88 research outputs found
Zuverlässige und Energieeffiziente gemischt-kritische Echtzeit On-Chip Systeme
Multi- and many-core embedded systems are increasingly becoming the target for many applications that require high performance under varying conditions. A resulting challenge is the control, and reliable operation of such complex multiprocessing architectures under changes, e.g., high temperature and degradation. In mixed-criticality systems where many applications with varying criticalities are consolidated on the same execution platform, fundamental isolation requirements to guarantee non-interference of critical functions are crucially important. While Networks-on-Chip (NoCs) are the prevalent solution to provide scalable and efficient interconnects for the multiprocessing architectures, their associated energy consumption has immensely increased. Specifically, hard real-time NoCs must manifest limited energy consumption as thermal runaway in such a core shared resource jeopardizes the whole system guarantees. Thus, dynamic energy management of NoCs, as opposed to the related work static solutions, is highly necessary to save energy and decrease temperature, while preserving essential temporal requirements. In this thesis, we introduce a centralized management to provide energy-aware NoCs for hard real-time systems. The design relies on an energy control network, developed on top of an existing switch arbitration network to allow isolation between energy optimization and data transmission. The energy control layer includes local units called Power-Aware NoC controllers that dynamically optimize NoC energy depending on the global state and applications’ temporal requirements. Furthermore, to adapt to abnormal situations that might occur in the system due to degradation, we extend the concept of NoC energy control to include the entire system scope. That is, online resource management employing hierarchical control layers to treat system degradation (imminent core failures) is supported. The mechanism applies system reconfiguration that involves workload migration. For mixed-criticality systems, it allows flexible boundaries between safety-critical and non-critical subsystems to safely apply the reconfiguration, preserving fundamental safety requirements and temporal predictability. Simulation and formal analysis-based experiments on various realistic usecases and benchmarks are conducted showing significant improvements in NoC energy-savings and in treatment of system degradation for mixed-criticality systems improving dependability over the status quo.Eingebettete Many- und Multi-core-Systeme werden zunehmend das Ziel für Anwendungen, die hohe Anfordungen unter unterschiedlichen Bedinungen haben. Für solche hochkomplexed Multi-Prozessor-Systeme ist es eine grosse Herausforderung zuverlässigen Betrieb sicherzustellen, insbesondere wenn sich die Umgebungseinflüsse verändern. In Systeme mit gemischter Kritikalität, in denen viele Anwendungen mit unterschiedlicher Kritikalität auf derselben Ausführungsplattform bedient werden müssen, sind grundlegende Isolationsanforderungen zur Gewährleistung der Nichteinmischung kritischer Funktionen von entscheidender Bedeutung. Während On-Chip Netzwerke (NoCs) häufig als skalierbare Verbindung für die Multiprozessor-Architekturen eingesetzt werden, ist der damit verbundene Energieverbrauch immens gestiegen. Daher sind dynamische Plattformverwaltungen, im Gegensatz zu den statischen, zwingend notwendig, um ein System an die oben genannten Veränderungen anzupassen und gleichzeitig Timing zu gewährleisten. In dieser Arbeit entwickeln wir energieeffiziente NoCs für harte Echtzeitsysteme. Das Design basiert auf einem Energiekontrollnetzwerk, das auf einem bestehenden Switch-Arbitration-Netzwerk entwickelt wurde, um eine Isolierung zwischen Energieoptimierung und Datenübertragung zu ermöglichen. Die Energiesteuerungsschicht umfasst lokale Einheiten, die als Power-Aware NoC-Controllers bezeichnet werden und die die NoC-Energie in Abhängigkeit vom globalen Zustand und den zeitlichen Anforderungen der Anwendungen optimieren. Darüber hinaus wird das Konzept der NoC-Energiekontrolle zur Anpassung an Anomalien, die aufgrund von Abnutzung auftreten können, auf den gesamten Systemumfang ausgedehnt. Online- Ressourcenverwaltungen, die hierarchische Kontrollschichten zur Behandlung Abnutzung (drohender Kernausfälle) einsetzen, werden bereitgestellt. Bei Systemen mit gemischter Kritikalität erlaubt es flexible Grenzen zwischen sicherheitskritischen und unkritischen Subsystemen, um die Rekonfiguration sicher anzuwenden, wobei grundlegende Sicherheitsanforderungen erhalten bleiben und Timing Vorhersehbarkeit. Experimente werden auf der Basis von Simulationen und formalen Analysen zu verschiedenen realistischen Anwendungsfallen und Benchmarks durchgeführt, die signifikanten Verbesserungen bei On-Chip Netzwerke-Energieeinsparungen und bei der Behandlung von Abnutzung für Systeme mit gemischter Kritikalität zur Verbesserung die Systemstabilität gegenüber dem bisherigen Status quo zeigen
Design and Programming Methods for Reconfigurable Multi-Core Architectures using a Network-on-Chip-Centric Approach
A current trend in the semiconductor industry is the use of Multi-Processor Systems-on-Chip (MPSoCs) for a wide variety of applications such as image processing, automotive, multimedia, and robotic systems. Most applications gain performance advantages by executing parallel tasks on multiple processors due to the inherent parallelism. Moreover, heterogeneous structures provide high performance/energy efficiency, since application-specific processing elements (PEs) can be exploited. The increasing number of heterogeneous PEs leads to challenging communication requirements. To overcome this challenge, Networks-on-Chip (NoCs) have emerged as scalable on-chip interconnect. Nevertheless, NoCs have to deal with many design parameters such as virtual channels, routing algorithms and buffering techniques to fulfill the system requirements.
This thesis highly contributes to the state-of-the-art of FPGA-based MPSoCs and NoCs. In the following, the three major contributions are introduced.
As a first major contribution, a novel router concept is presented that efficiently utilizes communication times by performing sequences of arithmetic operations on the data that is transferred. The internal input buffers of the routers are exchanged with processing units that are capable of executing operations. Two different architectures of such processing units are presented. The first architecture provides multiply and accumulate operations which are often used in signal processing applications. The second architecture introduced as Application-Specific Instruction Set Routers (ASIRs) contains a processing unit capable of executing any operation and hence, it is not limited to multiply and accumulate operations. An internal processing core located in ASIRs can be developed in C/C++ using high-level synthesis.
The second major contribution comprises application and performance explorations of the novel router concept. Models that approximate the achievable speedup and the end-to-end latency of ASIRs are derived and discussed to show the benefits in terms of performance. Furthermore, two applications using an ASIR-based MPSoC are implemented and evaluated on a Xilinx Zynq SoC. The first application is an image processing algorithm consisting of a Sobel filter, an RGB-to-Grayscale conversion, and a threshold operation. The second application is a system that helps visually impaired people by navigating them through unknown indoor environments. A Light Detection and Ranging (LIDAR) sensor scans the environment, while Inertial Measurement Units (IMUs) measure the orientation of the user to generate an audio signal that makes the distance as well as the orientation of obstacles audible. This application consists of multiple parallel tasks that are mapped to an ASIR-based MPSoC. Both applications show the performance advantages of ASIRs compared to a conventional NoC-based MPSoC. Furthermore, dynamic partial reconfiguration in terms of relocation and security aspects are investigated.
The third major contribution refers to development and programming methodologies of NoC-based MPSoCs. A software-defined approach is presented that combines the design and programming of heterogeneous MPSoCs. In addition, a Kahn-Process-Network (KPN) –based model is designed to describe parallel applications for MPSoCs using ASIRs. The KPN-based model is extended to support not only the mapping of tasks to NoC-based MPSoCs but also the mapping to ASIR-based MPSoCs. A static mapping methodology is presented that assigns tasks to ASIRs and processors for a given KPN-model. The impact of external hardware components such as sensors, actuators and accelerators connected to the processors is also discussed which makes the approach of high interest for embedded systems
CROSS-LAYER DESIGN, OPTIMIZATION AND PROTOTYPING OF NoCs FOR THE NEXT GENERATION OF HOMOGENEOUS MANY-CORE SYSTEMS
This thesis provides a whole set of design methods to enable and manage the
runtime heterogeneity of features-rich industry-ready Tile-Based Networkon-
Chips at different abstraction layers (Architecture Design, Network Assembling,
Testing of NoC, Runtime Operation). The key idea is to maintain
the functionalities of the original layers, and to improve the performance
of architectures by allowing, joint optimization and layer coordinations. In
general purpose systems, we address the microarchitectural challenges by codesigning
and co-optimizing feature-rich architectures. In application-specific
NoCs, we emphasize the event notification, so that the platform is continuously
under control. At the network assembly level, this thesis proposes a
Hold Time Robustness technique, to tackle the hold time issue in synchronous
NoCs. At the network architectural level, the choice of a suitable synchronization
paradigm requires a boost of synthesis flow as well as the coexistence
with the DVFS. On one hand this implies the coexistence of mesochronous
synchronizers in the network with dual-clock FIFOs at network boundaries.
On the other hand, dual-clock FIFOs may be placed across inter-switch links
hence removing the need for mesochronous synchronizers. This thesis will
study the implications of the above approaches both on the design flow and
on the performance and power quality metrics of the network. Once the manycore
system is composed together, the issue of testing it arises. This thesis
takes on this challenge and engineers various testing infrastructures. At the
upper abstraction layer, the thesis addresses the issue of managing the fully
operational system and proposes a congestion management technique named
HACS. Moreover, some of the ideas of this thesis will undergo an FPGA
prototyping. Finally, we provide some features for emerging technology by
characterizing the power consumption of Optical NoC Interfaces
Encryption AXI Transaction Core for Enhanced FPGA Security
The current hot topic in cyber-security is not constrained to software layers. As attacks on electronic circuits have become more usual and dangerous, hardening digital System-on-Chips has become crucial. This article presents a novel electronic core to encrypt and decrypt data between two digital modules through an Advanced eXtensible Interface (AXI) connection. The core is compatible with AXI and is based on a Trivium stream cipher. Its implementation has been tested on a Zynq platform. The core prevents unauthorized data extraction by encrypting data on the fly. In addition, it takes up a small area—242 LUTs—and, as the core’s AXI to AXI path is fully combinational, it does not interfere with the system’s overall performance, with a maximum AXI clock frequency of 175 MHz.This work has been supported within the fund for research groups of the Basque university system IT1440-22 by the Department of Education and within the PILAR ZE-2020/00022 and COMMUTE ZE-2021/00931 projects by the Hazitek program, both of the Basque Government, the latter also by the Ministerio de Ciencia e InnovaciĂłn of Spain through the Centro para el Desarrollo TecnolĂłgico Industrial (CDTI) within the project IDI-20201264 and IDI-20220543 and through the Fondo Europeo de Desarrollo Regional 2014–2020 (FEDER funds)
Proceedings of the 5th International Workshop on Reconfigurable Communication-centric Systems on Chip 2010 - ReCoSoC\u2710 - May 17-19, 2010 Karlsruhe, Germany. (KIT Scientific Reports ; 7551)
ReCoSoC is intended to be a periodic annual meeting to expose and discuss gathered expertise as well as state of the art research around SoC related topics through plenary invited papers and posters. The workshop aims to provide a prospective view of tomorrow\u27s challenges in the multibillion transistor era, taking into account the emerging techniques and architectures exploring the synergy between flexible on-chip communication and system reconfigurability
Self-adaptivity of applications on network on chip multiprocessors: the case of fault-tolerant Kahn process networks
Technology scaling accompanied with higher operating frequencies and the ability to integrate more functionality in the same chip has been the driving force behind delivering higher performance computing systems at lower costs. Embedded computing systems, which have been riding the same wave of success, have evolved into complex architectures encompassing a high number of cores interconnected by an on-chip network (usually identified as Multiprocessor System-on-Chip). However these trends are hindered by issues that arise as technology scaling continues towards deep submicron scales. Firstly, growing complexity of these systems and the variability introduced by process technologies make it ever harder to perform a thorough optimization of the system at design time. Secondly, designers are faced with a reliability wall that emerges as age-related degradation reduces the lifetime of transistors, and as the probability of defects escaping post-manufacturing testing is increased. In this thesis, we take on these challenges within the context of streaming applications running in network-on-chip based parallel (not necessarily homogeneous) systems-on-chip that adopt the no-remote memory access model. In particular, this thesis tackles two main problems: (1) fault-aware online task remapping, (2) application-level self-adaptation for quality management. For the former, by viewing fault tolerance as a self-adaptation aspect, we adopt a cross-layer approach that aims at graceful performance degradation by addressing permanent faults in processing elements mostly at system-level, in particular by exploiting redundancy available in multi-core platforms. We propose an optimal solution based on an integer linear programming formulation (suitable for design time adoption) as well as heuristic-based solutions to be used at run-time. We assess the impact of our approach on the lifetime reliability. We propose two recovery schemes based on a checkpoint-and-rollback and a rollforward technique. For the latter, we propose two variants of a monitor-controller- adapter loop that adapts application-level parameters to meet performance goals. We demonstrate not only that fault tolerance and self-adaptivity can be achieved in embedded platforms, but also that it can be done without incurring large overheads. In addressing these problems, we present techniques which have been realized (depending on their characteristics) in the form of a design tool, a run-time library or a hardware core to be added to the basic architecture
Energy-Efficient and Reliable Computing in Dark Silicon Era
Dark silicon denotes the phenomenon that, due to thermal and power constraints, the fraction of transistors that can operate at full frequency is decreasing in each technology generation. Moore’s law and Dennard scaling had been backed and coupled appropriately for five decades to bring commensurate exponential performance via single core and later muti-core design. However, recalculating Dennard scaling for recent small technology sizes shows that current ongoing multi-core growth is demanding exponential thermal design power to achieve linear performance increase. This process hits a power wall where raises the amount of dark or dim silicon on future multi/many-core chips more and more. Furthermore, from another perspective, by increasing the number of transistors on the area of a single chip and susceptibility to internal defects alongside aging phenomena, which also is exacerbated by high chip thermal density, monitoring and managing the chip reliability before and after its activation is becoming a necessity. The proposed approaches and experimental investigations in this thesis focus on two main tracks: 1) power awareness and 2) reliability awareness in dark silicon era, where later these two tracks will combine together. In the first track, the main goal is to increase the level of returns in terms of main important features in chip design, such as performance and throughput, while maximum power limit is honored. In fact, we show that by managing the power while having dark silicon, all the traditional benefits that could be achieved by proceeding in Moore’s law can be also achieved in the dark silicon era, however, with a lower amount. Via the track of reliability awareness in dark silicon era, we show that dark silicon can be considered as an opportunity to be exploited for different instances of benefits, namely life-time increase and online testing. We discuss how dark silicon can be exploited to guarantee the system lifetime to be above a certain target value and, furthermore, how dark silicon can be exploited to apply low cost non-intrusive online testing on the cores. After the demonstration of power and reliability awareness while having dark silicon, two approaches will be discussed as the case study where the power and reliability awareness are combined together. The first approach demonstrates how chip reliability can be used as a supplementary metric for power-reliability management. While the second approach provides a trade-off between workload performance and system reliability by simultaneously honoring the given power budget and target reliability
Driving the Network-on-Chip Revolution to Remove the Interconnect Bottleneck in Nanoscale Multi-Processor Systems-on-Chip
The sustained demand for faster, more powerful chips has been met by the
availability of chip manufacturing processes allowing for the integration of increasing
numbers of computation units onto a single die. The resulting outcome,
especially in the embedded domain, has often been called SYSTEM-ON-CHIP
(SoC) or MULTI-PROCESSOR SYSTEM-ON-CHIP (MP-SoC).
MPSoC design brings to the foreground a large number of challenges, one of
the most prominent of which is the design of the chip interconnection. With a
number of on-chip blocks presently ranging in the tens, and quickly approaching
the hundreds, the novel issue of how to best provide on-chip communication
resources is clearly felt.
NETWORKS-ON-CHIPS (NoCs) are the most comprehensive and scalable
answer to this design concern. By bringing large-scale networking concepts to
the on-chip domain, they guarantee a structured answer to present and future
communication requirements. The point-to-point connection and packet switching
paradigms they involve are also of great help in minimizing wiring overhead
and physical routing issues. However, as with any technology of recent inception,
NoC design is still an evolving discipline. Several main areas of interest
require deep investigation for NoCs to become viable solutions:
• The design of the NoC architecture needs to strike the best tradeoff among
performance, features and the tight area and power constraints of the onchip
domain.
• Simulation and verification infrastructure must be put in place to explore,
validate and optimize the NoC performance.
• NoCs offer a huge design space, thanks to their extreme customizability in
terms of topology and architectural parameters. Design tools are needed
to prune this space and pick the best solutions.
• Even more so given their global, distributed nature, it is essential to evaluate
the physical implementation of NoCs to evaluate their suitability for
next-generation designs and their area and power costs.
This dissertation performs a design space exploration of network-on-chip architectures,
in order to point-out the trade-offs associated with the design of
each individual network building blocks and with the design of network topology
overall. The design space exploration is preceded by a comparative analysis
of state-of-the-art interconnect fabrics with themselves and with early networkon-
chip prototypes. The ultimate objective is to point out the key advantages
that NoC realizations provide with respect to state-of-the-art communication
infrastructures and to point out the challenges that lie ahead in order to make
this new interconnect technology come true. Among these latter, technologyrelated
challenges are emerging that call for dedicated design techniques at all
levels of the design hierarchy. In particular, leakage power dissipation, containment
of process variations and of their effects. The achievement of the above
objectives was enabled by means of a NoC simulation environment for cycleaccurate
modelling and simulation and by means of a back-end facility for the
study of NoC physical implementation effects. Overall, all the results provided
by this work have been validated on actual silicon layout
Design and Implementation of High QoS 3D-NoC using Modified Double Particle Swarm Optimization on FPGA
One technique to overcome the exponential growth bottleneck is to increase the number of cores on a processor, although having too many cores might cause issues including chip overheating and communication blockage. The problem of the communication bottleneck on the chip is presently effectively resolved by networks-on-chip (NoC). A 3D stack of chips is now possible, thanks to recent developments in IC manufacturing techniques, enabling to reduce of chip area while increasing chip throughput and reducing power consumption. The automated process associated with mapping applications to form three-dimensional NoC architectures is a significant new path in 3D NoC research. This work proposes a 3D NoC partitioning approach that can identify the 3D NoC region that has to be mapped. A double particle swarm optimization (DPSO) inspired algorithmic technique, which may combine the characteristics having neighbourhood search and genetic architectures, also addresses the challenge of a particle swarm algorithm descending into local optimal solutions. Experimental evidence supports the claim that this hybrid optimization algorithm based on Double Particle Swarm Optimisation outperforms the conventional heuristic technique in terms of output rate and loss in energy. The findings demonstrate that in a network of the same size, the newly introduced router delivers the lowest loss on the longest path. Three factors, namely energy, latency or delay, and throughput, are compared between the suggested 3D mesh ONoC and its 2D version. When comparing power consumption between 3D ONoC and its electronic and 2D equivalents, which both have 512 IP cores, it may save roughly 79.9% of the energy used by the electronic counterpart and 24.3% of the energy used by the latter. The network efficiency of the 3D mesh ONoC is simulated by DPSO in a variety of configurations. The outcomes also demonstrate an increase in performance over the 2D ONoC. As a flexible communication solution, Network-On-Chips (NoCs) have been frequently employed in the development of multiprocessor system-on-chips (MPSoCs). By outsourcing their communication activities, NoCs permit on-chip Intellectual Property (IP) cores to communicate with one another and function at a better level. The important components in assigning application duties, distributing the work to the IPs, and coordinating communication among them are mapping and scheduling methods. This study aims to present an entirely advanced form of research in the area of 3D NoC mapping and scheduling applications, grouping the results according to various parameters and offering several suggestions for further research
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