task chains of the system and then reduced to its minimum required set such that the job order is not affected. Moreover, a necessary schedulability test is provided, allowing for varying the number of CPUs. The experimental evaluations demonstrate the tightness in the reaction delay with the proposed framework as compared to the existing state-of-the-art and practice solutions.
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| 2. |
- Becker, Matthias, 1986-, et al.
(författare)
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A Many-Core based Execution Framework for IEC 61131-3
- 2015
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Ingår i: IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society. ; , s. 4525-4530
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Konferensbidrag (refereegranskat)abstract
- Programmable logic controllers are widely used for the control of automationsystems. The standard IEC 61131-3 defines the execution model as well as theprogramming languages for such systems. Nowadays, actuators and sensorsconnect to the programmable logic controller via automation buses. While suchbuses, as well as the sensors and actuators, become more and more powerful, ashift away from the current distributed operation of automation systems, closeto the field level, becomes possible. Instead, execution of complex controlfunctions can be relocated to more powerful hardware, and technologies. Thispaper presents an execution framework for IEC 61131-3, based on a many-coreprocessors. The presented execution model exploits the characteristics of theIEC 61131-3 applications as well as the characteristics of the many-core processor,yielding a predictable execution. We present the platform architectureand an algorithm to allocate a number of IEC 61131-3 conform applications.Experimental as well as simulation based evaluation is provided.
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| 3. |
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| 4. |
- Becker, Matthias, et al.
(författare)
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Analyzing End-to-End Delays in Automotive Systems at Various Levels of Timing Information
- 2016
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Ingår i: IEEE 4th International Workshop on Real-Time Computing and Distributed systems in Emerging Applications REACTION'16. - Porto, Portugal.
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Konferensbidrag (refereegranskat)abstract
- Software design for automotive systems is highly complex due to the presence of strict data age constraints for event chains in addition to task specific requirements. These age constraints define the maximum time for the propagation of data through an event chain consisting of independently triggered tasks. Tasks in event chains can have different periods, introducing over- and under-sampling effects, which additionally aggravates their timing analysis. Furthermore, different functionality in these systems, is developed by different suppliers before the final system integration on the ECU. The software itself is developed in a hardware agnostic manner and this uncertainty and limited information at the early design phases may not allow effective analysis of end-to-end delays during that phase. In this paper, we present a method to compute end-to-end delays given the information available in the design phases, thereby enabling timing analysis throughout the development process. The presented methods are evaluated with extensive experiments where the decreasing pessimism with increasing system information is shown.
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| 5. |
- Becker, Matthias, 1986-, et al.
(författare)
-
Analyzing end-to-end delays in automotive systems at various levels of timing information
- 2017
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Ingår i: ACM SIGBED Review. - : Association for Computing Machinery (ACM). - 1551-3688. ; 14:4, s. 8-13
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Tidskriftsartikel (refereegranskat)abstract
- Software design for automotive systems is highly complex due to the presence of strict data age constraints for event chains in addition to task specific requirements. These age constraints define the maximum time for the propagation of data through an event chain consisting of independently triggered tasks. Tasks in event chains can have different periods, introducing over- and under-sampling effects, which additionally aggravates their timing analysis. Furthermore, different functionality in these systems, is developed by different suppliers before the final system integration on the ECU. The software itself is developed in a hardware agnostic manner and this uncertainty and limited information at the early design phases may not allow effective analysis of end-to-end delays during that phase. In this paper, we present a method to compute end-to-end delays given the information available in the design phases, thereby enabling timing analysis throughout the development process. The presented methods are evaluated with extensive experiments where the decreasing pessimism with increasing system information is shown.
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| 6. |
- Becker, Matthias, 1986-
(författare)
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Consolidating Automotive Real-Time Applications on Many-Core Platforms
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Automotive systems have transitioned from basic transportation utilities to sophisticated systems. The rapid increase in functionality comes along with a steep increase in software complexity. This manifests itself in a surge of the number of functionalities as well as the complexity of existing functions. To cope with this transition, current trends shift away from today’s distributed architectures towards integrated architectures, where previously distributed functionality is consolidated on fewer, more powerful, computers. This can ease the integration process, reduce the hardware complexity, and ultimately save costs.One promising hardware platform for these powerful embedded computers is the many-core processor. A many-core processor hosts a vast number of compute cores, that are partitioned on tiles which are connected by a Network-on-Chip. These natural partitions can provide exclusive execution spaces for different applications, since most resources are not shared among them. Hence, natural building blocks towards temporally and spatially separated execution spaces exist as a result of the hardware architecture.Additionally to the traditional task local deadlines, automotive applications are often subject to timing constraints on the data propagation through a chain of semantically related tasks. Such requirements pose challenges to the system designer as they are only able to verify them after the system synthesis (i.e. very late in the design process).In this thesis, we present methods that transform complex timing constraints on the data propagation delay to precedence constraints between individual jobs. An execution framework for the cluster of the many-core is proposed that allows access to cluster external memory while it avoids contention on shared resources by design. A partitioning and configuration of the Network-on-Chip provides isolation between the different applications and reduces the access time from the clusters to external memory. Moreover, methods that facilitate the verification of data propagation delays in each development step are provided.
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| 7. |
- Becker, Matthias, et al.
(författare)
-
Contention-Free Execution of Automotive Applications on a Clustered Many-Core Platform
- 2016
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Ingår i: 28th Euromicro Conference on Real-Time Systems ECRTS'16. - Toulouse, France. - 9781509028115 ; , s. 14-24
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Konferensbidrag (refereegranskat)abstract
- Next generations of compute-intensive real-time applications in automotive systems will require more powerful computing platforms. One promising power-efficient solution for such applications is to use clustered many-core architectures. However, ensuring that real-time requirements are satisfied in the presence of contention in shared resources, such as memories, remains an open issue. This work presents a novel contention-free execution framework to execute automotive applications on such platforms. Privatization of memory banks together with defined access phases to shared memory resources is the backbone of the framework. An Integer Linear Programming (ILP) formulation is presented to find the optimal time-triggered schedule for the on-core execution as well as for the access to shared memory. Additionally a heuristic solution is presented that generates the schedule in a fraction of the time required by the ILP. Extensive evaluations show that the proposed heuristic performs only 0.5% away from the optimal solution while it outperforms a baseline heuristic by 67%. The applicability of the approach to industrially sized problems is demonstrated in a case study of a software for Engine Management Systems.
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| 8. |
- Becker, Matthias, et al.
(författare)
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Dynamic Power Management for Thermal Control of Many-Core Real-Time Systems
- 2014
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Ingår i: Sigbed Review. - : Association for Computing Machinery (ACM). - 1551-3688. ; 11:3, s. 26-29
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Tidskriftsartikel (refereegranskat)abstract
- Many-Core systems, processors incorporating numerous cores interconnected by a Network on Chip (NoC), provide the computing power needed by future applications. High power density caused by the steadily shrinking transistor size, which is still following Moore's law, leads to a number of problems such as overheating cores, affecting processor reliability and lifetime. Embedded real-time systems are exposed to a changing ambient temperature and thus need to adapt their configuration in order to keep the individual core temperature below critical values. %Targeting embedded real-time systems, systems need to adapt to changing environments. In our approach a hysteresis controller is implemented on each core, triggering a redistribution of the cores and the transition into idle state allowing the core to cool down. We propose two approaches, one global and one local approach, to redistribute the tasks and relive overheating cores during runtime. We evaluate the two proposed approaches by comparing them against each other based on simulations.
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| 9. |
- Becker, Matthias, 1986-
(författare)
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Efficient Resource Management for Many-Core based Industrial Real-Time Systems
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increased complexity of today’s industrial embedded systems stands inneed for more computational power while most systems must adhere to a restrictedenergy consumption, either to prolong the battery lifetime or to reduceoperational costs. The many-core processor is therefore a natural fit. Due tothe simple architecture of the compute cores, and therefore their good analyzability,such processors are additionally well suited for real-time applications.In our research, we focus on two particular problems which need to be addressedin order to pave the way into the many-core era. The first area is powerand thermal aware execution frameworks, where we present different energyaware extensions to well known load balancing algorithms, allowing them todynamically scale the number of active cores depending on their workload.In contrast, an additional framework is presented which balances workloadsto minimize temperature gradients on the die. The second line of works focuseson industrial standards in the face of massively parallel platforms, wherewe address the automotive and automation domain. We present an executionframework for IEC 61131-3 applications, allowing the consolidation of severalIEC 61131-3 applications on the same platform. Additionally, we discussseveral architectural options for the AUTOSAR software architecture on suchmassively parallel platforms.
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| 10. |
- Becker, Matthias, 1986-, et al.
(författare)
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End-to-End Timing Analysis of Cause-Effect Chains in Automotive Embedded Systems
- 2017
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Ingår i: Journal of systems architecture. - : Elsevier BV. - 1383-7621 .- 1873-6165. ; 80:Supplement C, s. 104-113
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Tidskriftsartikel (refereegranskat)abstract
- Automotive embedded systems are subjected to stringent timing requirements that need to be verified. One of the most complex timing requirement in these systems is the data age constraint. This constraint is specified on cause- effect chains and restricts the maximum time for the propagation of data through the chain. Tasks in a cause-effect chain can have different activation patterns and different periods, that introduce over- and under-sampling effects, which additionally aggravate the end-to-end timing analysis of the chain. Furthermore, the level of timing information available at various development stages (from modeling of the software architecture to the software implementation) varies a lot, the complete timing information is available only at the implementation stage. This uncertainty and limited timing information can restrict the end-to-end timing analysis of these chains. In this paper, we present methods to compute end-to-end delays based on different levels of system information. The characteristics of different communication semantics are further taken into account, thereby enabling timing analysis throughout the development process of such heterogeneous software systems. The presented methods are evaluated with extensive experiments. As a proof of concept, an industrial case study demonstrates the applicability of the proposed methods following a state-of-the-practice development process.
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