Computer Operating System Research Articles

Platform Contracting and Exclusivity

Platforms care about the quality of components they host. For example, a computer operating system is more popular - and thus more profitable - when the software is high quality. Some platforms offer special arrangements to high-quality firms - for example, Apple promotes high-quality Macintosh software on the Apple website. Others shut out low-quality firms completely. Nintendo has established a reputation for screening out low quality games from their game console. Finally, some platforms require exclusive contracts, whereby a component cannot be made available on any other platform, many TV sports programming contracts are designed this way. We study the contract design options of a platform owner offering a screening contract to a component developer who should be incentivized to deliver a particular quality level. When dealing both with adverse selection (component quality types are not known to the platform ex ante) and moral hazard (efforts to improve the component or offer customer service are not observable to the platform), the platform will use additional allocative distortion compared to the standard screening contract. Of particular interest is our finding that under exclusivity, when high-quality components require a higher participation rent, there is less allocative distortion, permitting a new interpretation of countervailing incentives in a platform-contracting environment.

NOX

As anyone who has operated a large network can attest, enterprise networks are difficult to manage. That they have remained so despite significant commercial and academic efforts suggests the need for a different network management paradigm. Here we turn to operating systems as an instructive example in taming management complexity. In the early days of computing, programs were written in machine languages that had no common abstractions for the underlying physical resources. This made programs hard to write, port, reason about, and debug. Modern operating systems facilitate program development by providing controlled access to high-level abstractions for resources (e.g., memory, storage, communication) and information (e.g., files, directories). These abstractions enable programs to carry out complicated tasks safely and efficiently on a wide variety of computing hardware. In contrast, networks are managed through low-level configuration of individual components. Moreover, these configurations often depend on the underlying network; for example, blocking a user’s access with an ACL entry requires knowing the user’s current IP address. More complicated tasks require more extensive network knowledge; forcing guest users’ port 80 traffic to traverse an HTTP proxy requires knowing the current network topology and the location of each guest. In this way, an enterprise network resembles a computer without an operating system, with network-dependent component configuration playing the role of hardware-dependent machine-language programming. What we clearly need is an “operating system” for networks, one that provides a uniform and centralized programmatic interface to the entire network. Analogous to the read and write access to various resources provided by computer operating systems, a network operating system provides the ability to observe and control a network. A network operating system does not manage the network itself; it merely provides a programmatic interface. Applications implemented on top of the network operating system perform the actual management tasks. The programmatic interface should be general enough to support a broad spectrum of network management applications. Such a network operating system represents two major conceptual departures from the status quo. First, the network operating system presents programs with a centralized programming model; programs are written as if the entire network were present on a single machine (i.e., one would use Dijkstra to compute shortest paths, not Bellman-Ford). This requires (as in [3, 8, 14] and elsewhere) centralizing network state. Second, programs are written in terms of high-level abstractions (e.g., user and host names), not low-level configuration parameters (e.g., IP and MAC addresses). This allows management directives to be enforced independent of the underlying network topology, but it requires that the network operating system carefully maintain the bindings (i.e., mappings) between these abstractions and the low-level configurations. Thus, a network operating system allows management applications to be written as centralized programs over highlevel names as opposed to the distributed algorithms over low-level addresses we are forced to use today. While clearly a desirable goal, achieving this transformation from distributed algorithms to centralized programming presents significant technical challenges, and the question we pose here is: Can one build a network operating system at significant scale?

Program for calculating SU(4) Clebsch–Gordan coefficients

The SU(4) Clebsch–Gordan coefficients of the decomposition { N a } ⊗ { N b } → { N } are calculated for arbitrary irreducible representations { N a } , { N b } and { N } . They are efficiently computed for the group chain SU(4) ⊃ SU(3)×U(1) ⊃ SU(2)×U(1) ⊃ U(1) using the eigenfunction method along with recurrence relations. Program summary Program title: CGSU4 Catalogue identifier: AEBL_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEBL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2847 No. of bytes in distributed program, including test data, etc.: 23 794 Distribution format: tar.gz Programming language: Fortran 95 Computer: Personal computer Operating system: Linux, Windows RAM: 2 MB Classification: 4.2 Subprograms used: ACRM_v1_0; Title: SU(3) [1] Nature of problem: The SU(4) Clebsch–Gordan coefficients according to the group chain SU(4) ⊃ SU(3) × U(1) ⊃ SU(2) × U(1) ⊃ U(1) are calculated for arbitrary couplings. Solution method: The eigenfunctions method in combination with recurrence relations is used to generate tables of the SU(4) ⊃ SU(3) × U(1) isoscalar factors for the decomposition { N a } ⊗ { N b } → { N } γ with the multiplicity label γ. The SU(4) Clebsch–Gordan coefficients are then composed by these isoscalar factors and SU(3) Clebsch–Gordan coefficients according to the Racah factorization lemma. Restrictions: The dimensions of the involved representations are limited by the size of the arrays defined in the program. Additional comments: If many Clebsch–Gordan coefficients are needed for the same decomposition { N a } ⊗ { N b } → { N } γ , the running time is significantly reduced if the table of isoscalar factors is calculated only once. The SU(3) code [1] and the code for eigen, a matrix diagonalization program (IBM scientific subroutine package) are included in the CGSU4 code package. Running time: The running time sensitively depends on the specific Clebsch–Gordan decomposition and the dimensions of the involved representations, varying from parts of a second to a minute.

Guest Editors' Introduction: Interaction of Many-Core Computer Architecture and Operating Systems

Rapid changes in platform hardware resources with the evolution of many-core architectures will require a fundamental reexamination of mainstream system-software design decisions to support multiple cores and to efficiently manage on-chip hardware resources shared among the multiple cores. In turn, the evolution of many-core processor architectures will be successfully sustained by the new capabilities and features added to the system software, perhaps while requiring substantial support from hardware. The guest editors introduce five articles on the interaction of computer architecture and operating systems for this special issue of IEEE Micro.

Consumer Electronics Show and Macworld

THE CONSUMER Electronics Show (CES) and Macworld, both held in January, are always a rich source of information about where the electronics industry is headed. Based on this year's shows, it appears that the future will be wireless, thin, high-definition, and chic. One of the annual events at CES is the last gadget standing, an informal contest sponsored by Yahoo. The winner of this year's competition was the Eye-Fi wireless SD (secure digital) card. The Eye-Fi card is a two-GB memory card with a built-in wireless Wi-Fi transmitter. With the software included, you can wirelessly transfer photos to your computer or even to an Internet photo-sharing site. The card is available from Wal-Mart and other retailers for about $100. Speaking of wireless, several new technologies are becoming available that can help eliminate wires. Universal Serial Bus (USB) 2.0 has become the ubiquitous standard for computer interfaces. Now, there is Wireless USB. Wireless USB is essentially an in-room technology that creates a wireless interface between devices over a distance from 3 to 10 meters. At 3 meters, the data transfer rate is as high as 480 Mbps (megabits per second). At 10 meters, the transfer rate drops to 110 Mbps. These rates make it possible to connect printers and other peripherals and transfer photos and music, but they are not fast enough to transmit high-resolution video very well. If you hate wires, the under-$50 price tag is appealing. However, you will need an adapter for every device. Recently an industry trade group formed called Certified Wireless USB. The group has an informative website at www.usb.org. Of course, before you buy any Wireless USB devices, it is wise to be sure the company has drivers for your computer's operating system and for your printers. Recent reports have come in that drivers are slow in coming for Microsoft Windows Vista. Another industry trade group dedicated to developing wireless networks capable of streaming high-definition video and surround sound is called WirelessHD (WiHD). Members of the group include LG Electronics, Matsushita, NEC, Samsung, Sony, and Toshiba. If you want to beam high-definition video (HDTV) with surround sound all through the house--something I have wanted to do for years--things get tricky. Beaming four streams of HDTV is ideal, since different people in different rooms could then watch different programming. But unlike Web browsing and other wireless uses, even small interruptions in a video stream are objectionable. This means that the gear used must have what is known as a QoS (quality of service) function that guarantees a certain throughput. By comparison to Wireless USB, WirelessHD has data transfer rates of between 2 and 5 Gbps (gigabits per second). WiHD is definitely an in-room technology, but that may be a benefit. You won't be beaming your video around the neighborhood. If you are interested in learning more about WirelessHD, Wikipedia (http://en.wikipedia.org) has good explanations and comparisons of various approaches. I suspect that, by the end of 2008, both Wireless USB and WirelessHD will have become common. They say that is in, and in the IT world, thin was readily apparent at this year's shows. For example, LG previewed a super-thin 42 LCD HDTV that is only 1.7 thick. Not to be outdone, Sony unveiled an 11 television that is only 3 mm thick. Sony's super-thin TV uses an OLED (organic light emitting diode), a technology that requires very little power. By contrast, LCD and plasma displays consume a lot of electricity, so OLED is a step toward greener displays. The ASUS Eee PC is a sub-notebook or ultra-compact PC that has received a lot of attention at CES and in the tech press. The Eee is the size of a hardback book and has a 7 diagonal screen with a resolution of 800 x 480 pixels. A distinguishing feature of the Eee is that it uses memory chips instead of a hard drive. …

The battle behind the scenes

Like Stuart Lynn, I had been a department editor for CACM before becoming its EIC. In fact, the "Computer Systems" department was initiated by Kelly Gotlieb during his editorship. He sent me a letter enclosing a submitted paper that he thought should be published in CACM; however, it fit no existing department. It would appear in the September 1965 issue: Reilly and Federighi's "On Reversible Subroutines and Computers that Run Backwards." A subsequent contribution, of considerably more lasting significance, was published in that same issue: E.W. Dijkstra's "Solution of a Problem in Concurrent Program Control." Indeed, the paper initiated a whole new subdiscipline in the computer operating systems area. Eventually, "Computer Systems" became the department for software/hardware systems papers such as those that now appear in Transactions on Computer Systems (TOCS) .

Soft Synchronization: Synchronization for Network-Connected Machine Vision Systems

Many computer vision applications require synchronization between image acquisition and external trigger events. Hardware and software triggering are widely used but have several limitations. Soft synchronization is investigated, which operates by time tagging both trigger events and images in a video stream and selecting the image corresponding to each trigger event. A stochastic model is developed for soft synchronization; and, based on the model, the uncertainty interval and confidence for correct image selection are determined, and an efficient calibration method is derived. Soft synchronization is experimentally demonstrated on a Linux image processing computer with a camera connected by the IEEE-1394 serial bus. To minimize timing variability, time tags are associated with images and events in the corresponding interrupt service routines within the operating system of the image processing computer. The model-based analysis applied to the experimental hardware shows that image/event synchronization within inter-frame interval can be achieved with 99% confidence. Experiments confirm this result.

Model Checking Abilities of Agents: A Closer Look

Alternating-time temporal logic (atl) is a logic for reasoning about open computational systems and multi-agent systems. It is well known that atl model checking is linear in the size of the model. We point out, however, that the size of an atl model is usually exponential in the number of agents. When the size of models is defined in terms of states and agents rather than transitions, it turns out that the problem is (1) Δ3P-complete for concurrent game structures, and (2) Δ2P-complete for alternating transition systems. Moreover, for “Positive atl” that allows for negation only on the level of propositions, model checking is (1) Σ2P-complete for concurrent game structures, and (2) NP-complete for alternating transition systems. We show a nondeterministic polynomial reduction from checking arbitrary alternating transition systems to checking turn-based transition systems, We also discuss the determinism assumption in alternating transition systems, and show that it can be easily removed. In the second part of the paper, we study the model checking complexity for formulae of atlwith imperfect information (atlir). We show that the problem is Δ2P-complete in the number of transitions and the length of the formula (thereby closing a gap in previous work of Schobbens in Electron. Notes Theor. Comput. Sci. 85(2), 2004). Then, we take a closer look and use the same fine structure complexity measure as we did for atl with perfect information. We get the surprising result that checking formulae of atlir is also Δ3P-complete in the general case, and Σ2P-complete for “Positive atlir”. Thus, model checking agents’ abilities for both perfect and imperfect information systems belongs to the same complexity class when a finer-grained analysis is used.

Activity-based scenarios for and approaches to ubiquitous e-Learning

This paper presents scenarios for ubiquitous e-Learning in heterogeneous networks. It concludes by arguing for the development of a learning-focused analogue, activity-based e-Learning extensions (ABLE), of activity-based computing (ABC). The goal would be to offer the learning-support/performance-support equivalent of ABC's support for human activities in a ubiquitous computing environment, relevant to areas that are hard to model today: informal on-the-job learning; peer-to-peer support and informal sharing of content in ad hoc work groups; formal and informal ways to capture and share knowledge-focused insights and processes; content and systems to aid reflection. Just as ABC supplements traditional computing approaches (in ABC, data- and application-oriented) to suit "multiple, parallel and mobile work activities" (Bardram et al. in Support for ABC in a personal computing operating system. CHI 2006 proceedings. Montreal, Quebec, Canada, 22---27 April 2006, pp 211---220), so ABLE could supplement traditional e-Learning approaches (often largely content-focused, sometimes little more than page-turning) to suit those same work activities, and make e-Learning potentially more resilient to interruptions, more fun and more memorable.

Random walk analysis of parallel queueing stations

We analyze a complex stochastic system with a single server who operates in two parallel stations. The server works in station I until the input to station I slows down. Then the server switches to station II processing a queue of jobs there and then returns to station I upon finishing the total work in station II. If during his service in station II the input to station I becomes intense so that the queue of jobs there get alarmingly long, the server begins to process two queues simultaneously. Then, dependent on the situation, the server either continues with the rest of the jobs in station II or returns to station I and rests there until its buffer fills up to a certain level prompting him to resume his service. During various switchovers, the server changes his modes, each time engaging in different distributions. The switchovers are managed at first passage times of a multivariate random walk exiting relevant sets. We use and embellish methods of fluctuation analysis for multivariate random walks to investigate the queueing processes. This enables us to arrive at closed-form functionals for the processes and related random components. Applications are found in computer networking and operating systems analysis.

DAMARIS — a flexible and open software platform for NMR spectrometer control

Home-built NMR spectrometers with self-written control software have a long tradition in porous media research. Advantages of such spectrometers are not just lower costs but also more flexibility in developing new experiments (while commercial NMR systems are typically optimized for standard applications such as spectroscopy, imaging or quality control applications). Increasing complexity of computer operating systems, higher expectations with respect to user-friendliness and graphical user interfaces as well as increasing complexity of the NMR experiments themselves have made spectrometer control software development a more complex task than it used to be some years ago. Like that, it becomes more and more complicated for an individual lab to maintain and develop an infrastructure of purely homebuilt NMR systems and software. Possible ways out are: ● commercial NMR hardware with full-blown proprietary software or ● semistandardized home-built equipment and common open-source software environment for spectrometer control. Our present activities in Darmstadt aim at providing a nucleus for the second option: DArmstadt MAgnetic Resonance Instrument Software (DAMARIS) [1]. Based on an ordinary PC, pulse control cards and ADC cards, we have developed an NMR spectrometer control platform that comes at a price tag of about 8000 Euro. The present functionalities of DAMARIS are mainly focused on TD-NMR: the software was successfully used in single-sided NMR [2], pulsed and static field gradient NMR diffusometry [3]. Further work with respect to multipulse/multitriggering experiments in the time domain [4] and solid state NMR spectroscopy multipulse experiments are under development.

HoloTrap: Interactive hologram design for multiple dynamic optical trapping

This work presents an application that generates real-time holograms to be displayed on a holographic optical tweezers setup; a technique that allows the manipulation of particles in the range from micrometres to nanometres. The software is written in Java, and uses random binary masks to generate the holograms. It allows customization of several parameters that are dependent on the experimental setup, such as the specific characteristics of the device displaying the hologram, or the presence of aberrations. We evaluate the software's performance and conclude that real-time interaction is achieved. We give our experimental results from manipulating 5 μm microspheres using the program. Program summary Title of program: HoloTrap Catalogue identifier:ADZB_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/ADZB_v1_0 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer for which the program is designed and others on which it has been tested: General computer Operating systems or monitors under which the program has been tested: Windows, Linux Programming language used: Java Memory required to execute with typical data: up to 34 MB including the Java Virtual Machine No. of bits in a word: 8 bits No. of processors used: 1 Has the code been vectorized or parallelized?: No No. of lines in distributed program, including test data, etc.: 471 145 No. of bytes in distributed program, including test data, etc.: 1 141 457 Distribution format: tar.gz Nature of physical problem: To calculate and display holograms for generating multiple and dynamic optical tweezers to be reconfigured interactively. Method of solution: Fast random binary mask for the simultaneous codification of multiple phase functions into a phase modulation device. Typical running time: Up to 10 frames per second Unusual features of the program: None

Mindstorms without robotics

This paper examines the applicability of LEGO Mindstorms to the intermediate-level computer science curriculum, which traditionally includes courses such as Computer Organization and Operating Systems. We describe three open-laboratory projects that employ Mindstorms in exploring systems-level programming topics and present results from student evaluations of the projects over the last two years. An interesting feature of the projects is that they do not involve robotics or robot construction but instead focus on the Mindstorms programmable brick as a platform in its own right.

The physiology analysis system: An integrated approach for warehousing, management and analysis of time-series physiology data

The physiology analysis system (PAS) was developed as a resource to support the efficient warehousing, management, and analysis of physiology data, particularly, continuous time-series data that may be extensive, of variable quality, and distributed across many files. The PAS incorporates time-series data collected by many types of data-acquisition devices, and it is designed to free users from data management burdens. This Web-based system allows both discrete (attribute) and time-series (ordered) data to be manipulated, visualized, and analyzed via a client's Web browser. All processes occur on a server, so that the client does not have to download data or any application programs, and the PAS is independent of the client's computer operating system. The PAS contains a library of functions, written in different computer languages that the client can add to and use to perform specific data operations. Functions from the library are sequentially inserted into a function chain-based logical structure to construct sophisticated data operators from simple function building blocks, affording ad hoc query and analysis of time-series data. These features support advanced mining of physiology data.

PGO: A parallel computing platform for global optimization based on genetic algorithm

This paper presents the design, architecture and implementation of a general parallel computing platform, termed PGO, based on the Genetic Algorithm (GA) for global optimization. PGO provides an efficient and easy-to-use framework for parallelizing the global optimization procedure for general scientific modeling and simulation processes. Along with a core optimization kernel built on a GA, PGO also includes a general input generator and an output extractor that can facilitate its easy integration with various scientific computing tasks. In this paper, we demonstrate the efficiency and versatility of PGO with two different applications: (1) the parallelization of a large scale parameter estimation problem associated with modeling water flow in a heterogeneous deep vadose zone; (2) the parallelization of a complex simulation-optimization procedure for searching for an optimal groundwater remediation design. PGO is developed as an open source code, and is independent of the computer operating system. It has been tested in a heterogeneous computing environment consisting of Solaris 9, Fedora Core 2 Linux, and Microsoft Windows machines, and is freely available for download from http://grid.scut.edu.cn/PGO/.

THE DETERMINATION OF ANTITRUST LIABILITY IN UNITED STATES v. MICROSOFT: THE EMPIRICAL EVIDENCE THE DEPARTMENT OF JUSTICE USED TO PROVE ITS CASE

This paper considers the empirical evidence used by the Department of Justice in the U.S. v. Microsoft antitrust case to prove that Microsoft engaged in exclusionary (and anticompetitive) actions in the browser market as part of its efforts to maintain its dominance of the personal computer operating system market. This evidence deserves special consideration because the District Court made the unusual decision to rely on the empirical evidence presented by the Department of Justice rather than the empirical evidence presented by Microsoft. This decision was unusual because Microsoft's evidence had a strong presumption of validity as it was based on data that Microsoft collected and used in the ordinary course of its business. Furthermore, no market participants used the Department of Justice-sponsored data in any meaningful way. Although it is impossible to determine with any certainty why the District Court ruled the way it did, I conclude that there were two driving forces in the court's decision. The Department of Justice identified serious flaws in Microsoft's data, making it unreliable for the purposes for which Microsoft was using it in the trial. The Department of Justice was also able to show that no such flaws affected the data it sponsored and indeed, on many points, that data was more consistent with the testimony of Microsoft executives than the data sponsored by Microsoft.

Membrane Computing and Graphical Operating Systems

Membrane Computing and Graphical Operating Systems

Bh_ tomo—a Matlab borehole georadar 2D tomography package

bh_ tomo is an open source borehole georadar data processing and ray-based 2D tomography software package developed at the École Polytechnique of Montréal. bh_ tomo runs under Matlab version 7.0 and above, and is therefore portable between computer operating systems supported by Matlab. To perform the tomographic inversions, bh_ tomo includes an implementation of the classical LSQR algorithm, as well as an implementation of the recent geostatistical inversion scheme developed at the École Polytechnique of Montréal. One important motivation behind the development of bh_ tomo was to ease the data processing sequence necessary to perform tomographic inversion of georadar amplitude data, especially when measured between many adjacent boreholes. The software package relies on a mini database and comprises interactive modules to manage, process and interpret the data.

Will nanotechnology change IT paradigms?

There is a clear imperative to continue the IT revolution, even in the face of limits both from the laws of physics, as well as the challenge of managing complexity. Beyond changing the nature of hardware itself, nanotechnology and the replacement of classical logic gates with devices exploiting quantum mechanics could drive new paradigms for computer operating systems, going beyond Turing/von Neumann which is essentially the basis for all of modern IT.

Conversational semantics sustained by commitments

We propose an operational model that combines message meaning and conversational structure in one comprehensive approach. Our long-term research goal is to lay down principles uniting message meaning and conversational structure while providing an operational foundation that could be implemented in open computer systems. In this paper we explore our advances in one aspect of meaning that in theories of language use is known as "signal meaning", and propose a layered model in which the meaning of messages can be defined according to their fitness to advance the state of joint activities. Messages in our model are defined in terms of social commitments, which have been shown to entice conversational structure.