12,575 research outputs found
An On-line BIST RAM Architecture with Self Repair Capabilities
The emerging field of self-repair computing is expected to have a major impact on deployable systems for space missions and defense applications, where high reliability, availability, and serviceability are needed. In this context, RAM (random access memories) are among the most critical components. This paper proposes a built-in self-repair (BISR) approach for RAM cores. The proposed design, introducing minimal and technology-dependent overheads, can detect and repair a wide range of memory faults including: stuck-at, coupling, and address faults. The test and repair capabilities are used on-line, and are completely transparent to the external user, who can use the memory without any change in the memory-access protocol. Using a fault-injection environment that can emulate the occurrence of faults inside the module, the effectiveness of the proposed architecture in terms of both fault detection and repairing capability was verified. Memories of various sizes have been considered to evaluate the area-overhead introduced by this proposed architectur
On the analysis of the timing behaviour of time randomised caches
Time Randomised caches (TRc), which can be implemented at hardware level or with
software means on conventional deterministic cache designs, have been proposed for
real-time systems as key enablers for Probabilistic Timing Analysis (PTA) and in
particular its measurement-based variant: Measurement-Based Probabilistic Timing
Analysis (MBPTA). A key parameter of MBPTA is the number of runs required to
ensure representativity of the execution time measurements taken at analysis time
with respect to execution times that can occur during system deployment, so that
MBPTA can trustworthily be applied.
In this thesis, we propose several methods to determine whether the number of
observations taken at analysis, as part of the normal MBPTA application process,
capture the cache events significantly impacting execution time and Worst-Case Execution
Time (WCET). If this is not the case, our techniques provide the user with the
number of extra runs required so that cache events are captured ensuring trustworthiness
on MBPTA provided WCET estimates. Our techniques have been evaluated
using a set of synthetic benchmarks and a real avionics application
Run-time Spatial Mapping of Streaming Applications to Heterogeneous Multi-Processor Systems
In this paper, we define the problem of spatial mapping. We present reasons why performing spatial mappings at run-time is both necessary and desirable. We propose what isâto our knowledgeâthe first attempt at a formal description of spatial mappings for the embedded real-time streaming application domain. Thereby, we introduce criteria for a qualitative comparison of these spatial mappings. As an illustration of how our formalization relates to practice, we relate our own spatial mapping algorithm to the formal model
From Traditional Adaptive Data Caching to Adaptive Context Caching: A Survey
Context data is in demand more than ever with the rapid increase in the
development of many context-aware Internet of Things applications. Research in
context and context-awareness is being conducted to broaden its applicability
in light of many practical and technical challenges. One of the challenges is
improving performance when responding to large number of context queries.
Context Management Platforms that infer and deliver context to applications
measure this problem using Quality of Service (QoS) parameters. Although
caching is a proven way to improve QoS, transiency of context and features such
as variability, heterogeneity of context queries pose an additional real-time
cost management problem. This paper presents a critical survey of
state-of-the-art in adaptive data caching with the objective of developing a
body of knowledge in cost- and performance-efficient adaptive caching
strategies. We comprehensively survey a large number of research publications
and evaluate, compare, and contrast different techniques, policies, approaches,
and schemes in adaptive caching. Our critical analysis is motivated by the
focus on adaptively caching context as a core research problem. A formal
definition for adaptive context caching is then proposed, followed by
identified features and requirements of a well-designed, objective optimal
adaptive context caching strategy.Comment: This paper is currently under review with ACM Computing Surveys
Journal at this time of publishing in arxiv.or
A Switch Architecture for Real-Time Multimedia Communications
In this paper we present a switch that can be used to transfer multimedia type of trafJic. The switch provides a guaranteed throughput and a bounded latency. We focus on the design of a prototype Switching Element using the new technology opportunities being offered today. The architecture meets the multimedia requirements but still has a low complexity and needs a minimum amount of hardware. A main item of this paper will be the background of the architectural design decisions made. These include the interconnection topology, buffer organization, routing and scheduling. The implementation of the switching fabric with FPGAs, allows us to experiment with switching mode, routing strategy and scheduling policy in a multimedia environment. The witching elements are interconnected in a Kautz topology. Kautz graphs have interesting properties such as: a small diametec the degree is independent of the network size, the network is fault-tolerant and has a simple routing algorithm
Multi-core devices for safety-critical systems: a survey
Multi-core devices are envisioned to support the development of next-generation safety-critical systems, enabling the on-chip integration of functions of different criticality. This integration provides multiple system-level potential benefits such as cost, size, power, and weight reduction. However, safety certification becomes a challenge and several fundamental safety technical requirements must be addressed, such as temporal and spatial independence, reliability, and diagnostic coverage. This survey provides a categorization and overview at different device abstraction levels (nanoscale, component, and device) of selected key research contributions that support the compliance with these fundamental safety requirements.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness under grant TIN2015-65316-P, Basque Government under grant KK-2019-00035 and the HiPEAC Network of Excellence. The Spanish Ministry of Economy and Competitiveness has also partially supported Jaume Abella under Ramon y Cajal postdoctoral fellowship (RYC-2013-14717).Peer ReviewedPostprint (author's final draft
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