57 research outputs found
Modeling, Analysis, and Hard Real-time Scheduling of Adaptive Streaming Applications
In real-time systems, the application's behavior has to be predictable at
compile-time to guarantee timing constraints. However, modern streaming
applications which exhibit adaptive behavior due to mode switching at run-time,
may degrade system predictability due to unknown behavior of the application
during mode transitions. Therefore, proper temporal analysis during mode
transitions is imperative to preserve system predictability. To this end, in
this paper, we initially introduce Mode Aware Data Flow (MADF) which is our new
predictable Model of Computation (MoC) to efficiently capture the behavior of
adaptive streaming applications. Then, as an important part of the operational
semantics of MADF, we propose the Maximum-Overlap Offset (MOO) which is our
novel protocol for mode transitions. The main advantage of this transition
protocol is that, in contrast to self-timed transition protocols, it avoids
timing interference between modes upon mode transitions. As a result, any mode
transition can be analyzed independently from the mode transitions that
occurred in the past. Based on this transition protocol, we propose a hard
real-time analysis as well to guarantee timing constraints by avoiding
processor overloading during mode transitions. Therefore, using this protocol,
we can derive a lower bound and an upper bound on the earliest starting time of
the tasks in the new mode during mode transitions in such a way that hard
real-time constraints are respected.Comment: Accepted for presentation at EMSOFT 2018 and for publication in IEEE
Transactions on Computer-Aided Design of Integrated Circuits and Systems
(TCAD) as part of the ESWEEK-TCAD special issu
Thermodynamics of fluid elements in the context of saturated isothermal turbulence in molecular clouds
The presented paper is an attempt to investigate the dynamical states of an
hydrodynamical isothermal turbulent self-gravitating system using some powerful
tools of the classical thermodynamics. Our main assumption, inspired by the
work of Keto et al. (2020), is that turbulent kinetic energy can be substituted
for the macro-temperature of chaotic motion of fluid elements. As a proper
sample for our system we use a model of turbulent self-gravitating isothermal
molecular cloud which is at final stages of its life-cycle, when the dynamics
is nearly in steady state. Starting from this point, we write down the internal
energy for a physically small cloud's volume, and then using the first
principle of thermodynamics obtain in explicit form the entropy, free energy,
and Gibbs potential for this volume. Setting fiducial boundary conditions for
the latter system (small volume) we explore its stability as a grand canonical
ensemble. Searching for extrema of the Gibbs potential we obtain conditions for
its minimum, which corresponds to a stable dynamical state of hydrodynamical
system. This result demonstrates the ability of our novel approach.Comment: 7 pages, published version URL
https://astro.bas.bg/AIJ/issues/n38/SDonkov.pd
Utilization-Based Scheduling of Flexible Mixed-Criticality Real-Time Tasks
Mixed-criticality models are an emerging paradigm for the design of real-time
systems because of their significantly improved resource efficiency. However,
formal mixed-criticality models have traditionally been characterized by two
impractical assumptions: once \textit{any} high-criticality task overruns,
\textit{all} low-criticality tasks are suspended and \textit{all other}
high-criticality tasks are assumed to exhibit high-criticality behaviors at the
same time. In this paper, we propose a more realistic mixed-criticality model,
called the flexible mixed-criticality (FMC) model, in which these two issues
are addressed in a combined manner. In this new model, only the overrun task
itself is assumed to exhibit high-criticality behavior, while other
high-criticality tasks remain in the same mode as before. The guaranteed
service levels of low-criticality tasks are gracefully degraded with the
overruns of high-criticality tasks. We derive a utilization-based technique to
analyze the schedulability of this new mixed-criticality model under EDF-VD
scheduling. During runtime, the proposed test condition serves an important
criterion for dynamic service level tuning, by means of which the maximum
available execution budget for low-criticality tasks can be directly determined
with minimal overhead while guaranteeing mixed-criticality schedulability.
Experiments demonstrate the effectiveness of the FMC scheme compared with
state-of-the-art techniques.Comment: This paper has been submitted to IEEE Transaction on Computers (TC)
on Sept-09th-201
The Knowledge in Automotive Field Representation with Modern Technologies
Modern technologies have changed the way of presenting
information in archives. This makes it possible to introduce new services,
which was unimaginable a few years ago. Digitalization, security and virtual
presentation of objects in the sphere of motoring by application of technologies,
based on knowledge about how to create digital resources is the theme of this
project.
The aim of AutoKnow project is to carry out a research and create a multi-
media digital archive AutoKnow and Experimental Virtual Motor Laboratory
(EVML) with Motor Library (ML) from digital multi-media patterns from a
selected group of objects in the sphere of automobile technology, presented by
NMU. This makes it possible to widely apply multi-media collections in
automobile engineering, teaching, research work in that sphere and serve the
interests of a large number of auto-amateurs as well in Bulgaria.
The research and development of АutoKnow is in the following mutually
related fields:
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Creation and annotation of collections of objects in the sphere of
automobiles;
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Creation, analysis and security of a digital archive AutoKnow;
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Design and creation of Digital Motor Library;
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Socially-oriented applications in education, scientific studies and
Experimental Virtual Motor Laboratory;
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Informational System for teaching and testing of knowledge in the
sphere of automobiles MindCheck
ALOHA: A Unified Platform-Aware Evaluation Method for CNNs Execution on Heterogeneous Systems at the Edge
CNN design and deployment on embedded edge-processing systems is an error-prone and effort-hungry process, that poses the need for accurate and effective automated assisting tools. In such tools, pre-evaluating the platform-aware CNN metrics such as latency, energy cost, and throughput is a key requirement for successfully reaching the implementation goals imposed by use-case constraints. Especially when more complex parallel and heterogeneous computing platforms are considered, currently utilized estimation methods are inaccurate or require a lot of characterization experiments and efforts. In this paper, we propose an alternative method, designed to be flexible, easy to use, and accurate at the same time. Considering a modular platform and execution model that adequately describes the details of the platform and the scheduling of different CNN operators on different platform processing elements, our method captures precisely operations and data transfers and their deployment on computing and communication resources, significantly improving the evaluation accuracy. We have tested our method on more than 2000 CNN layers, targeting an FPGA-based accelerator and a GPU platform as reference example architectures. Results have shown that our evaluation method increases the estimation precision by up to 5× for execution time, and by 2\times for energy, compared to other widely used analytical methods. Moreover, we assessed the impact of the improved platform-awareness on a set of neural architecture search experiments, targeting both hardware platforms, and enforcing 2 sets of latency constraints, performing 5 trials on each search space, for a total number of 20 experiments. The predictability is improved by 4\times , reaching, with respect to alternatives, selection results clearly more similar to those obtained with on-hardware measurements
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