The Impact of Precision Tuning on Embedded Systems Performance: A Case Study on Field-Oriented Control

Field Oriented Control (FOC) is an industry-standard strategy for controlling induction motors and other kinds of AC-based motors. This control scheme has a very high arithmetic intensity when implemented digitally - in particular it requires the use of trigonometric functions. This requirement contrasts with the necessity of increasing the control step frequency when required, and the minimization of power consumption in applications where conserving battery life is paramount such as drones. However, it also makes FOC well suited for optimization using precision tuning techniques. Therefore, we exploit the state-of-the-art FixM methodology to optimize a miniapp simulating a typical FOC application by applying precision tuning of trigonometric functions. The FixM approach itself was extended in order to implement additional algorithm choices to enable a trade-off between execution time and code size. With the application of FixM on the miniapp, we achieved a speedup up to 278%, at a cost of an error in the output less than 0.1%

JIST: just-in-time scheduling translation for parallel processors

The application fields of bytecode virtual machines and VLIW processors overlap in the area of embedded and mobile systems, where the two technologies offer different benefits, namely high code portability, low power consumption and reduced hardware cost. Dynamic compilation makes it possible to bridge the gap between the two technologies, but special attention must be paid to software instruction scheduling, a must for the VLIW architectures. We have implemented JIST, a Virtual Machine and JIT compiler for Java Bytecode targeted to a VLIW processor. We show the impact of various optimizations on the performance of code compiled with JIST through the experimental study on a set of benchmark programs. We report significant speedups, and increments in the number of instructions issued per cycle up to 50% with respect to the non-scheduling version of the JITcompiler. Further optimizations are discussed

Multi-objective co-exploration of source code transformations and design space architectures for low-power embedded systems

The exploration of the architectural design space in terms of energy and performance is of mainly importance for a broad range of embedded platforms based on the System-On-Chip approach. This paper proposes a methodology for the co-exploration of the design space composed of architec-tural parameters and source program transformations. A heuristic technique based on Pareto Simulated Annealing (PSA) has been used to efficiently span the multi-objective co-design space composed of the product of the parame-ters related to the selected program transformations and the configurable architecture. The analysis of the proposed framework has been carried out for a parameterized super-scalar architecture executing a selected set of benchmarks. The reported results show the effectiveness of the proposed co-exploration with respect to the independent exploration of the transformation and architectural spaces to efficiently derive approximate Pareto curves

Automated instantiation of side-channel attacks countermeasures for software cipher implementations

Side Channel Attacks (SCA) have proven to be a practical threat to the security of embedded systems, exploiting the information leakage coming from unintended channels concerning an implementation of a cryptographic primitive. Given the large variety of embedded platforms, and the ubiquity of the need for secure cryptographic implementations, a systematic and automated approach to deploy SCA countermeasures at design time is strongly needed. In this paper, we provide an overview of recent compiler-based techniques to protect software implementations against SCA, making them amenable to automated application in the development of secure-by-design systems

Landscape and energy production : possible co-existence?

This paper shows the energy production of some photovoltaic plants located in the province of Ragusa (Italy) and their impact on the landscape. The systems were realized and monitored by the authors since installation. The plants located in Ragusa, Marina di Ragusa, Santa Croce Camerina, Pozzallo, in Ragusa province, have been studied from the point of view of the yield and of their installation compared to the surrounding environment. The goal imposed by Italian regulations and design analysis of the authors, was to find solutions to find a balance between productivity and impact on the landscape.Bajada New Energy, Bitmac ltd., Econetique, Energy Investment, JMV Vibro Blocks, Solar Engineering.peer-reviewe

Encasing Block Ciphers to Foil Key Recovery Attempts via Side Channel

Providing efficient protection against energy consumption based side channel attacks (SCAs) for block ciphers is a relevant topic for the research community, as current overheads are in the 100× range. Unprofiled SCAs exploit information leakage from the outmost rounds of a cipher; we propose a solution encasing it between keyed transformations amenable to an efficient SCA protection. Our solution can be employed as a drop in replacement for an unprotected implementation, or be retrofit to an existing one, while retaining communication capabilities with legacy insecure endpoints. Experiments on a Cortex-M4 μC, show performance improvements in the range of 60×, compared with available solutions

TAFFO: The compiler-based precision tuner

We present taffo, a framework that automatically performs precision tuning to exploit the performance/accuracy trade-off. In order to avoid expensive dynamic analyses, taffo leverages programmer annotations which encapsulate domain knowledge about the conditions under which the software being optimized will run. As a result, taffo is easy to use and provides state-of-the-art optimization efficacy in a variety of hardware configurations and application domains. We provide guidelines for the effective exploitation of taffo by showing a typical example of usage on a simple application, achieving a speedup up to 60% at the price of an absolute error of 3.53×10−5. taffo is modular and based on the solid llvm technology, which allows extensibility to improved analysis techniques, and comprehensive support for the most common precision-reduced data types and programming languages. As a result, the taffo technology has been selected as the precision tuning tool of the European Training Network on Approximate Computing