| 41. |
- Afshar, Sara, et al.
(författare)
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Towards Resource Sharing under Multiprocessor Semi-Partitioned Scheduling
- 2012
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Ingår i: 7th IEEE International Symposium on Industrial Embedded Systems (SIES'12). - : IEEE. - 9781467326834 - 9781467326858 ; , s. 315-318
-
Konferensbidrag (refereegranskat)abstract
- Semi-partitioned scheduling has been the subject of recent interest, compared with conventional global and partitioned scheduling algorithms for multiprocessors, due to better utilization results. In semi-partitioned scheduling most tasks are assigned to fixed processors while a low number of tasks are split up and allocated to different processors. Various techniques have recently been proposed to assign tasks in a semi-partitioned environment. However, an appropriate resource sharing mechanism for handling the resource requests between tasks in semi-partitioned scheduling has not yet been investigated. In this paper we propose two methods for handling resource sharing under semi-partitioned scheduling in multiprocessor platforms. The main challenge is to handle the resource requests of tasks that are split over multiple processors.
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| 42. |
- Afshar, Sara Zargari, et al.
(författare)
-
An optimal spin-lock priority assignment algorithm for real-time multi-core systems
- 2017
-
Ingår i: The 23th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications RTCSA'17.
-
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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| 43. |
- Al-Dulaimy, Auday, et al.
(författare)
-
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
-
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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| 44. |
- Al-Dulaimy, Auday, et al.
(författare)
-
LOOPS : A Holistic Control Approach for Resource Management in Cloud Computing
- 2021
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Ingår i: ICPE 2021 - Proceedings of the ACM/SPEC International Conference on Performance Engineering. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450381949 ; , s. 117-124
-
Konferensbidrag (refereegranskat)abstract
- In cloud computing model, resource sharing introduces major benefits for improving resource utilization and total cost of ownership, but it can create technical challenges on the running performance. In practice, orchestrators are required to allocate sufficient physical resources to each Virtual Machine (VM) to meet a set of predefined performance goals. To ensure a specific service level objective, the orchestrator needs to be equipped with a dynamic tool for assigning computing resources to each VM, based on the run-Time state of the target environment. To this end, we present LOOPS, a multi-loop control approach, to allocate resources to VMs based on the service level agreement (SLA) requirements and the run-Time conditions. LOOPS is mainly composed of one essential unit to monitor VMs, and three control levels to allocate resources to VMs based on requests from the essential node. A tailor-made controller is proposed with each level to regulate contention among collocated VMs, to reallocate resources if required, and to migrate VMs from one host to another. The three levels work together to meet the required SLA. The experimental results have shown that the proposed approach can meet applications' performance goals by assigning the resources required by cloud-based applications.
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| 45. |
- Al-Furoukh, Natalie, et al.
(författare)
-
ClpX stimulates the mitochondrial unfolded protein response (UPRmt) in mammalian cells
- 2015
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Ingår i: Biochimica et Biophysica Acta. Molecular Cell Research. - : Elsevier BV. - 0167-4889 .- 1879-2596. ; 1853:10, s. 2580-2591
-
Tidskriftsartikel (refereegranskat)abstract
- Proteostasis is crucial for life and maintained by cellular chaperones and proteases. One major mitochondrial protease is the ClpXP complex, which is comprised of a catalytic ClpX subunit and a proteolytic ClpP subunit. Based on two separate observations, we hypothesized that ClpX may play a leading role in the cellular function of ClpXP. Therefore, we analyzed the effect of ClpX overexpression on a myoblast proteome by quantitative proteomics. ClpX overexpression results in the upregulation of markers of the mitochondria( proteostasis pathway, known as the "mitochondrial unfolded protein response" (UPRmt). Although this pathway is described in detail in Caenorhabditis elegans, it is not clear whether it is conserved in mammals. Therefore, we compared features of the classical nematode UPRmt with our mammalian ClpX-triggered UPRmt dataset. We show that they share the same retrograde mitochondria-to-nucleus signaling pathway that involves the key UPRmt transcription factor CHOP (also known as Ddit3, CEBPZ or GADD153). In conclusion, our data confirm the existence of a mammalian UPRmt that has great similarity to the C elegans pathway. Furthermore, our results illustrate that ClpX overexpression is a good and simple model to study the underlying mechanisms of the UPRmt in mammalian cells.
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| 46. |
- Alhashimi, Anas, et al.
(författare)
-
Change-Point and Model Estimation with Heteroskedastic Noise and Unknown Model Structure
- 2023
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Ingår i: Int. Conf. Control, Decis. Inf. Technol., CoDIT. - : Institute of Electrical and Electronics Engineers Inc.. - 9798350311402 ; , s. 2126-2132
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the problem of modeling time-series as a process generated through (i) switching between several independent sub-models; (ii) where each sub-model has heteroskedastic noise, and (iii) a polynomial bias, describing nonlinear dependency on system input. First, we propose a generic nonlinear and heteroskedastic statistical model for the process. Then, we design Maximum Likelihood (ML) parameters estimation method capable of handling heteroscedasticity and exploiting constraints on model structure. We investigate solving the intractable ML optimization using population-based stochastic numerical methods. We then find possible model change-points that maximize the likelihood without over-fitting measurement noise. Finally, we verify the usefulness of the proposed technique in a practically relevant case study, the execution-time of odometry estimation for a robot operating radar sensor, and evaluate the different proposed procedures using both simulations and field data.
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| 47. |
- Alhashimi, Anas, et al.
(författare)
-
Enhancing Sensor Attack Detection and Mitigating Sensor Compromise Impact in a Switching-Based Moving Target Defense
- 2024
-
Ingår i: 2024 European Control Conference, ECC 2024. - : Institute of Electrical and Electronics Engineers Inc.. - 9783907144107 ; , s. 2560-2567
-
Konferensbidrag (refereegranskat)abstract
- This study is based on a Moving Target Defence (MTD) algorithm designed to introduce uncertainty into the controller and another layer of uncertainty to intrusion detection. This randomness complicates the adversary's attempts to craft stealthy attacks while concurrently minimizing the impact of false-data injection attacks. Leveraging concepts from state observer design, the method establishes an optimization framework to determine the parameters of the random signals. These signals are strategically tuned to increase the detectability of stealthy attacks while reducing the deviation resulting from false data injection attempts. We propose here to use two different state observers and two associated MTD algorithms. The first one optimizes the parameters of the random signals to reduce the deviation resulting from false data injection attempts and maintain the stability of the closed-loop system with the desired level of performance. In contrast, the second one optimizes the parameters of the random signals to increase the detectability of stealthy attacks. Dividing the optimization problem into two separate optimization processes simplifies the search process and makes it possible to have higher values of the detection cost function. To illustrate the effectiveness of our approach, we present a case study involving a generic linear time-invariant system and compare the results with a recently published algorithm.
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| 48. |
- Ashjaei, Mohammad, et al.
(författare)
-
A Compact Approach to Clustered Master-Slave Ethernet Networks
- 2012
-
Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781467315739 ; , s. 157-160
-
Konferensbidrag (refereegranskat)abstract
- Ethernet switches are increasingly used in real-time distributed systems as a technical solution to guarantee the timeliness in communications. However, there are still limitations related to real-time behavior caused by the limited number of priority levels and the possibility of memory overruns with consequent message losses. These limitations can be eliminated using a master/slave technique such as proposed by the FTT paradigm. This led to the FTT-SE protocol that schedules transmissions centrally in a master node. While this protocol has already been well studied and investigated for small networks with a single switch, its extension to larger networks is still an open issue. In this paper we propose a compact clustered solution to scale the FTT-SE protocol to networks of multiple switches by organizing the network in sub-networks composed of one master and one switch each and which can be connected directly, without bridges. This paper also shows how the timeliness of the traffic can still be enforced. The validation is currently on-going.
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| 49. |
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| 50. |
- Ashjaei, Mohammad, et al.
(författare)
-
Dynamic reconfiguration in HaRTES switched ethernet networks
- 2016
-
Ingår i: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS. - 9781509023394
-
Konferensbidrag (refereegranskat)abstract
- The ability of reconfiguring a system during runtime is essential for dynamic real-time applications in which resource usage is traded online for quality of service. The HaRTES switch, which is a modified Ethernet switch, holds this ability for the network resource, and at the same time it provides hard real-time support for both periodic and sporadic traffic. Although the HaRTES switch technologically caters this ability, a protocol to actually perform the dynamic reconfiguration is missing in multi-hop HaRTES networks. In this paper we introduce such a protocol that is compatible with the traffic scheduling method used in the architecture. We prove the correctness of the protocol using a model checking technique. Moreover, we conduct a set of simulation experiments to show the performance of the protocol and we also show that the reconfiguration process is terminated within a bounded time.
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