| 1. |
- Inam, Rafia, 1974-, et al.
(författare)
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Compositional analysis for the multi-resource server - a technical report.
- 2014
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Rapport (refereegranskat)abstract
- The Multi-Resource Server (MRS) technique has been proposed toenable predictable execution of memory intensive real-time applicationson COTS multi-core platforms. It uses resource reservationapproaches in the context of CPU-bandwidth and memory-busbandwidth reservations to bound the interferences between the applicationsrunning on the same core as well as between the applicationsrunning on different cores. In this paper we present a completecompositional schedulability analysis for the Multi-ResourceServer technique. Based on the proposed analysis, we further providean experimental study that investigates the behaviour of theMRS and identify the factors that contribute mostly on the overallsystem performance.
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| 2. |
- Inam, Rafia, 1974-, et al.
(författare)
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Hard Real-time Support for Hierarchical Scheduling in FreeRTOS
- 2011
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Ingår i: Proceedings of 7th annual workshop on Operating Systems Platforms for Embedded Real-Time Applications July 5th, 2011 in Porto, Portugal. ; , s. 51-60
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Konferensbidrag (refereegranskat)abstract
- This paper presents extensions to the previous implementationof two-level Hierarchical Scheduling Framework(HSF) for FreeRTOS. The results presented here allow the useof HSF for FreeRTOS in hard-real time applications, with thepossibility to include legacy applications and components notexplicitly developed for hard real-time or the HSF.Specifically, we present the implementations of (i) global andlocal resource sharing using the Hierarchical Stack ResourcePolicy and Stack Resource Policy respectively, (ii) kernel supportfor the periodic task model, and (iii) mapping of original FreeRTOSAPI to the extended FreeRTOS HSF API. We also presentevaluations of overheads and behavior for different alternativeimplementations of HSRP with overrun from experiments on theAVR 32-bit board EVK1100. In addition, real-time schedulinganalysis with models of the overheads of our implementation ispresented.
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| 3. |
- Inam, Rafia, 1974-
(författare)
-
Hierarchical scheduling for predictable execution of real-time software components and legacy systems
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation presents techniques to achieve predictable execution of coarse-grained software components and for preservation of temporal properties of components during their integration and reuse.The dissertation presents a novel concept runnable virtual node (RVN) which interaction with the environment is bounded both by a functional and a temporal interface, and the validity of its internal temporal behaviour is preserved when integrated with other components or when reused in a new environment. The realization of RVN exploits techniques for hierarchical scheduling to achieve temporal isolation, and the principles from component-based software-engineering to achieve functional isolation. The proof-of-concept case studies executed on a micro-controller demonstrate the preserving of real-time properties within software components for predictable integration and reusability in a new environment, in both hierarchical scheduling and RVN contexts.Further, a multi-resource server (MRS) is proposed and implemented to enable predictable execution when composing multiple real-time components on a COTS multicore platform. MRS uses resource reservation for both CPU-bandwidth and memory-bus bandwidth to bound the interferences between tasks running on the same core, as well as, between tasks running on different cores. The later could, without MRS, interfere with each other due to contention on a shared memory-bus and memory. The results indicated that MRS can be used to "encapsulate" legacy systems and to give them enough resources to fulfill their purpose. In the dissertation, the compositional schedulability analysis for MRS is also provided and an experimental study is performed to bring insight on the correlation between the server budgets.We believe that the proposed approaches enable a faster software integration and support legacy reuse and that this work transcend the boundaries of software engineering and real-time systems.
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| 4. |
- Inam, Rafia, 1974-, et al.
(författare)
-
Support for Legacy Real-Time Applications in an HSF-Enabled FreeRTOS - a technical report
- 2014
-
Rapport (refereegranskat)abstract
- This paper presents a runtime support to consolidate legacy together with other real-time applications, running a single instance of a real-time operating system (RTOS), and sharing system resources. In this context, we resort to the hierarchical scheduling framework (HSF) to provide tem- poral partitions for dierent applications, supporting their independent development and real-time analysis, thus resulting on a predictable inte- gration. In particular, the paper focuses on a constructive element, the legacy server that allows executing code that is unaware of the temporal partition within which it is deployed. Furthermore, we discuss the chal- lenges that need to be addressed to execute a legacy application in an HSF without modications to the original code. We focus on the chal- lenge of enabling sharing system resources, both hardware and software, as typically found in most industrial software systems. We propose a novel solution based on wrappers for the required RTOS system calls. We implement our ideas in a concrete implementation on FreeRTOS OS, taking advantage of a prior HSF implementation. The validation is performed by a proof-of-concept case study that shows a successful integration of a legacy application that uses shared resources in a system that executes other applications.
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| 5. |
- Inam, Rafia, 1974-, et al.
(författare)
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Worst Case Delay Analysis of a DRAM Memory Request for COTS Multicore Architectures
- 2014
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Konferensbidrag (refereegranskat)abstract
- Dynamic RAM (DRAM) is a source of memory contention and interference problems on commercial of the shelf (COTS) multicore architectures. Due to its variable access time, it can greatly influence the task's WCET and can lead to unpredictability. In this paper, we provide a worst case delay analysis for a DRAM memory request to safely bound memory contention on multicore architectures. We derive a worst-case service time for a single memory request and then combine it with the per-request memory interference that can be generated by the tasks executing on same or different cores in order to generate the delay bound.
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| 6. |
- Afshar, Sara, et al.
(författare)
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Intra-component Resource Sharing on a Virtual Multiprocessor Platform
- 2016
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Ingår i: ACM SIGBED Review. - : Association for Computing Machinery (ACM). - 1551-3688. ; , s. 31-32
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Konferensbidrag (refereegranskat)abstract
- Component-based software development facilitates the development process of large and complex software systems. By the advent of multiprocessors, the independently developed components can be integrated on a multi-core platform to achieve an efficient use of system hardware and a decrease in system power consumption and costs. In this paper, we consider a virtual multiprocessor platform where each component can be dynamically allocated to any set of processors of the platform with a maximum concurrency level. Global-EDF is used for intra-component scheduling. The existing analysis for such systems have assumed that tasks are independent. In this paper, we enable intra-component resource sharing for this platform. We investigate using a spin-based resource sharing protocol with the accompanying analysis that extends the existing analysis for independent tasks. We briefly illustrate and evaluate our initial results with an example.
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| 7. |
- Afshar, Sara Zargari, et al.
(författare)
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An optimal spin-lock priority assignment algorithm for real-time multi-core 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
- Support for exclusive access to shared (global) resources is instrumental in the context of embedded real-time multi-core systems, and mechanisms for achieving such access must be deterministic and efficient. There exist two traditional approaches for multiprocessors when a task requests a global resource that is locked by a task on a remote core: a spin-based approach, i.e. non-preemptive busy waiting for the resource to become available, and a suspension-based approach, i.e. the task relinquishes the processor. A suspension-based approach can be viewed as a spin-based approach where the lowest priority on a core is used during spinning, similar to a non-preemptive spin-based approach where the highest priority on a core is used. By taking such a view, we previously provided a general model for spinning, where any arbitrary priority can be used for spinning, i.e. from the lowest to the highest priority on a core. Targeting partitioned fixed-priority preemptive scheduled multiprocessors and spin-based approaches that use a fixed priority for spinning per core for all tasks, we aim at increasing the schedulability of multiprocessor systems by using the spin-lock priority per core as parameter. In this paper, we present (i) a generalization of the traditional worst-case response-time analysis for non-preemptive spin-based approaches addressing an arbitrary but fixed spin-lock priority per core, (ii) an optimal spin-lock priority assignment (OSPA) algorithm per core, i.e. an algorithm that will find a fixed spin-lock priority per core that will make the system schedulable, whenever such an assignment exists and, (iii) comparative evaluations of the OSPA algorithm with the spin-based and suspension-based approaches where OSPA showed up to 38% improvement compared to both approaches.
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| 8. |
- Aglianò, Simone, et al.
(författare)
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Resource Management and Control in Virtualized SDN Networks
- 2018
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Ingår i: CSI International Symposium on Real-Time and Embedded Systems and Technologies REST'18. - 9781538614754 ; , s. 47-53
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Konferensbidrag (refereegranskat)abstract
- Software defined networking and network virtual-ization are widely considered promising techniques for reducing the complexity of network management in many contexts that require high Quality of Service (QoS) and the support for heterogeneous architectures. In this paper we address a network architecture, here called a virtualized SDN network, that combines the benefits of SDN and virtualization. To cope with the demand for efficiently sharing a platform among several services, here a resource management mechanism to reserve and control network resources among various services in the virtualized SDN networks is proposed. The mechanism is implemented on an SDN controller and a set of experiments show the effectiveness of the proposed approach.
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| 9. |
- Al-Dulaimy, Auday, et al.
(författare)
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Fault Tolerance in Cloud Manufacturing : An Overview
- 2023
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Ingår i: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST. - : Springer Science and Business Media Deutschland GmbH. - 9783031318900 ; , s. 89-101
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Konferensbidrag (refereegranskat)abstract
- Utilizing edge and cloud computing to empower the profitability of manufacturing is drastically increasing in modern industries. As a result of that, several challenges have raised over the years that essentially require urgent attention. Among these, coping with different faults in edge and cloud computing and recovering from permanent and temporary faults became prominent issues to be solved. In this paper, we focus on the challenges of applying fault tolerance techniques on edge and cloud computing in the context of manufacturing and we investigate the current state of the proposed approaches by categorizing them into several groups. Moreover, we identify critical gaps in the research domain as open research directions. © 2023, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.
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| 10. |
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