Microarchitecture Research Articles

A Low-cost Fault Tolerance Method for ARM and RISC-V Microprocessor-based Systems using Temporal Redundancy and Approximate Computing through Simplified Iterations

Approximate Computing techniques have been successfully used to reduce the overhead associated with redundancy in fault-tolerant system designs. This paper presents a fault tolerance method to reduce the execution time overhead of the well-known Time Redundancy technique by means of an improvement proposed for the Approximate Computing software-based technique known as loop perforation. Time Redundancy is a software-based fault tolerance technique that involves executing replicas of a task at different times. We propose to approximate the tasks to be executed using a new approximate computing technique based on loop perforation, i.e., simplified iterations. The novelty of this method is the combined use of the fault tolerance technique, temporal redundancy, jointly with the new proposed Approximate Computing technique, simplified iterations. The proposal is validated through simulation-based fault injection campaigns on several test programs for the ARM and RISC-V microprocessor architectures. Experimental results verified not only the applicability of the proposal in different architectures, but also its effectiveness, showing a good trade-off between reliability, error and overhead. Results showed that using the proposed method, a normalized mean work to failure (MWTF) up to 5.28× was obtained with approximation errors lower than those obtained using the traditional loop perforation technique.

Addressing Student Fatigue in Computer Architecture Courses

Understanding the architecture of a processor can be uninteresting and deterring for computer science students, since low-level details of computer architecture are often perceived to lack real-world impact. These courses typically have a strong practical component where students learn the fundamentals of the computer architecture and the handling of input/output operations through the development of simple programs in a low-level assembly programming language. Since these practical sessions require a strong involvement, student attendance and withdrawal rates are poor, lowering academic results and introducing a negative feedback loop that preconditions students to dislike them. This article introduces a new methodology for the practical sessions of Computer Organization and Design courses. This methodology disavows the use of simulators and focuses on actual hardware to promote a feeling of proximity to the execution and outcome of the programs. The proposed setup uses Raspberry Pi devices to encourage students to work autonomously, due to their low cost, capability of running an OS, and rich ecosystem of simple hardware devices. The setup is completed with RISC OS, which combines a simple window-based graphical interface with a low-level management of the hardware without requiring software abstraction layers. The article presents the methodology and the UCDebug tool, developed to help students debug their codes in RISC OS. After the introduction of the new setup at the University of Cantabria, academic results and student satisfaction have improved. The setup has also allowed to sustain a similar organization of the courses throughout the COVID-19 pandemic.

FARKLI ETİK KURAMLARININ KURUMSAL ETİK TUTUM VE DAVRANIŞ KURALLARINA ETKİSİ: BİR KARŞILAŞTIRMALI SEMANTİK ANALİZ

The aim of this study was to investigate the influence of various theories of ethics on codes of conduct or codes of ethics of computing and data organizations. To quantify and evaluate the differences in influence, four Python libraries, namely difflib, gensim, nltk, and spaCy, and, in addition, a web-based proprietary semantic similarity tool, Compare Text, were used. The codes of seven computing and data organizations for Information Technology (IT) professionals and scholars were compared to the descriptions of five different schools of ethical thought through four different tools. The findings were tabularized, summarized in radar charts, and their implications were discussed: It was found that there are some differences of influence on the codes by different theories. However, the percentages of similarities calculated by each tool were observed to differ, on some occasions, considerably. Finally, contributions and limitations of the current work and recommendations for further studies were presented.

Recursive-Parallel Algorithm for Solving the Graph-Subgraph Isomorphism Problem

The paper proposes a parallel algorithm for solving the Graph-Subgraph Isomorphism Problem and makes an experimental study of its efficiency. The problem is one of the most famous NP-complete problems. Its solution may be required when solving many practical problems associated with the study of complex structures. We solve the problem in a formulation that requires finding all existing isomorphic substitutions or proving their absence. In view of the high complexity of the problem, it is natural to want to speed up its solution by parallelizing the algorithm.We used the RPM ParLib library, developed by the author, as the main tool to program the algorithm. This library allows us to develop effective applications for parallel computing on a local network under the control of the runtime environment .NET Framework. Thanks to this library, applications have the ability to generate parallel branches of computation directly during program execution and dynamically redistribute work between computing modules. Any language with support of the .NET Framework can be used as a programming language in conjunction with this library. For the numerical experiment, an open database from the Internet was used, which was specially developed to study algorithms for searching for isomorphic substitutions. Also, the author has developed a special application in C# for generating additional sets of initial data with specified characteristics. The aim of the experiment was to study the speedup achieved due to the recursively parallel organization of computations. The paper provides a detailed description of the proposed algorithm, as well as the results obtained during the experiment.

Evaluation of enterprise financial investment environment based on block‐chain and cloud computing

AbstractImproving and strengthening the various factors of the financial investment system to improve the entire investment system has become an important part of modern economic development. This research is based on block‐chain and cloud computing on the evaluation of corporate financial investment environment. It aims to fully apply the advantages of block‐chain and computing technology to conduct a thorough analysis of corporate financial investment environment and increase the stability of corporate financial investment decisions. Provide economic benefits to a certain extent. The article mainly analyzes the status quo, influencing factors, and evaluation principles of the financial investment environment, and combines the advantages of cloud computing and block‐chain in data acquisition and processing applications to conduct experiments; this research constructs a structural correlation model between the enterprise and the external environment, and investment business data process and cloud computing and financial investment information organization structure model, which can visually present specific investment operation details, and so on; formulate comprehensive evaluation indicators for regional investment, and focus on the role of the institutional environment based on the analysis of the role of regional factors on the regional development of the enterprise. The research results show that cloud computing technology and block‐chain technology have greatly improved the construction of financial investment data whether it is intertemporal, predictive or follow‐up. From the data inspection results, the maximum value of this performance has been expanded from the original 5.98 to 9.27; from the perspective of computational performance, it has been increased from 5.98 to 9.27.

Pegasus: Performance Engineering for Software Applications Targeting HPC Systems

Developing and optimizing software applications for high performance and energy efficiency is a very challenging task, even when considering a single target machine. For instance, optimizing for multicore-based computing systems requires in-depth knowledge about programming languages, application programming interfaces, compilers, performance tuning tools, and computer architecture and organization. Many of the tasks of performance engineering methodologies require manual efforts and the use of different tools not always part of an integrated toolchain. This paper presents Pegasus, a performance engineering approach supported by a framework that consists of a source-to-source compiler, controlled and guided by strategies programmed in a Domain-Specific Language, and an autotuner. Pegasus is a holistic and versatile approach spanning various decision layers composing the software stack, and exploiting the system capabilities and workloads effectively through the use of runtime autotuning. The Pegasus approach helps developers by automating tasks regarding the efficient implementation of software applications in multicore computing systems. These tasks focus on application analysis, profiling, code transformations, and the integration of runtime autotuning. Pegasus allows developers to program their strategies or to automatically apply existing strategies to software applications in order to ensure the compliance of non-functional requirements, such as performance and energy efficiency. We show how to apply Pegasus and demonstrate its applicability and effectiveness in a complex case study, which includes tasks from a smart navigation system.

An optimization approach to the development of parallel algorithms for digital signal processing operations

The paper studies the optimization possibilities of an approach which made it possible to develop a formal tool, i.e. a model of computation organization for digital signal processing (DSP) operations and operations structurally similar to them. The resulting formal tool describes the inter-nal parameterized structure of operations and generates adaptive algorithms that can adjust to dif-ferent conditions of parallel computation. The developed approach to the construction of such algo-rithms endows them with extended functionality, which ensures the implementation of the follow-ing capabilities: changes in the parameters of algorithm structures; synthesis of their variety; opti-mization of variants of computation organization. Due to the variety of this functionality, several directions are identified for implementing this optimization. A general description of the optimiza-tion approach to the reasonable choice of the best variant of computation organization under the given conditions of their implementation is given. We consider a scheme of actions aimed at com-putation optimization and enabling you to develop various classes of parameterized parallel algo-rithms within the framework of the approach proposed.

Heuristic algorithms in evolutionary computation and modular organization of biological macromolecules: Applications to in vitro evolution.

Evolutionary computing (EC) is an area of computer sciences and applied mathematics covering heuristic optimization algorithms inspired by evolution in Nature. EC extensively study all the variety of methods which were originally based on the principles of selectionism. As a result, many new algorithms and approaches, significantly more efficient than classical selectionist schemes, were found. This is especially true for some families of special problems. There are strong arguments to believe that EC approaches are quite suitable for modeling and numerical analysis of those methods of synthetic biology and biotechnology that are known as in vitro evolution. Therefore, it is natural to expect that the new algorithms and approaches developed in EC can be effectively applied in experiments on the directed evolution of biological macromolecules. According to the John Holland's Schema theorem, the effective evolutionary search in genetic algorithms (GA) is provided by identifying short schemata of high fitness which in the further search recombine into the larger building blocks (BBs) with higher and higher fitness. The multimodularity of functional biological macromolecules and the preservation of already found modules in the evolutionary search have a clear analogy with the BBs in EC. It seems reasonable to try to transfer and introduce the methods of EC, preserving BBs and essentially accelerating the search, into experiments on in vitro evolution. We extend the key instrument of the Holland's theory, the Royal Roads fitness function, to problems of the in vitro evolution (Biological Royal Staircase, BioRS, functions). The specific version of BioRS developed in this publication arises from the realities of experimental evolutionary search for (DNA-) RNA-devices (aptazymes). Our numerical tests showed that for problems with the BioRS functions, simple heuristic algorithms, which turned out to be very effective for preserving BBs in GA, can be very effective in in vitro evolution approaches. We are convinced that such algorithms can be implemented in modern methods of in vitro evolution to achieve significant savings in time and resources and a significant increase in the efficiency of evolutionary search.

Meta-analysis of human prediction error for incentives, perception, cognition, and action.

Prediction errors (PEs) are a keystone for computational neuroscience. Their association with midbrain neural firing has been confirmed across species and has inspired the construction of artificial intelligence that can outperform humans. However, there is still much to learn. Here, we leverage the wealth of human PE data acquired in the functional neuroimaging setting in service of a deeper understanding, using an MKDA (multi-level kernel-based density) meta-analysis. Studies were identified with Google Scholar, and we included studies with healthy adult participants that reported activation coordinates corresponding to PEs published between 1999-2018. Across 264 PE studies that have focused on reward, punishment, action, cognition, and perception, consistent with domain-general theoretical models of prediction error we found midbrain PE signals during cognitive and reward learning tasks, and an insula PE signal for perceptual, social, cognitive, and reward prediction errors. There was evidence for domain-specific error signals--in the visual hierarchy during visual perception, and the dorsomedial prefrontal cortex during social inference. We assessed bias following prior neuroimaging meta-analyses and used family-wise error correction for multiple comparisons. This organization of computation by region will be invaluable in building and testing mechanistic models of cognitive function and dysfunction in machines, humans, and other animals. Limitations include small sample sizes and ROI masking in some included studies, which we addressed by weighting each study by sample size, and directly comparing whole brain vs. ROI-based results.

On functional programming in the organization of parallel computing

On functional programming in the organization of parallel computing

A Systematic Review on Importance of Employee Turnover with Special Reference to Turnover Strategies

This studies targets to apprehend the reasons of worker turnover and retention techniques in a business enterprise. Key studies findings suggest that personnel have numerous motives to go away their workplaces, including activity strain, activity pride, activity security, motivation, wages, and rewards. Furthermore, worker turnover has a large effect on a business enterprise because of the prices related to worker turnover and may negatively affect the productiveness, sustainability, competitiveness, and profitability of a business enterprise. However, the business enterprise need to apprehend the wishes of its personnel, with the intention to assist agencies, undertake positive techniques to enhance worker overall performance and decrease turnover. Thus, imposing techniques will growth activity pride, motivation and the productiveness of people and agencies that may lessen employment issues, absenteeism, and worker turnover. In a HR setting, turnover or work turnover is the rate at which a business gains and loses representatives. Basic method for portraying it are "the way lengthy workers will generally remain" or "the pace of traffic through the rotating entryway." Turnover is estimated for individual organizations and for their industry all in all. Assuming a business is said to have a high turnover comparative with its rivals, it implies that representatives of that organization have a more limited typical residency than those of different organizations in a similar industry. High turnover might be hurtful to an organization's efficiency in the event that gifted labourers are much of the time leaving and the specialist populace contains a high level of fledgling labourers. Unreasonable turnover can be an expensive issue, one with a significant effect on efficiency. One firm had a turnover pace of over 120% each year. It cost the organization $1.5 million a year in lost efficiency, expanded preparing time, expanded worker determination time, lost work productivity, and other roundabout expenses. Yet, cost isn't the main explanation turnover is significant. Extended preparing times, hindered plans, extra time, botches, and not having educated representatives set up are a portion of the disappointments related with over the top turnover. Turnover rates normal around 16% each year for all organizations, yet 21% each year for IT companies.54 Computer organizations normal higher turnover on the grounds that their representatives have numerous potential chances to change occupations in a "hot" industry. Many investigations show that organizations with low turnover rates are very representative situated. Representative situated associations request info and contribution from all workers and keep a valid "open-entryway" strategy. Workers are given open doors for progression and are not obsessively hovered over. Workers accept they have a voice and are perceived for their commitment.

A Study on Hazards of Computer Viruses

Computer use is becoming part of our lives every other day however there have been considerable threats of computer viruses in the recent past. Viruses have had adverse effects on data and programs ranging from formatting hard disks, damaging information infrastructure, suddenly restarting machines, deleting or modifying data and in some cases mild effects such as slowing down machines or producing irritating sounds. Viruses have been a major cause for worry especially with the advances in data processing, storage and movement of information technologically. Many computer users and organizations especially the computer intensive organizations have had to invest heavily in dealing with viruses particularly those organizations running the windows platform. These computer viruses have been defined by their characteristics of entry and multiplication without the user’s notice as well as diverting the normal functioning of the computer. This paper seeks to define a virus and explain its related terms such as malicious software, worms, and Trojan horses. It explains vulnerabilities of operating systems in relation to viruses, it makes an observation on strengths of Linux versus Windows, outline the present state of affairs, apart from using anti-virus software, there are other procedures which can help protect against viruses which are also mentioned, the future of computer viruses and the conclusion that the Internet is serving its purpose of interconnecting computer and hence promoting distribution of viruses then makes some recommendations on viruses.

The POWER Processor Family: A Historical Perspective From the Viewpoint of Presilicon Modeling

Presilicon modeling is a crucial and integral part of processor microarchitecture definition and optimization. In this article, I attempt to provide a retrospective view of IBM's POWER and PowerPC microprocessors, through the lens of someone who has been associated with such modeling in support of microarchitecture definition and optimization from the earliest days of this particular family of processors. The focus in the early/mid-1980s was on cycle-accurate performance modeling; much later, beginning in 1999 or so, the looming power wall triggered a new era of power-performance modeling at the microarchitecture level. Subsequently, temperature-aware and reliability-aware modeling were added dimensions that CMOS technology evolution drove us into. The problem of model validation is an unavoidable aspect of presilicon modeling. Without that mindset, the microarchitecture definition team can make serious mistakes, which results in unpleasant postsilicon surprises. I provide pointers to early approaches in addressing this issue. The article attempts to mention the contributions of many talented researchers and engineers that have, over the years, contributed immensely to the evolution of the POWER/PowerPC microprocessors from earliest research concepts through the recently announced POWER10—using model-based analysis to ensure competitive performance growth.

Curriculum Reform of Computer Organization and Architecture under the Epidemic Situation

Computer organization and architectureis the core hardware courseof computer majors. Its abstract and obscure characteristics make it difficult for teachers to teach and students to learn. Under the epidemic situation, traditional teaching methods are facing new challenges, theoretical teaching lacks innovative thinking, experimental course lacks design content, and lacks of leading courses. The combination of online and offline is proposed, the advanced concepts at home and abroad, the FPGA technology and assembly programmingdesign and other measures are introduced to improve the quality of training hardware talents.

Evaluating reliability through soft error triggered exceptions at ARM Cortex-A9 microprocessor

ARM Cortex-A9 is a high-end microprocessor present in multiple programmable System-on-Chip that is used in many application fields, including those with high reliability requirements. This work aims to understand better the behaviour of a high-end microprocessor in a harsh environment through the analysis, evaluation, and classification of exceptions. Exceptions triggered by radiation effects may end up in an unresponsive state of the microprocessor which is undesirable in high reliability scenarios. Experimental results of both fault injection and irradiation presented in this work provide an extensive analysis of the exceptions and their relationship with the executed code, the usage of operating systems and microprocessor architecture.

THE RUNTIME ANALYSIS OF COMPUTATION OF MODULAR EXPONENTIATION

Context. Providing the problem of fast calculation of the modular exponentiation requires the development of effective algorithmic methods using the latest information technologies. Fast computations of the modular exponentiation are extremely necessary for efficient computations in theoretical-numerical transforms, for provide high crypto capability of information data and in many other applications.
 Objective – the runtime analysis of software functions for computation of modular exponentiation of the developed programs based on parallel organization of computation with using multithreading.
 Method. Modular exponentiation is implemented using a 2k-ary sliding window algorithm, where k is chosen according to the size of the exponent. Parallelization of computation consists in using the calculation of the remainders of numbers raised to the power of 2i modulo, and their further parallel multiplications modulo.
 Results. Comparison of the runtimes of three variants of functions for computing the modular exponentiation is performed. In the algorithm of parallel organization of computation with using multithreading provide faster computation of modular exponentiation for exponent values larger than 1K binary digits compared to the function of modular exponentiation of the MPIR library. The MPIR library with an integer data type with the number of binary digits from 256 to 2048 bits is used to develop an algorithm for computing the modular exponentiation with using multithreading.
 Conclusions. In the work has been considered and analysed the developed software implementation of the computation of modular exponentiation on universal computer systems. One of the ways to implement the speedup of computing modular exponentiation is developing algorithms that can use multithreading technology on multi-cores microprocessors. The multithreading software implementation of modular exponentiation with increasing from 1024 the number of binary digit of exponent shows an improvement of computation time with comparison with the function of modular exponentiation of the MPIR library.

КОМП’ЮТЕРНО-ОРІЄНТОВАНІ ЕЛЕМЕНТИ НАВЧАННЯ МАТЕМАТИЧНИХ ДИСЦИПЛІН МАЙБУТНІХ УЧИТЕЛІВ МАТЕМАТИКИ

The article is devoted to the issues of constructing effective computer-oriented components of the methodological system of teaching the disciplines «Linear Algebra» and «Probability Theory with Elements of Mathematical Statistics» provided for in the educational and professional program «Secondary Education (Mathematics)» of the first level of higher education in the specialty 014 Secondary Education (Mathematics). The article analyzes the methodological aspects of the effective organization of computations when finding the angle between a given vector and a nonzero subspace of Euclidean space, as well as using the least squares method for processing experimental data. The theoretical and practical information known to students-mathematicians from the corresponding sections of these academic disciplines is briefly presented. Analyzed educational, methodological and scientific literature used in teaching linear algebra and probability theory with elements of mathematical statistics; the expediency of using computer-oriented elements of teaching mathematical disciplines of future mathematics teachers has been substantiated. The authors proposed the use of computer-oriented learning elements in the processing of the content of disciplines and the development of test tasks of different levels of complexity in linear algebra and probability theory with elements of mathematical statistics in order to objectively assess the level of students' knowledge and timely correct individual educational trajectories. The article provides examples of the application of computer-oriented elements of teaching linear algebra and probability theory with elements of mathematical statistics, and also analyzes the methodological features of the organization of calculations in the software mathematical environment Mathcad. The methodological and practical materials presented in the article can be useful for students to organize and activate independent scientific and pedagogical activities, teachers of secondary educational institutions, heads of optional and circle work of students, teachers of linear algebra and probability theory courses with elements of mathematical statistics of pedagogical higher educational institutions. Key words: methods of teaching mathematics, computer-oriented elements of teaching mathematics, linear algebra, probability theory, mathematical statistics, Euclidean space, non-zero subspace of Euclidean space, least squares method.

DECISION TREE DALAM MENGKLASIFIKASI MATA KULIAH TERHADAP PEMAHAMAN SISTEM PEMASARAN

With the proliferation of applications that support the buying and selling process or better known as e-commerce, and currently online buying and selling is a trend among students, and also a source of income that can be done in spare time, therefore to be able to increase the results of using e-commerce. -commerce required an understanding of the marketing system. In this study, research was conducted on what subjects were taught to students at the Fakultas Teknik dan Ilmu Komputer, Universitas Muhammadiyah Pekajangan Pekalongan which would help in understanding the marketing system. The C4.5 classification algorithm is used to build a decision tree that will make it easier to see courses that can be used to understand the marketing system. After the analysis, the subjects of entrepreneurship, management information systems, design analysis and information systems, data communication and computer networks, computer organization and algorithms and structured programming can be used to gain an understanding of marketing systems.

Comparative study on cryptocurrency transaction and banking transaction

Cryptocurrency is an advanced digital currency that is gotten by cryptography, numerous digital currencies are decentralized organizations dependent on blockchain innovation an appropriated record authorized by a different organization of computers. And Many present-day technologies are driving the transformative impact in the global financial system, in that impact cryptocurrency stands on first position in the list. Cryptocurrency offer several potential benefits, including better speed and efficiency in processing payments and transfers notably across borders and ultimately boosting financial inclusion. The intension of this paper is to summaries the difference between the normal or traditional method of currency transaction and crypto currency transaction. And why all are providing more interest towards crypto methods nowadays and what different they feel while choosing a crypto method over a normal or traditional currency methods. And how crypto currency is dragging current world attention towards its pocket and why many are developing interest towards following the crypto trend.

Implementasi System Usability Scale untuk Pengujian Usabilitas Chronum Calculator

Chronum Calculator is an alternative learning aid developed to support learning about number conversion. Chronum Calculator is a multimedia learning application that can be used to calculate and describe how to calculate the conversion between types of numbers and the conversion of numbers into color display. In previous research, this application was developed on the Android platform and is planned to be used as a learning aid in computer network and computer organization courses. Therefore, reusability test of this application is needed. Testing and measuring the quality of application reusability is done using the System Usability Scale (SUS) method. The reusability testing questionnaire was given to 31 samples of lecturers and students. The measurement result shows the number 76.38 and is considered acceptable. Where this means that the Chronum Calculator can be well received by users and meets application reusability standards. The results of this research can be used as a basis for further research on the analysis of the effect of usability on user satisfaction chronum calculators in online lectures. Keywords : Android, SUS, Usability, Respondents, Measuring