| 8051. |
- Inam, Rafia, 1974-, et al.
(författare)
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Bandwidth Measurement using Performance Counters for Predictable Multicore Software
- 2012
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Ingår i: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA 2012. ; , s. Article number: 6489714-
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Memory contention is one of the largest sources of inter-core interference in statically partitioned multicore systems, and the contention reduces the overall performance of applications and causes unpredictable execution-times. A first step in achieving predictable execution is to accurately measure the amount of consumed memory bandwidth for each application. Such measurements can be used to track down bottlenecks, provide better partitioning among cores, and ultimately be used to arbitrate and police access to the memory bus. We propose to use hardware performance counters to continuously track the memory-bandwidth consumed by different applications executing in parallel. In this paper we describe ongoing efforts exploring suitable performance counters on core-level and on system-on-chip level for the 8-core Freescale P4080 processor. The aim is to accurately and efficiently track consumed memory bandwidth per application; with the final goal to use these measurements to improve predictability of multicore real-time software.
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| 8052. |
- Inam, Rafia, et al.
(författare)
-
Combating unpredictability in multicores through the multi-resource server
- 2014
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Ingår i: 19th IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2014. - 9781479948468 ; , s. Article number 7005063-
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Konferensbidrag (refereegranskat)abstract
- In this paper we present challenges that hinder the predictable integration and execution of real-time applications on multicore platforms. We investigate how shared resources, like CPU, memory-bus bandwidth, caches, and memory cause unpredictability and interference. We propose to adapt the traditional server-based scheduling approach on the multicore platforms with additional resource-reservations to control the shared access to such resources and present the multi-resource server as a solution such that the execution of real-time applications becomes predictable.
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| 8053. |
- Inam, Rafia, et al.
(författare)
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Compositional Analysis for the Multi-Resource Server
- 2015
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Ingår i: 20th IEEE International Conference on Emerging Technologies and Factory Automation ETFA'15. - Luxembourg, Luxemburg : IEEE. ; , s. Article number 7301431-
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Konferensbidrag (refereegranskat)abstract
- The Multi-Resource Server (MRS) technique has been proposed to enable predictable execution of memory intensive real-time applications on COTS multi-core platforms. It uses resource reservation approaches in the context of CPUbandwidth and memory-bus bandwidth reservations to bound the interference between the applications running on the same core as well as between the applications running on different cores. In this paper we present a complete composable local and global schedulability analysis for the Multi-Resource Server technique. Based on the proposed analysis,we further provide an experimental study that investigates the behaviour of the MRS and identifies the factors that contribute mostly on the overall system performance.
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| 8054. |
- Inam, Rafia, 1974-, et al.
(författare)
-
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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| 8055. |
- Inam, Rafia, 1974-
(författare)
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Different Approaches used in Software Product Families
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The use of software in consumer products is growing tremendously in current era. Further the complexity of software in products is growing, diversity increasing, and the lead time is decreasing. To meet all these challenges software reuse in consumer products is the solution. This evolves the concepts of software product family, product population, and product lines. Three different approaches are used to integrate all software within hardware. These three approaches are Integration-Oriented platform, Hierarchal and Composition-Oriented. The integration-oriented approach is a classical approach used for many years in industry but unable to meet the challenges of todays increased usage. Hierarchical and Composition-Oriented approaches are popular now-a-days to meet the challenges of industry.
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| 8056. |
- 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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| 8057. |
- Inam, Rafia, 1974-
(författare)
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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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| 8058. |
- Inam, Rafia, et al.
(författare)
-
Hierarchical Scheduling Framework Implementation in FreeRTOS
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report presents the implementation of hierarchical scheduling framework HSF on an open source real-time operating system FreeRTOS to support the temporal isolation of a number of real-time components (or applications) onto a single processor. The goal is to achieve predictable integration and reusability of independently developed components or tasks. It presents the initial results of the HSF implementation by running it on an AVR 32-bit board EVK1100. It addresses the fixed-priority preemptive scheduling at both global and local scheduling levels. It describes the detailed design of HSF with the emphasis of doing minimal changes to the underlying FreeRTOS kernel and keeping its API intact. Finally it provides (and compares) the results for the performance measures of periodic and deferrable servers with respect to the overhead of the implementation. Index Terms: real-time systems; hierarchical scheduling framework; fixed-priority scheduling
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| 8059. |
- Inam, Rafia, 1974-, et al.
(författare)
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Implementing and Evaluating Communication- Strategies in the ProCom Component Technology
- 2012
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Ingår i: Acm Sigbed Review. - 1551-3688. ; 9:4, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents two strategies to support communication between real-time executable Runnable Virtual Node (RVN) components in the ProCom component technology. We describe the currently implemented server-based communication strategy which uses a dedicated server for communication. We compare the server-based technique with a direct (RVN-to-RVN) communication strategy. The paper also describes how these strategies could be evaluated for real-time performance, and the real-time analysis technologies needed to perform such an evaluation.
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| 8060. |
- Inam, Rafia, 1974-, et al.
(författare)
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Implementing Hierarchical Scheduling to support Multi-Mode System
- 2012
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Ingår i: 7th IEEE International Symposium on Industrial Embedded Systems (SIES) June 20 – June 22, 2012 Karlsruhe, Germany, Conference Proceedings. - Karlsruhe, Germany. ; , s. 319-322
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Konferensbidrag (refereegranskat)abstract
- Multi-mode embedded real-time systems exhibit a specific behavior for each mode and upon a mode-change request, the task-set and timing interfaces of the system need to be changed. Hierarchical Scheduling Framework (HSF) is a known technique to partition the CPU time into a number of hierarchically divided subsystems each consists of its own task set. We propose to implement a multi-mode system using a two-level HSF and provide a skeleton (framework) for an adaptive HSFs supporting multi-modes. Upon a mode-change request, the timing interface of each subsystem is changed, thus making the hierarchical scheduling adaptive in nature. We address the main goals for the implementation and describe the initial design details of Multi-Mode Adaptive Hierarchical Scheduling Framework (MMAHSF) with the emphasis of doing minimal changes to the underlying kernel.
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