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This paper encompasses the corrections of the paper "File System Performance Comparison in Full Hardware Virtualization with ESXi, KVM, Hyper-V, and Xen Hypervisors." The corrections have been made in section II. RELATED WORK, OBJECTIVE AND MOTIVATION, and the References section. The paper "File System Performance Comparison in Full Hardware Virtualization with ESXi, KVM, Hyper-V, and Xen Hypervisors," authored by B. Djordjevic, V. Timcenko, N. Kraljevic, N. Macek, represents a significant extension of the IEEE conference paper "File system performance comparison in full hardware virtualization with ESXi and Xen hypervisors," authored by B. Dordevic, V. Timcenko, N. Kraljevic, and N. Davidovic. This paper explains the corrections of the "File System Performance Comparison in Full Hardware Virtualization with ESXi, KVM, Hyper-V, and Xen Hypervisors" paper and compares the mentioned papers in detail. [ABSTRACT FROM AUTHOR]

This paper examines computer virtualization as a solution to issues encountered in maintaining HMI and SCADA systems based on commercial off-the-shelf computing hardware. Following a brief primer, this paper outlines issues arising from the rapid advancement of personal and server computing hardware, including automation software conflicts with new operating systems, device driver availability for old operating systems, and migrating backup images to new hardware. Opportunities for improvement are identified in backup and recovery, operator access to computing resources, and prototyping HMI and program changes. The concept of a virtual machine is introduced, and common architectures are examined, followed by the description of an example virtualized control room. Finally, this paper examines the experiences of a multisite cement producer in implementing virtualization in two of their plants. This examination explores the reasoning, advantages, disadvantages, and limitations encountered in moving existing systems to a virtualized platform. [ABSTRACT FROM AUTHOR]

The MPRA (Multi Pipeline Register Architecture) was modified and converted into n-task MPRA (nMPRA) by replicating the pipeline registers. While the original MPRA provided hardware scheduling, the interrupts and the events caused too long delays. The author proposes the original solutions for the interrupts and the events treatment, which represent the author's contribution to improving nMPRA; after the theoretical presentations of these solutions in the author's previous articles, this paper presents the implementations of the schemes, the results of the tests and the improved schemes. The MPRA, MPRA4 and MPRA8 implementations on FPGA (Field Programmable Gate Array) were used to evaluate performances. A detailed analysis, partially presented in this paper, shows other advantages: no extra software is required, the hardware implementation is simple, the interrupts and events are similarly handled and the tasks synchronizations and communications are completely based on hardware; MPRA has a low power consumption, even multiplied by eight times, it is reasonably necessary memory and logic resource consumption multiplied by about four times at MPRA4 (compared to MPRA) and by about eight times at MPRA8. [ABSTRACT FROM AUTHOR]

Wang et al. proposed a method for obtaining elliptic curves with embedding degree 1 for securing critical infrastructures, and presented several elliptic curves generated by their method with torsion points of 160 bits and 189 bits orders. They also presented some experimental results and claimed that their implementation of an elliptic curve generated with their method is faster than an implementation for embedded devices presented by Bertoni et al. In this paper, we point out that the security and efficiency claims given by Wang et al. are flawed. Specifically, we show that it is possible to solve finite field discrete logarithm problems defined over their elliptic curves in practice. On the elliptic curves with torsion points of 160 bits orders generated by Wang et al., their instances of finite field discrete logarithm problems are solved in around 4 hours by using a standard desktop PC. On the torsion points of 189 bits orders, their instances are solved in around 10 days by using two standard desktop PCs. The hardness of the finite field discrete logarithm problems is one of the most important bases of security; therefore, their elliptic curves should not be used for cryptographic purposes. [ABSTRACT FROM AUTHOR]

This paper focus is the mathematical modeling of the file system performance in virtual environment when using type-1 hypervisors. The modeling provides a set of hypotheses related to the expected behavior. The presented model is validated based on the analysis of a collection of the results obtained for a specific case study. Our case study includes the file system performance comparison, in full hardware virtualization, when examining four dominant type-1 hypervisors: ESXi, KVM, Hyper-V, and Xen. We chose Filebench as a benchmark tool, which guarantees comprehensive and versatile testing of file system performance, whereas for all tested hypervisors we have provided an equivalent environment and testing conditions. For all the examined hypervisors, we have tested the cases with one, two, and three virtual machines that are running simultaneously, whereas CentOS 6.3 Linux is used as the guest operating system. We have further validated the mathematical model and defined hypotheses by the means of the case study benchmark results. [ABSTRACT FROM AUTHOR]

Mobile platforms are prevalently used in the age of social media. They serve a two-sided market to connect users and app developers. In this system, members simultaneously sell products, publish advertisements (ads), and advertise. This paper aims to explore advertising strategies for the mobile platform incorporating their roles as sellers, ad publishers, and advertisers. Specifically, we develop a game-theoretical model which captures the relationship among the works of the platform owner and app developers in a dynamic setting. Our analysis shows that when the platform displays apps’ ads, the owner may be better off to participate in apps’ advertising under certain conditions, rather than always charging them aggressively as suggested by convention wisdom. Surprisingly, although the negative impacts evoked by multiple apps’ entry deserve much attention, it is unnecessary for app developers to take into account when making advertising decisions. We further find that the coordinating bilateral participation in advertising is a new mechanism to improve the profitability. Unlike the result proposed in the previous literature, the mechanism here will cause free-riding among app developers when they participate in the platform’s advertising. Furthermore, when accompanied with the revenue sharing policy, the relatively low participation rates could absolutely eliminate the system inefficiency. [ABSTRACT FROM AUTHOR]

Task context switching, unitary management of events, synchronization and communication mechanisms are significant problems for each real-time operating system. For real-time systems, another overhead factor is the processor's time to execute the routine of treating external asynchronous interrupts. The main objective of this paper is to describe, implement, and validate the preemptive scheduler module as part of the hardware accelerated real-time operating system, using the RISC-V instruction set and Verilog HDL. The new architecture contains the hardware structure used for static and dynamic scheduling of the tasks, real-time management of the events, and also defines a method used to attach interrupts to tasks. In order to accomplish this objective, it was necessary to structure CPU modules so as to ensure easy adaptation to other implementations (MIPS coprocessor, ARM or RISC-V). [ABSTRACT FROM AUTHOR]

This paper describes the concept and analysis of virtualization technology and possible virtualization scenarios, which can be used to create a new generation of Intelligent Electronic Devices (IEDs). The concept overview was based on solutions used in conventional IT systems. A general conception of virtualization is presented. A solution based on KVM virtualization is described. Synchronizing the time of virtual machines, as well as creating and testing virtual machines under Linux operating systems are described. Time delays of communication when sending SV messages between the IEDs using SV packages are compared. Communication and operation of virtual protections with physical IEDs devices were verified. [ABSTRACT FROM AUTHOR]

Modern Linux operating systems are being used in a wide range of fields, from small IoT embedded devices to supercomputers. However, most machines use the default Linux scheduler parameters implemented for general-purpose environments. The problem is that the Linux scheduler cannot utilize the features of the various hardware and software environments, and it is therefore, difficult to achieve optimal performance in the machines. In this paper, we propose STUN, an automatic scheduler optimization framework. STUN modifies the five scheduling policies of the Linux kernel and 10 parameters automatically to optimize for each workload environment. STUN decreases the training time and enhances the efficiency through a filtering mechanism and training reward algorithms. Using STUN, users can optimize the performance of their machines at the OS scheduler level without manual control of the scheduler. STUN showed an execution time and improved FPS of 18.3% and 22.4% on a face detection workload, respectively. In addition, STUN showed 26.97%, 54.42%, and 256.13% performance improvements for microbenchmarks with 4, 44, and 120 cores for each. [ABSTRACT FROM AUTHOR]

In the field of development, Internet of things (IoT) plays a crucial role in providing solution to various situations. A lot of research has been conducted recently to model IoT based operating systems as standard UNIX, Windows and current real time operating systems are unable to meet the demand of heterogeneous IoT applications. In this paper we will focus on major OS features such as architecture, programming model, portability, memory management, real-time environment, scheduling algorithm, hardware support, networking and energy efficiency. We will be focusing on the following six operating systems which are as follows: Contiki, Tiny OS, RIOT, Zypher, Mbed and Brillo. [ABSTRACT FROM AUTHOR]

File I/O buffer caching plays an important role to narrow the wide speed gap between main memory and secondary storage. However, data loss or inconsistency may occur if the system crashes before updated data in the buffer cache is flushed to storage. Thus, most operating systems adopt a daemon that periodically flushes dirty data to secondary storage. This periodic flush degrades the caching efficiency seriously because most write requests lead to direct storage accesses. We show that periodic flush accounts for 30-70 percent of the total write traffic to storage. To remove this inefficiency, this paper presents a new buffer cache architecture that adopts a small amount of non-volatile memory to maintain modified data. This novel buffer cache architecture removes almost all storage accesses due to periodic flush operations without any loss of reliability. It also improves the buffer cache performance through space-efficient management techniques, such as delta-write and fragment-grouping. Our experimental results show that the proposed buffer cache reduces the storage write traffic by 44.3 percent and also improves the throughput by 23.6 percent on average. [ABSTRACT FROM PUBLISHER]

The purpose of this paper is to study the conditional inactivity time of failed components of a coherent system consisting of n identical components with statistically independent lifetimes. Different aging and stochastic properties of this conditional random variable are obtained. Some mixture representations for the conditional inactivity time of the components are also derived. We give sufficient conditions based on the signature and the common distribution of component lifetimes to obtain stochastic ordering results for coherent systems. Some stochastic orders on the dynamic signature of coherent systems are also provided. [ABSTRACT FROM PUBLISHER]

This paper investigates the performance of synchronization algorithms on ccNUMA multiprocessors, from the perspectives of the architecture and the operating system. In contrast with previous related studies that emphasized the relative performance of synchronization algorithms, this paper takes a new approach by analyzing the sources of synchronization latency on ccNUMA architectures and how can this latency be reduced by leveraging hardware and software schemes in both dedicated and multiprogrammed execution environments. From the architectural perspective, the paper identifies the implications of directory-based cache coherence on the latency and scalability of synchronization instructions and examines if and how can simple hardware that accelerates these instructions be leveraged to reduce synchronization latency. From the operating system's perspective, the paper evaluates in a unified framework, user-level, kernel-level and hybrid algorithms for implementing scalable synchronization in multiprogrammed execution environments. Along with visiting the aforementioned issues, the paper contributes a new methodology for implementing fast synchronization algorithms on ccNUMA multiprocessors. The relevant experiments are conducted on the SGI Origin2000, a popular commercial ccNUMA multiprocessor. [ABSTRACT FROM AUTHOR]

This paper presents a novel technique, called Zombie Chasing, for efficient flash management in solid state drives (SSDs). Due to the unique characteristics of NAND flash memory, SSDs need to accurately understand the liveness of the data stored in themselves. Recently, the TRIM command has been introduced to notify SSDs of dead data caused by file deletions, which otherwise could not be tracked by SSDs. This paper goes one step further and proposes a new liveness state, called the zombie state, to denote live data that will be dead shortly due to the corresponding dirty data in the buffer cache. We also devise new zombie-aware garbage collection algorithms which utilize the information about such zombie data inside SSDs. To evaluate Zombie Chasing, we implement zombie-aware garbage collection algorithms in the prototype SSD and modify the Linux kernel and the Oracle DBMS to deliver the information on the zombie data to the prototype SSD. Through comprehensive evaluations using our in-house micro-benchmark and the TPC-C benchmark, we observe that Zombie Chasing improves SSD performance effectively by reducing garbage collection overhead. Especially, our evaluation with the TPC-C benchmark on the Oracle DBMS shows that Zombie Chasing enhances the Transactions Per Second (TPS) value by up to 22% with negligible overhead. [ABSTRACT FROM AUTHOR]

To improve mobile experience of users, recent mobile devices have adopted powerful processing units (CPUs and GPUs). Unfortunately, the processing units often consume a considerable amount of energy, which in turn shortens battery life of mobile devices. For energy reduction of the processing units, mobile devices adopt energy management techniques based on software, especially OS (Operating Systems), as well as hardware. In this survey paper, we summarize recent OS-level energy management techniques for mobile processing units. We categorize the energy management techniques into three parts, according to main operations of the summarized techniques: 1) techniques adjusting power states of processing units, 2) techniques exploiting other computing resources, and 3) techniques considering interactions between displays and processing units. We believe this comprehensive survey paper will be a useful guideline for understanding recent OS-level energy management techniques and developing more advanced OS-level techniques for energy-efficient mobile processing units. [ABSTRACT FROM AUTHOR]

This paper describes the concept and analysis of virtualization technology and possible virtualization scenarios, which can be used to create a new generation of intelligent electronic devices (IEDs). The overview of the concept was based on solutions used in conventional IT systems. A fully operational working lab environment, in which simulated IED models were implemented, has been successfully tested. Problems associated with environment launch are described. An analysis of the influence of virtual device time synchronization and resynchronization on their correct operations is performed. Time delays of communication when sending GOOSE messages between the IEDs using GOOSE packages are verified. [ABSTRACT FROM PUBLISHER]

Low latency is one of the most important requirements for smart devices. Even though they have a small amount of memory, end users often want to run multiple applications concurrently without delays. Memory fragmentation is a critical obstacle to this aspect. To recover from it, the operating system uses compaction to create contiguous space from scattered free pages. Memory compaction tends to secure as many contiguous memory pages as it can, which may affect the user experience adversely at application launches. In this paper, a new page compaction method is proposed to improve the user experience. This method employs an efficient mechanism to find candidate pages to move. It also uses a bitmap to represent the status of the physical pages and find compactable pages effectively. The experiment performed on the proposed method demonstrates that the interruptions for compaction occur more frequently, but with a significantly lower workload than conventional compaction. According to the experiment, the success rate after compaction increased by about 22%, and the elapsed time to scan free pages decreased dramatically compared to conventional compaction. Moreover, the proposed method reduced the worst-case time for a new process creation by about 67%. [ABSTRACT FROM AUTHOR]

The allocation of the resources to be shared in the context of a distributed processing system needs to be coordinated through the mutual exclusion mechanism, which will decide the order in which the shared resources will be allocated to those processes that require them. This paper proposes an aggregation operator, which can be used by a module that manages the shared resources, whose function is to assign the resources to the processes according to their requirements (shared resources) and the status of the distributed nodes in which the processes operate (computational load), by using 2-tuple associated to linguistic labels. [ABSTRACT FROM AUTHOR]

This paper describes the developed technology for using the Raspberry Pi microcomputer to teach practical skills on computer networks and operating systems. The paper presents a largely implemented project on an initiative basis, preceding the work on commercialization of the described results. In the present work a full detailed content of the steps for implementation and subsequent commercialization of the solutions presented in the project is given. There was assembled a prototype of the hardware-software device. There were developed individual training kits for distribution to students in the classroom. To study the disciplines "Computer Networks" and "Operating Systems", a methodological manual is being prepared for studying these disciplines using these training kits; the guidelines for operation of devices and components were developed. The work also prepared boot files with the predefined working environment for each discipline. These files include the needed operating systems, the needed pre-installed software, a customized user interface, the needed literature, a training manual, and methodological recommendations. In terms of commercialization, the calculations were carried out on the costs of organizing a computer class based on the Raspberry Pi: implementation of the developed technology; the effectiveness of its implementation was evaluated. A commercial plan was drawn up and calculations were made on the current date with the reference mainly to Kazakhstan; the trial design and layout of the packaging case, information stickers and cover (as well as layout) of the training manual were completed; industrial designs were developed in order to prepare the project for commercialization. The results are practically significant, when they were received, widespread methodology and development tools were used, they can be universally used, including in the field of education without any restrictions. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present some preliminary results and non-extensive statistical properties of selected operating system counters related to hard drive behaviour. A number of experiments have been carried out in order to generate the workload and analyse the behaviour of computers during man-machine interaction. All analysed computers were personal ones, worked under Windows operating systems. The research was conducted to demonstrate how the concept of non-extensive statistical mechanics can be helpful in the description of computer systems behaviour, especially in the context of statistical properties with scaling phenomena, long-term dependencies and statistical self-similarity. The studies have been made on the basis of perfmon tool that allows the user to trace operating systems counters during processing. [ABSTRACT FROM AUTHOR]

Software Defined Networking (SDN) is an emerging promising paradigm for network management because of its centralized network intelligence. However, the centralized control architecture of the software-defined networks (SDNs) brings novel challenges of reliability, scalability, fault tolerance and interoperability. In this paper, we proposed a novel clustered distributed controller architecture in the real setting of SDNs. The distributed cluster implementation comprises of multiple popular SDN controllers. The proposed mechanism is evaluated using a real world network topology running on top of an emulated SDN environment. The result shows that the proposed distributed controller clustering mechanism is able to significantly reduce the average latency from 8.1% to 1.6%, the packet loss from 5.22% to 4.15%, compared to distributed controller without clustering running on HP Virtual Application Network (VAN) SDN and Open Network Operating System (ONOS) controllers respectively. Moreover, proposed method also shows reasonable CPU utilization results. Furthermore, the proposed mechanism makes possible to handle unexpected load fluctuations while maintaining a continuous network operation, even when there is a controller failure. The paper is a potential contribution stepping towards addressing the issues of reliability, scalability, fault tolerance, and inter-operability. [ABSTRACT FROM AUTHOR]

Software rejuvenation is a proactive software control technique that is used to improve a computing system performance when it suffers from software aging. In this paper, a two-granularity inspection-based software rejuvenation policy, which works as a closed-loop control technique, is proposed. This policy mitigates the negative impact of two-level software aging. The two levels considered are the user-level applications and the operating system. A Markov regenerative process model is constructed based on the system condition. We obtain the degradation rate of the application software and operating system from fault injection experiments. The diagnostic accuracy of the adopted monitor and analysis system, which is applied to inspect the application software and operating system, is considered as we provide the optimal rejuvenation strategies. Finally, the availability and the overall loss probability with their corresponding optimal inspection time intervals are obtained numerically based on the parameter values estimated from the experiments. Experimental results show that two-granularity software rejuvenation is much more effective than traditional single-level software rejuvenation. In our experi-mental study, when two-granularity software rejuvenation is used, the unavailability and the overall loss probability of the system were reduced by 17.9% and 2.65%, respectively, in comparison with the single-level rejuvenation. [ABSTRACT FROM PUBLISHER]

Disasters are inevitable, but their impact can be mitigated with careful planning. An IoT-based network with limited resources can be used in the post-disaster recovery. However, the resource of common interest creates contention among its contenders. This contention leads to tussle which in turn may lead to a deadlock. Some of the existing techniques prevent or avoid deadlock by performing stringent testing with significant testing overhead. While others propose recovery action after the deadlock is detected with significant overhead. A deadlock leads to a breakdown of the post-disaster recovery system while testing overhead implies delayed response either case can lead to catastrophic losses. This paper presents a new class of techniques that do not perform stringent testing before allocating the resources but still ensure that the system is deadlock-free and the overhead is also minimal. The proposed technique suggests reserving a portion of the resources to ensure no deadlock would occur. The correctness of the technique is proved in the form of theorems. The average turnaround time is approximately 18 % lower for the proposed technique over Banker's algorithm and also an optimal overhead of O (m). [ABSTRACT FROM AUTHOR]

This paper analyzes the phenomenon of software aging – namely, the gradual performance degradation and resource exhaustion in the long run – in the Android OS. The study intends to highlight if, and to what extent, devices from different vendors, under various usage conditions and configurations, are affected by software aging and which parts of the system are the main contributors. The results demonstrate that software aging systematically determines a gradual loss of responsiveness perceived by the user, and an unjustified depletion of physical memory. The analysis reveals differences in the aging trends due to the workload factors and to the type of running applications, as well as differences due to vendors' customization. Moreover, we analyze several system-level metrics to trace back the software aging effects to their main causes. We show that bloated Java containers are a significant contributor to software aging, and that it is feasible to mitigate aging through a micro-rejuvenation solution at the container level. [ABSTRACT FROM AUTHOR]

The design of Wireless Sensor Networks (WSN) requires the fulfillment of several design requirements. The most important one is optimizing the battery's lifetime, which is tightly coupled to the sensor lifetime. End-users usually avoid replacing sensors' batteries, especially in massive deployment scenarios like smart agriculture and smart buildings. To optimize battery lifetime, wireless sensor designers need to delineate and optimize active components at different levels of the sensor's layered architecture, mainly, (1) the number of data sets being generated and processed at the application layer, (2) the size and the architecture of the operating systems (OS), (3) the networking layers' protocols, and (4) the architecture of electronic components and duty cycling techniques. This paper reviews the different relevant technologies and investigates how they optimize energy consumption at each layer of the sensor's architecture, e.g., hardware, operating system, application, and networking layer. This paper aims to make the researcher aware of the various optimization opportunities when designing WSN nodes. To our knowledge, there is no other work in the literature that reviews energy optimization of WSN in the context of Smart Energy-Efficient Buildings (SEEB) and from the formerly four listed perspectives to help in the design and implementation of optimal WSN for SEEB. [ABSTRACT FROM AUTHOR]

Although many block replacement algorithms for buffer caches have been proposed to address the well-known drawbacks of the LRU algorithm, they are not robust and cannot maintain a consistent performance improvement over all workloads. This paper proposes a novel and simple replacement scheme, called the Robust Adaptive buffer Cache management schemE (RACE), which differentiates the locality of I/O streams by actively detecting access patterns that are inherently exhibited in two correlated spaces, that is, the discrete block space of program contexts from which I/O requests are issued and the continuous block space within files to which I/O requests are addressed. This scheme combines the global I/O regularities of an application and the local I/O regularities of individual files that are accessed in that application to accurately estimate the locality strength, which is crucial in deciding which blocks are to be replaced upon a cache miss. Through comprehensive simulations on 10 real-application traces, RACE is shown to have higher hit ratios than LRU and all other state-of-the-art cache management schemes studied in this paper. [ABSTRACT FROM AUTHOR]

This paper revisits a problem that was identified by Kramer and Magee: placing a system in a consistent state before and after runtime changes. We show that their notion of quiescence as a necessary and sufficient condition for safe runtime changes is too strict and results in a significant disruption in the application being updated. In this paper, we introduce a weaker condition: tranquillity. We show that tranquillity is easier to obtain and less disruptive for the running application but still a sufficient condition to ensure application consistency. We present an implementation of our approach on a component middleware platform and experimentally verify the validity and practical applicability of our approach using data retrieved from a case study. [ABSTRACT FROM AUTHOR]

An operating system course draws from a well-defined fundamental theory, but one needs to consider how more re- cent advances, not necessarily in the theory itself, can be applied to improve the course and the general body of knowledge of the student. The goal of this paper is to show how recent software engineering developments can be introduced to such a course to not only satisfy the theory requirements, but also make the theory more understandable. In particular, this paper focuses on how students can effectively learn the Unified Modeling Language, the object-oriented methodology, and the Java programming language in the context of an operating systems course. The goal is to form a systematic software engineering process for operating system design and implementation. [ABSTRACT FROM AUTHOR]

Real-time virtualization is currently a hot topic, and there is much ongoing research on real-time Virtual Machines and hypervisors. However, most of the previous research focused either on reducing the latencies introduced by the virtualization stack (hypervisor, host Operating System, Virtual Machine scheduling, etc...) or analyzing the virtual CPU scheduling algorithms. Only a few works investigated the impact of the guest Operating System architecture on real-time performance or considered multiple performance metrics (latency, schedulability, startup times, resource consumption) at the same time. This paper compares various features of different virtualization technologies and guest Operating Systems, evaluating their suitability for serving real-time applications. The results indicate that solutions based on KVM (and an appropriate microvm) and the OSv unikernel can be considered viable alternatives to more traditional VMs or containers. [ABSTRACT FROM AUTHOR]

The emerging hybrid DRAM-NVM architecture is challenging the existing memory management mechanism at the level of the architecture and operating system. In this paper, we introduce Memos, a memory management framework which can hierarchically schedule memory resources over the entire memory hierarchy including cache, channels, and main memory comprising DRAM and NVM simultaneously. Powered by our newly designed kernel-level monitoring module that samples the memory patterns by combining TLB monitoring with page walks, and page migration engine, Memos can dynamically optimize the data placement in the memory hierarchy in response to the memory access pattern, current resource utilization, and memory medium features. Our experimental results show that Memos can achieve high memory utilization, improving system throughput by around 20.0 percent; reduce the memory energy consumption by up to 82.5 percent; and improve the NVM lifetime by up to 34X. [ABSTRACT FROM AUTHOR]

A quick-response code (QR code) is a two-dimensional code akin to a barcode that encodes a message of limited length. In this paper, we present a variant of QR code, a two-layer QR code. Its two-layer structure can display two alternative messages when scanned from two different directions. We propose a method to generate such two-layer QR codes encoding two given messages in a few seconds. We also demonstrate the robustness of our method on both synthetic and fabricated examples. All source code will be made publicly available (https://github.com/yuantailing/two-layer-qrcode). [ABSTRACT FROM AUTHOR]

The use of remote desktop services on virtualized machines is a general trend to reduce the cost of desktop seats. Instead of assigning a physical machine with its operating system and software to each user, it is considerably easier to manage a light client machine that connects to a server where the instance of the user’s desktop machine actually executes. Citrix and VMware have been major suppliers of these systems in private clouds. Desktop-as-a-Service solutions such as Amazon WorkSpaces offer a similar functionality, yet in a public cloud environment. In this paper, we review the main offerings of remote desktop protocols for a cloud deployment. We evaluate the necessary network resources using a traffic model based on self-similar processes. We also evaluate the quality of experience perceived by the user, in terms of image quality and interactivity, providing values of Mean Opinion Score (MOS). The results confirm that the type of application running on the remote servers and the mix of users must be considered to determine the bandwidth requirements. Applications such as web browsing result in unexpectedly high traffic rates and long bursts, more than the case of desktop video playing, because the on-page animations are rendered on the server. [ABSTRACT FROM AUTHOR]