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Section: New Results
Infrastructure-level support
We apply the results of the previous axes of the team's activity to a range of infrastructures of different natures, but sharing a transversal problem of reconfiguration control design. From this very diversity of validations and experiences, we draw a synthesis of the whole approach, towards a general view of Feedback Control as MAPE-K loop in Autonomic Computing [23], [22].
Autonomic Cloud and Big-Data systems
Participants : Soguy Mak Kare Gueye, Gwenaël Delaval, Eric Rutten.
Complex computing systems are increasingly self-adaptive, with an autonomic computing approach for their administration. Real systems require the co-existence of multiple autonomic management loops, each complex to design. However their uncoordinated co-existence leads to performance degradation and possibly to inconsistency. There is a need for methodological supports facilitating the coordination of multiple autonomic managers. To tackle this problem, we take a global view and underscore that Autonomic Management Systems (AMS) are intrinsically reactive, as they react to flows of monitoring data by emitting flows of reconfiguration actions. Therefore we propose a new approach for the design of AMSs, based on synchronous programming and discrete controller synthesis techniques. They provide us with high-level languages for modeling the system to manage, as well as means for statically guaranteeing the absence of logical coordination problems. Hence, they suit our main contribution, which is to obtain guarantees at design time about the absence of logical inconsistencies in the taken decisions. We detail our approach, illustrate it by designing an AMS for a realistic multi-tier application, and evaluate its practicality with an implementation [16].
We addressed these problems in the context of follow-ups of the ANR project Ctrl-Green, in cooperation with LIG (N. de Palma) in the framework of the PhD of S. Gueye [17] and the post-doc of N. Berthier.
Reconfiguration control in DPR FPGA
Participants : Soguy Mak Kare Gueye, Eric Rutten.
Dynamically reconfigurable hardware has been identified as a promising solution for the design of energy efficient embedded systems. However, its adoption is limited by the costly design effort including verification and validation, which is even more complex than for non dynamically reconfigurable systems. We worked on this topic in the context of a ensign environment, developed in the framework of the ANR project Famous, in cooperation with LabSticc in Lorient and Inria Lille (DaRT team). We proposed a tool-supported formal method to automatically design a correct-by-construction control of the reconfiguration. By representing system behaviors with automata, we exploit automated algorithms to synthesize controllers that safely enforce reconfiguration strategies formulated as properties to be satisfied by control. We design generic modeling patterns for a class of reconfigurable architectures, taking into account both hardware architecture and applications, as well as relevant control objectives. We validate our approach on two case studies implemented on FPGAs [3].
We are currently valorizing results in more publications [15], and extending the use of control techniques by evaluating the new tool ReaX developed at Inria Rennes (Sumo).
We are starting a new ANR project called HPeC, within which some of these topics will be extended, especially regarding hierarchical and modular control, and logico-numeric aspects.
Autonomic memory management in HPC
Participants : Naweiluo Zhou, Gwenaël Delaval, Bogdan Robu, Eric Rutten.
Parallel programs need to manage the time trade-off between synchronization and computation. A high parallelism may decrease computing time but meanwhile increase synchronization cost among threads. Software Transactional Memory (STM) has emerged as a promising technique, which bypasses locks, to address synchronization issues through transactions. A way to reduce conflicts is by adjusting the parallelism, as a suitable parallelism can maximize program performance. However, there is no universal rule to decide the best parallelism for a program from an offline view. Furthermore, an offline tuning is costly and error-prone. Hence, it becomes necessary to adopt a dynamical tuning-configuration strategy to better manage a STM system. Autonomic control techniques begin to receive attention in computing systems recently. Control technologies offer designers a framework of methods and techniques to build autonomic systems with well-mastered behaviors. The key idea of autonomic control is to implement feedback control loops to design safe, efficient and predictable controllers, which enable monitoring and adjusting controlled systems dynamically while keeping overhead low. We propose to design feedback control loops to automate the choice of parallelism at runtime and diminish program execution time [20], [24], [21]. It is then combined with another objective related to Thread Mapping Control [19]
In the context of the action-team HPES of the Labex Persyval-lab (https://persyval-lab.org/en/sites/hpes) (see 9.1), this work is performed in cooperation with LIG (J.F. Méhaut) in the framework of the PhD of N. Zhou [14].
Control of smart environments
Participants : Adja Sylla, Armando Ochoa, Eric Rutten, Stéphane Mocanu.
A service-oriented approach to smart home applications control with reactive programming
The need for adaptability in pervasive computing is growing, driven in part by the increasing number and variety of communication devices. In autonomic applications, however, the control architecture frequently becomes itself a complex system that needs to be adapted. Autonomic applications are often composed of multiple control loops ? each addressing a specific aspect ? whose execution needs to be coordinated for efficient and correct administration. We therefore propose to investigate the use of reactive control models with events and states to coordinate autonomic loops in service-oriented architectures. In this work, we illustrate our approach by integrating a controller based on discrete controller synthesis in an autonomic pervasive environment. The role of the controller is to influence the service-binding criteria of multiple control loops, while respecting logical constraints. In particular, we consider reconfiguration operations of known and dynamic service sets. This work constituted the M2R internship of Armando Ochoa, and was performed in cooperation with the Adele team at LIG, co-advised by E. Rutten and V. Lestideau, in the framework of the Labex Persyval-lab project CASE.
Another activity in this topic was the M2R internship of Ronak Feizimirkhani, co-advised by S. Mocanu and V. Lestideau, The context is the development of an application for a smart home in which automation devices are connected through a wireless communication protocol, Z-Wave, and controlled by a central controller, USB plug in. This involves methods and tools to design fail-safe controllers for autonomic, adaptive, reconfigurable computing systems by combining Computer Science and Control Theory techniques. For this purpose, it is necessary to access required information over the network, derive out a simplified model of the physical network, and then link it to the User interface application. According to the information achieved, there will be an estimation of the network diagnostics to find some probable solutions for. The final application is in a user media to do installing, maintaining or even optimizing the network and devices.
Rule-based specification of smart environments control
In the context of IoT applications like mart home environments, the rules for programming in the LINC framework are used as a flexible tool to govern the relations between sensors and actuators. Runtime coordination and formal analysis becomes a necessity to avoid side effects mainly when applications are critical. In cooperation with CEA LETI/DACLE, we are working on a case study for safe applications development in IoT and smart home environments.
New results from Section 7.1.2 are applied in case studies regarding smart environments (offices or homes) [18].