Time-sharing Operating System Research Articles

Revitalizing the single batch environment: a ‘Quest’ to achieve fairness and efficiency

In the realm of computer systems, efficient utilization of the CPU (Central Processing Unit) has always been a paramount concern. Researchers and engineers have long sought ways to optimize process execution on the CPU, leading to the emergence of CPU scheduling as a field of study. In this research, we have analyzed the single offline batch processing and investigated other sophisticated paradigms such as time-sharing operating systems and wildly used algorithms, and their shortcomings. Our work is directed toward two fundamental aspects of scheduling: efficiency and fairness. We propose a novel algorithm for batch processing that operates on a preemptive model, dynamically assigning priorities based on a robust ratio, employing a dynamic time slice, and utilizing periodic sorting to achieve fairness. By engineering this responsive and fair model, the proposed algorithm strikes a delicate balance between efficiency and fairness, providing an optimized solution for batch scheduling while ensuring system responsiveness.

Modified Round Robin with Highest Response Ratio Next CPU Scheduling Algorithm using Dynamic Time Quantum

Background: The most popular time-sharing operating systems scheduling technique, whose efficiency heavily dependent on time slice selection, is the round robin CPU scheduling algorithm. The time slice works similar to the First-Come-First-Serve (FCFS) scheduling or processor sharing algorithm if it is large or extremely too small. Some of the existing research papers have an algorithm called Improved Round Robin with Highest Response Ratio Next (IRRHRRN) which made use of response ratio with a predefined time quantum of 10ms with the major aim of avoiding starvation. However, the IRRHRRN algorithm favors processes with shorter burst time than the ones with longer burst time, and gave no regard to the process arrival time, thus leading to starvation. Aim: This study tries to improve on the IRRHRRN algorithm by proposing the Modified Round Robin with Highest Response Ratio Next (MRRHRRN) CPU Scheduling Algorithm using Dynamic Time Quantum in order to reduce the problem of starvation. Method: Dynamic method of determining the time quantum was adopted. Results: The proposed algorithm was compared with four other existing algorisms such as Standard Round Robin (RR), Improved Round Robin (IRR), An Additional Improvement in Round Robin (AAIRR), and the Improved Round Robin with Highest Response Ratio Next (IRRHRRN) and it provided some promising results in terms of the Average Waiting Time of 35407.6 ms, Average Turnaround Time of 36117.6 ms, Average Response Time of 10894.8 ms and Number of Context Switch of 301for the Non-Zero Arrival Times Processes

Operating system security with discrete mathematical structure for secure round robin scheduling method with intelligent time quantum

These days, the problems of scheduling and security are increasingly pressing as a result of the rapidly growing number of implementations that are operated in operating systems. Process scheduling and scheduling security is the most effective methodology of operating a system which can improve and degrade the performance of the computer system. The performance of scheduling algorithm in operating system can be measured by scheduling principles like average waiting time, average turnaround time, response time, throughput etc. Much research carried out over operating system security and round robin scheduling used in time sharing operating system in previous years to resolve the issues regarding to improvement in the performance of round robin (RR) scheduling and improving the security in the scheduling approach. This study discussed the security issues in operating systems, scheduling security and discrete structure of a new approach for RR scheduling. The researcher has suggested a list of policy for scheduling method security and proposed a new approach for RR scheduling and investigated the scheduling principles. The proposed methodology covers distinctive strategy for selection manner of process from ready queue than RR and used diverges time quantum. The proposed methodology has been validated experimentally by comparing with a numerous scheduling algorithm namely as Round Robin (RR), Adaptive Round Robin (ARR), Round Robin Remaining time (RRRT), improved Round Robin (IRR), an additional improvement on the improved Round Robin (AAAIRR), and an Enhanced Round Robin (ERR). Numerous simulations have been conducted to validate the effectiveness of the proposed algorithm to compelling the performance of system. At the conclusion the performance of computing system is dependent on security of operating system as well as secluding methods.

A new median-average round Robin scheduling algorithm: An optimal approach for reducing turnaround and waiting time

A variety of algorithms handles processes on the CPU. The round-robin algorithm is an efficient CPU scheduling mechanism for a time-sharing operating system. The system processes the methods based on the time slice; however, determining the time slice has proven highly challenging for the researchers. As a result, a variety of dynamic time quantum scheduling techniques are presented by various academics to address this challenge. This study aims to determine how to best schedule resources to maximize efficiency. It is important to note that this scheduling mechanism rotates between the processes after the static quantum time is complete. However, the quantum decision affects how effectively and efficiently the procedures may be scheduled. Additionally, the quantum decision has an impact on the scheduling of processes. The average waiting time, turnaround time, and context switch times of the Round Robin scheduling algorithm are high enough to influence the system's performance. To get over the round-drawbacks, robin's the authors in this study suggest using the improved algorithm Median-Average Round Robin (MARR). Using the median and average of the burst time of each process, the author proposes a dynamic time quantum for the system. The authors compared the proposed model with four other scheduling algorithms. The results vividly depict that the proposed algorithms successfully give effective results with reduced average turnaround time and waiting time. In the future, cost and RAM utilization will be considered to enhance the algorithm.

An Adjustable Variant of Round Robin Algorithm Based on Clustering Technique

CPU scheduling is the basic task within any time-shared operating system. One of the main goals of the researchers interested in CPU scheduling is minimizing time cost. Comparing between CPU scheduling algorithms is subject to some scheduling criteria (e.g., turnaround time, waiting time and number of context switches (NCS)). Scheduling policy is divided into preemptive and non-preemptive. Round Robin (RR) algorithm is the most common preemptive scheduling algorithm used in the time-shared operating systems. In this paper, the authors proposed a modified version of the RR algorithm, called dynamic time slice (DTS), to combine the advantageous of the low scheduling overhead of the RR and favor short process for the sake of minimizing time cost. Each process has a weight proportional to the weights of all processes. The process’s weight determines its time slice within the current period. The authors benefit from the clustering technique in grouping the processes that are similar in their attributes (e.g., CPU service time, weight, allowed time slice (ATS), proportional burst time (PBT) and NCS). Each process in a cluster is assigned the average of the processes’ time slices in this cluster. A comparative study of six popular scheduling algorithms and the proposed approach on nine groups of processes vary in their attributes was performed and the evaluation was measured in terms of waiting and turnaround times, and NCS. The experiments showed that the proposed algorithm gives better results.

Dynamic Round Robin CPU Scheduling Algorithm Based on K-Means Clustering Technique

Minimizing time cost in time-shared operating system is the main aim of the researchers interested in CPU scheduling. CPU scheduling is the basic job within any operating system. Scheduling criteria (e.g., waiting time, turnaround time and number of context switches (NCS)) are used to compare CPU scheduling algorithms. Round robin (RR) is the most common preemptive scheduling policy used in time-shared operating systems. In this paper, a modified version of the RR algorithm is introduced to combine the advantageous of favor short process and low scheduling overhead of RR for the sake of minimizing average waiting time, turnaround time and NCS. The proposed work starts by clustering the processes into clusters where each cluster contains processes that are similar in attributes (e.g., CPU service period, weights and number of allocations to CPU). Every process in a cluster is assigned the same time slice depending on the weight of its cluster and its CPU service period. The authors performed comparative study of the proposed approach and popular scheduling algorithms on nine groups of processes vary in their attributes. The evaluation was measured in terms of waiting time, turnaround time, and NCS. The experiments showed that the proposed approach gives better results.

From facilitating interactivity to managing hyperconnectivity: 50 years of human–computer studies

Abstract Five decades ago advances in integrated circuits and time-sharing operating systems made interactive use of computers economically feasible. Visions of man-computer symbiosis and the augmentation of man’s intellect became realistic research objectives. The initial focus was on facilitating interactivity through improved interface technology, and supporting its application through good practices based on experience and psychological principles. Within a decade technology advances made low cost personal computers commonly available in the home, office and industry, and these were rapidly enhanced with software that made them attractive in a wide range of applications from games to office automation and industrial process control. Within three decades the Internet enabled human–computer interaction to extend across local, national and international networks, and, within four, smartphones and tablets had made access to computers and networks almost ubiquitous to any person, at any time and any place. Banking, commerce, institutional and company operations, utility and government infrastructures, took advantage of, and became dependent on, interactive computer and networking capabilities to such an extent that they have now been assimilated in our society and are taken for granted. This hyperconnectivity has been a major economic driver in the current millennium, but it has also raised new problems as malevolent users anywhere in the world have become able to access and interfere with critical personal, commercial and national resources. A major issue for human–computer studies now is to maintain and enhance functionality, usability and likeability for legitimate users whilst protecting them from malevolent users. Understanding the issues involved requires a far broader consideration of socio-economic issues than was required five decades ago. This article reviews various models of the role of technology in human civilization that can provide insights into our current problematique.

Development of brain function theory and the frontier brain projects

The governments of several countries have funded frontier brain projects in recent years, which thus raises important questions about the brain and brain research. What have we known about brain function and the recent development of brain function theory? How are the frontier brain projects developing? This article reviews the development of brain function theories from an interdisciplinary perspective and introduces three frontier brain projects. The functions of the prefrontal cortex, especially, the medial prefrontal cortex, and the mirror neuron system as well as default-mode network (DMN) have been extensively investigated since the beginning of the 21th century. The findings have expanded brain functional systems from the specific nervous system and nonspecific reticular system to four major brain function systems including specific, nonspecific, socio-cognitive, and DMN systems. The specific nervous system coordinates and cooperates with the nonspecific reticular system; the former represent an efficiently reflective action to stimulation only when the later provides an adaptive arousal. A time sharing operating system consists of the DMN and socio-cognitive system with a 180-degree phase difference between the two systems. The former performs any socio-cognitive task whereas the later only prepares for a new task. There is a common principle between localization theory of brain function and equipotentiality theory of brain function which applies to the four brain function systems. There are four principles for neural information processing: the principle of simultaneous existence of digital encoding and analog encoding, the principle of the simultaneous existence of multi-processing processes and multi-information streams, the principle of circular permutation and coupling between electrical transmit and biochemical transmit in processing of neural information, and the principle of relevance between neural and genetic information. The principles of brain functions based on protein are different from those of artificial machines based on electricity. Artificial intelligent machines do not work as well as biological system in complicated ecological environments, because due to the lack of the last two information processing principles. The unique features of the human brain are manifested in the integration of biological and social attributes, and its hierarchical modules as well as the containment among the modules. The uniqueness of human brain is not only represented in the big prefrontal cortex but also the hierarchical modules that have been precipitated in different time axes from 3.5 billion years of biological evolution to near 100 years of a person’s life span. The highest level is individual’s social conscious module including the mirror neural system and the theory of mind module (ToMM). The unique modules are developed starting from the 4th year. The functional principle of the matured health human brain is shaped by individuals’ socio-cultural experiences. Either artificial intelligent machines or animal intelligence lacks human socio-cultural environments, and thus the animal brain comprised of 3 hierarchical modules. The three frontier brain projects that are respectively characterized by marcroscopic, microscopic, and mesoscopic mapping include the brain connectome, brain activity map(BMP), and China Brain Project. Connectome project studies both brain structural and functional networks based on brain imaging data. BMP explores molecular or neuronal mechanisms of behavior based on new techniques in molecular biology and cell biology. China Brain Project aims to fill out the gaps between macro- and microscopic investigating project, based on new technique, to display a whole neuron connectome.

Fernando Corbató: Time-Sharing Pioneer, Part 2

Fernando Corbató: Time-Sharing Pioneer, Part 2 Dag Spicer (bio) Fernando Corbató is likely best known for his work developing time-sharing operating systems. Early in his career, Corbató had a pioneering role in the development of both the Compatible Time-Sharing System (CTSS) and Multics at the Massachusetts Institute of Technology. The second in a two-part series, the following interview is based on an oral history conducted by Steven Webber for the Computer History Museum in February 2006. (For a full transcript, see the CHM archive: http://archive.computerhistory.org/resources/text/Oral_History/Corbato_Fernando/Corbato_Fernando_1.oral_history.2006.102658041.pdf.) Steven Webber: Let’s get back to the summer of 1963. You mentioned the Project MAC summer program. What’s the actual timeframe on Project MAC? Fernando Corbató: J.C.R. Licklider, who had once been a professor at MIT, was at Lincoln Laboratories and he got his hands on some computers there. He was fascinated with the programming experience and ended up going to BBN (Bolt, Beranek and Newman), where he wanted to build a time-sharing system. A lot of efforts were ongoing to create time-sharing systems then, including the Dartmouth time-sharing system. The BBN system had a four-person team: John McCarthy was one of them, primarily as an adviser, and Ed Fredkin and Shelly Boilen, along with Licklider. They tried to create a simple time-sharing system based on the DEC PDP-1 computer, which was the first of the minicomputers. Today we’d call it a personal computer, but it was still a relatively big box. They got that system going in approximately the summer of 1962. For a long time, they bragged that they were first until I pointed out to them that we had demonstrated ours in 1961, but these are small details. McCarthy was promoting time-sharing along with Licklider at BBN, and Licklider then got recruited by ARPA to embark on a program encouraging “man-machine interaction.” The story I heard was that the Cuban Missile Crisis in 1961 had shocked the Pentagon because they discovered that a lot of their information systems were practically unusable. They couldn’t get information fast enough, and they were crashing. It was just a mess. They were so shocked that they had such poor man-machine interaction with their computers, their communication systems, their databases, and the like that they wanted to start research to improve on this and get better tools for the military’s purposes. So after Lick got recruited he began to travel around trying to encourage people to embark on time-sharing, and he came to MIT to see if anybody was interested. Webber: Was this after you had already demonstrated CTSS? Corbató: I’m not sure. We were certainly about to demonstrate, but the key thing is that Bob Fano, myself, Doug Ross, and about a half dozen or so of us who were participants in the computing activities at MIT were at this meeting with Licklider. Licklider started to ask us what we wanted, what we would think about doing, but it was like a catfight. Everybody had his or her own notion or plan or scheme. Licklider took it in stride, but we were dismayed by our behavior in front of this potential sponsor who wanted to give us money to do something. We were so disorganized. It was disgraceful. Fano came back from that meeting and recognized that there was a lack of leadership at MIT. He thought about it and subsequently had a long train ride with Lick coming back from a meeting in Hot Springs, Virginia. I think Fano would claim that he was persuaded to go ahead when he came back from that meeting. He decided that he would start to organize a venture that came to be called Project MAC. That formative stage was in the fall of 1962. Bob made the decision that we would use CTSS as a prototype for Project MAC to exhibit time-sharing, and we would do that by getting a carbon copy of the machine at the Computation Center. I think they placed the order just around the turn of the year, 1962...

Fernando Corbató: Time-Sharing Pioneer, Part 2

Fernando Corbato is best known for his work developing time-sharing operating systems. Early in his career, Corbato had a key role in the development of both the Compatible Time-Sharing System (CTSS) and Multics at the Massachusetts Institute of Technology in the 1960s. This interview is the second in a two-part Annals series based on an oral history conducted by Steven Webber for the Computer History Museum in February 2006.

Fernando Corbató: Time-Sharing Pioneer, Part 1

Fernando Corbato is best known his work developing time-sharing operating systems. Early in his career, Corbato had a key role in the development of both the Compatible Time-Sharing System (CTSS) and Multics at the Massachusetts Institute of Technology in the 1960s. In 1990, Corbato received the Turing Award for his pioneering work in organizing the concepts and leading the development of the general-purpose, large-scale, time-sharing and resource-sharing computer systems, and he was made a fellow of the Computer History Museum (CHM) in 2012. This interview is the first in a two-part Annals series based on an oral history conducted by Steven Webber the CHM in February 2006.

Performance Tuning Towards a KVM-based Embedded Real-time Virtualization System

Virtualization is a fundamental component in cloud computing because it provides numerous guest VM transparent services, such as live migration, high availability, rapid checkpoint, etc. Utilizing virtualization technology to combine real-time operating system (RTOS) and off-the-shelf time-sharing general purpose operating system (GPOS) is attracting much more interest recently. Such combination has the potential to provide a large application base, and to guarantee timely deterministic response to real-time applications, yet there remain some issues, such as responsiveness of RTOS running on top of a virtual machine (VM), system performance and CPU resource utilization rate, etc. In this paper we propose an embedded real-time virtualization architecture based on Kernel- Based Virtual Machine (KVM), in which VxWorks and Linux are combined together. We then analyze and evaluate how KVM influences the interrupt-response times of VxWorks as a guest operating system. By applying several real-time performance tuning methods on the host Linux, we will show that sub-millisecond interrupt response latency can be achieved on the guest VxWorks. Furthermore, we also find out that prioritization tuning results in waste of CPU resources when RTOS is not executing real-time tasks, so we design a dynamic scheduling mechanism--co-scheduling to improve system performance. Experimental results with SPEC2000 and bonnie 1.4 load, show that this new architecture tuned by CPU shielding, prioritization and co-scheduling, can achieve better real-time responsiveness and system performance.

A Group based Time Quantum Round Robin Algorithm using Min-Max Spread Measure

Round Robin (RR) Scheduling is the basis of time sharing environment. It is the combination of First Come First Served (FCFS) scheduling algorithm and preemption among processes. It is basically used in a time sharing operating system. It switches from one process to another process in a time interval. The time interval or Time Quantum (TQ) is fixed for all available processes. So, the larger process suffers from Context Switches (CS). To increase efficiency, we have to select different TQ for processes. The main objective of RR is to reduce the CS, maximize the utilization of CPU and minimize the turn around and the waiting time. In this paper, we have considered different TQ for a group of processes. It reduces CS as well as enhancing the performance of RR algorithm. TQ can be calculated using min-max dispersion measure. Our experimental analysis shows that Group Based Time Quantum (GBTQ) RR algorithm performs better than existing RR algorithm with respect to Average Turn Around Time (ATAT), Average Waiting Time (AWT) and CS.

Scarce resources in computing

How we organize computing - and innovate with it - is shaped by what at any time is the most scarce resource. In the early days of computing, processing (and, to a certain extent, storage, which up to a point is a substitute for processing) was the main scarce resource. Computers were expensive and weak, so you had to organize what you did with them to make as much out of the processing capacity as possible. Hence, with the early computers, much time was spent making sure the process was fully used, by meticulously allocating time for users on the machine - first with scheduled batch processing, then with time-sharing operating systems that rationed processing resources to users based on need and budget.

Synchronization resources in heterogeneous environments: Time-sharing, real-time and Java

The asynchronous event distribution system (AEDS) was built to provide synchronization resources within the TJ-II local area network. It is a software system developed to add “soft synchronization” capabilities to the TJ-II data acquisition, control and analysis environments. “Soft synchronization” signifies that AEDS is not a real-time system. In fact, AEDS is based on TCP/IP over ETHERNET networks. However, its response time is adequate for practical purposes when synchronization requirements can support some delay between event dispatch and message reception. Event broadcasters (or synchronization servers in AEDS terminology) are Windows computers. Destination computers (or synchronization clients) were also Windows machines in the first version of AEDS. However, this fact imposed a very important limitation on synchronization capabilities. To overcome this situation, synchronization clients for different environments have been added to AEDS: for time-sharing operating systems (Unix and Linux), real-time operating systems (OS-9 and VxWorks) and Java applications. These environments have different synchronization primitives, requiring different approaches to provide the required uniform functionality. This has been achieved with POSIX thread library synchronization primitives (mutex and condition variables) on Unix/Linux systems, IPC mechanisms for concurrent processes on OS-9 and VxWorks real-time operating systems, and ‘synchronized–wait/notify’ primitives on Java virtual machines.

Nonclairvoyant scheduling to minimize the total flow time on single and parallel machines

Scheduling a sequence of jobs released over time when the processing time of a job is only known at its completion is a classical problem in CPU scheduling in time sharing operating systems. A widely used measure for the responsiveness of the system is the average flow time of the jobs, that is, the average time spent by jobs in the system between release and completion.The Windows NT and the Unix operating system scheduling policies are based on the Multilevel Feedback algorithm. In this article, we prove that a randomized version of the Multilevel Feedback algorithm is competitive for single and parallel machine systems, in our opinion providing one theoretical validation of the goodness of an idea that has proven effective in practice along the last two decades.The randomized Multilevel Feedback algorithm (RMLF) was first proposed by Kalyanasundaram and Pruhs for a single machine achieving an O (log n log log n ) competitive ratio to minimize the average flow time against the on-line adaptive adversary, where n is the number of jobs that are released. We present a version of RMLF working for any number m of parallel machines. We show for RMLF a first O (log n log n / m ) competitiveness result against the oblivious adversary on parallel machines. We also show that the same RMLF algorithm surprisingly achieves a tight O (log n ) competitive ratio against the oblivious adversary on a single machine, therefore matching the lower bound for this case.

Implementing an untrusted operating system on trusted hardware

Recently, there has been considerable interest in providing "trusted computing platforms" using hardware~---~TCPA and Palladium being the most publicly visible examples. In this paper we discuss our experience with building such a platform using a traditional time-sharing operating system executing on XOM~---~a processor architecture that provides copy protection and tamper-resistance functions. In XOM, only the processor is trusted; main memory and the operating system are not trusted.Our operating system (XOMOS) manages hardware resources for applications that don't trust it. This requires a division of responsibilities between the operating system and hardware that is unlike previous systems. We describe techniques for providing traditional operating systems services in this context.Since an implementation of a XOM processor does not exist, we use SimOS to simulate the hardware. We modify IRIX 6.5, a commercially available operating system to create xomos. We are then able to analyze the performance and implementation overheads of running an untrusted operating system on trusted hardware.

Minimizing flow time nonclairvoyantly

We consider the problem of scheduling a collection of dynamically arriving jobs with unknown execution times so as to minimize the average flow time. This is the classic CPU scheduling problem faced by time-sharing operating systems where preemption is allowed. It is easy to see that every algorithm that doesn't unnecessarily idle the processor is at worst n -competitive, where n is the number of jobs. Yet there was no known nonclairvoyant algorithm, deterministic or randomized, with a competitive ratio provably O ( n 1−ϵ ). In this article, we give a randomized nonclairvoyant algorithm, RMLF, that has competitive ratio O (log n log log n ) against an oblivious adversary. RMLF is a slight variation of the multilevel feedback (MLF) algorithm used by the UNIX operating system, further justifying the adoption of this algorithm. It is known that every randomized nonclairvoyant algorithm is Ω(log n )-competitive, and that every deterministic nonclairvoyant algorithm is Ω( n 1/3 )-competitive.

Implementing Real-Time Scheduling in a Time-Sharing Operating System

In this work, the results of a project devoted to provide programming facilities to develop hard real-time software are presented. MINIX operating system has been used as a tool for the experience. The programmer is allowed to define timing constraints for the tasks, letting to the operating system the work of running them in a timely fashion. In this way, productivity, security and costs in the development cycle can be improved. The schedulers can be easily changed, providing a framework to test new scheduling solutions.

Nonclairvoyant scheduling

Virtually all research in scheduling theory has been concerned with clairvoyant scheduling where it is assumed that the characteristics of a job (in particular, its execution time, release time and dependence on other jobs) are known a priori. This assumption is invalid for scheduling problems that arise in time-sharing operating systems where the scheduler must provide fast turnaround for processes being generated by the users without any knowledge of the future behavior of these processes. We study preemptive, nonclairvoyant scheduling schemes where the scheduler has no knowledge of the jobs' characteristics. We develop a model for evaluating scheduling strategies for single and multiprocessor systems. This model compares the nonclairvoyant scheduler against the optimal clairvoyant scheduler, and it takes into account various issues such as release time, execution time, preemption cost, and the inter-dependence between jobs. Within this model we study some standard scheduling algorithms described in the systems literature, and we provide some theoretical justification for their effectiveness in practice by presenting some randomized and deterministic upper and lower bounds.