Computer Engineering Commons^™

Qos Scalability For Streamed Media Delivery, Charles Krasic, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Applications with real-rate progress requirements, such as mediastreaming systems, are difficult to deploy in shared heterogenous environments such as the Internet. On the Internet, mediastreaming systems must be capable of trading off resource requirements against the quality of the media streams they deliver, in order to match wide-ranging dynamic variations in bandwidth between servers and clients. Since quality requirements tend to be user- and task-specific, mechanisms for capturing quality of service requirements and mapping them to appropriate resource-level adaptation policies are required. In this paper, we describe a general approach for automatically mapping user-level quality of service specifications onto resource …

Fine-Grain Period Adaptation In Soft Real-Time Environments, David Steere, Joshua Gruenberg, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Reservation-based scheduling delivers a proportion of the CPU to jobs over a period of time. In this paper we argue that automatically determining and assigning this period is both possible and useful in general purpose soft real-time environments such as personal computers and information appliances. The goal of period adaptation is to select the period over which a job is guaranteed to receive its portion of the CPU dynamically and automatically. The choice of period represents a trade-off between the amount of jitter observed by the job and the overall efficiency of the system. Secondary effects of period include quantization …

Constructive Induction Machines For Data Mining, Marek Perkowski, Stanislaw Grygiel, Qihong Chen, Dave Mattson

Electrical and Computer Engineering Faculty Publications and Presentations

"Learning Hardware" approach involves creating a computational network based on feedback from the environment (for instance, positive and negative examples from the trainer), and realizing this network in an array of Field Programmable Gate Arrays (FPGAs). Computational networks can be built based on incremental supervised learning (Neural Net training) or global construction (Decision Tree design). Here we advocate the approach to Learning Hardware based on Constructive Induction methods of Machine Learning (ML) using multivalued functions. This is contrasted with the Evolvable Hardware (EHW) approach in which learning/evolution is based on the genetic algorithm only.

Adaptive Resource Management Via Modular Feedback Control, Ashvin Goel, David Steere, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

A key feature of tomorrow’s operating systems and runtime environments is their ability to adapt. Current state of the art uses an ad-hoc approach to building adaptive software, resulting in systems that can be complex, unpredictable and brittle. We advocate a modular and methodical approach for building adaptive system software based on feedback control. The use of feedback allows a system to automatically adapt to dynamically varying environments and loads, and allows the system designer to utilize the substantial body of knowledge in other engineering disciplines for building adaptive systems. We have developed a toolkit called SWiFT that embodies this …

Feedback Based Dynamic Proportion Allocation For Disk I/O, Dan Revel, Dylan Mcnamee, Calton Pu, David Steere, Jonathan Walpole

Computer Science Faculty Publications and Presentations

In this paper we propose to use feedback control to automatically allocate disk bandwidth in order to match the rate of disk I/O to the real-rate needs of applications. We describe a model for adaptive resource management based on measuring the relative progress of stages in a producer-consumer pipeline. We show how to use prefetching to transform a passive disk into an active data producer whose progress can be controlled via feedback. Our progress-based framework allows the integrated control of multiple resources. The resulting system automatically adapts to varying application rates as well as to varying device latencies.

A Feedback-Driven Proportion Allocator For Real-Rate Scheduling, David Steere, Ashvin Goel, Joshua Gruenberg, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

In this paper we propose changing the decades-old practice of allocating CPU to threads based on priority to a scheme based on proportion and period. Our scheme allocates to each thread a percentage of CPU cycles over a period of time, and uses a feedback-based adaptive scheduler to assign automatically both proportion and period. Applications with known requirements, such as isochronous software devices, can bypass the adaptive scheduler by specifying their desired proportion and/or period. As a result, our scheme provides reservations to applications that need them, and the benefits of proportion and period to those that do not. Adaptive …

Synthetic Files: Enabling Low-Latency File I/O For Qos-Adaptive Applications, Dylan Mcnamee, Dan Revel, Calton Pu, David Steere, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Files are a tried and true operating system abstraction. They present a simple byte-stream model of I/O that has proven intuitive for application programmers and efficient for operating system builders. However, current file systems do not provide good support for adaptive continuous media (CM) applications - an increasingly important class of applications that exhibit complex access patterns and are particularly sensitive to variations in I/O performance. To address these problems we propose synthetic files. Synthetic files are specialized views of underlying regular files, and convert complex file access patterns into simple sequential synthetic file access patterns. Synthetic file construction can …

Quality Of Service Semantics For Multimedia Database Systems, Jonathan Walpole, Charles Krasic, Ling Liu, David Maier, Calton Pu, Dylan Mcnamee, David Steere

Computer Science Faculty Publications and Presentations

Quality of service (QoS) support has been a hot research topic in multimedia databases, and multimedia systems in general, for the past several years. However, there remains little consensus on how QoS support should be provided. At the resource-management level, systems designers are still debating the suitability of reservation- based versus adaptive QoS management. The design of higher system layers is less clearly understood, and the specification of QoS requirements in domain-specific terms is still an open research topic. To address these issues, we propose a QoS model for multimedia databases. The model covers the specification of user-level QoS preferences …

Location Independent Names For Nomadic Computers, David Steere, Mark Morrissey, Peter Geib, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Recent advances in the Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP) have enabled a new approach to supporting mobile users: location independent naming. In this approach, machines use the same hostname from any internet location, but use an IP address that corresponds to their current location. We describe a protocol that implements location independent naming for nomadic computers, i.e., machines that do not need transparent mobility. Our protocol allows hosts to move across security domains, uses existing protocols, and preserves existing trust relationships. Therefore, it preserves the performance and security of normal IP for nomadic computers …

Adaptation Space: Surviving Non-Maskable Failures, Crispin Cowan, Lois Delcambre, Anne-Francoise Le Meur, Ling Liu, David Maier, Dylan Mcnamee, Michael Miller, Calton Pu, Perry Wagle, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Some failures cannot be masked by redundancies, because an unanticipated situation occurred, because fault-tolerance measures were not adequate, or because there was a security breach (which is not amenable to replication). Applications that wish to continue to offer some service despite nonmaskable failure must adapt to the loss of resources. When numerous combinations of non-maskable failure modes are considered, the set of possible adaptations becomes complex. This paper presents adaptation spaces, a formalism for navigating among combinations of adaptations. An adaptation space describes a collection of possible adaptations of a software component or system, and provides a uniform way of …

Stackguard: Automatic Adaptive Detection And Prevention Of Buffer-Overflow Attacks, Crispin Cowan, Calton Pu, David Maier, Heather Hinton, Jonathan Walpole, Peat Bakke, Steve Beattie, Aaron Grier, Perry Wagle, Qian Zhang

Computer Science Faculty Publications and Presentations

This paper presents a systematic solution to the persistent problem of buffer overflow attacks. Buffer overflow attacks gained notoriety in 1988 as part of the Morris Worm incident on the Internet. While it is fairly simple to fix individual buffer overflow vulnerabilities, buffer overflow attacks continue to this day. Hundreds of attacks have been discovered, and while most of the obvious vulnerabilities have now been patched, more sophisticated buffer overflow attacks continue to emerge.

We describe StackGuard: a simple compiler technique that virtually eliminates buffer overflow vulnerabilities with only modest performance penalties. Privileged programs that are recompiled with the StackGuard …

Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The emergence of streaming multimedia players provides users with low latency audio and video content over the Internet. Providing high-quality, best-effort, real-time multimedia content requires adaptive delivery schemes that fairly share the available network bandwidth with reliable data protocols such as TCP. This paper proposes a new flow and congestion control scheme, SCP (Streaming Control Protocol) , for real-time streaming of continuous multimedia data across the Internet. The design of SCP arose from several years of experience in building and using adaptive real-time streaming video players. SCP addresses two issues associated with real-time streaming. First, it uses a congestion control …

A Player For Adaptive Mpeg Video Streaming Over The Internet, Jonathan Walpole, Rainer Koster, Shanwei Cen, Crispin Cowan, David Maier, Dylan Mcnamee, Calton Pu, David Steere, Liujin Yu

Computer Science Faculty Publications and Presentations

This paper describes the design and implementation of a real-time, streaming, Internet video and audio player. The player has a number of advanced features including dynamic adaptation to changes in available bandwidth, latency and latency variation; a multi-dimensional media scaling capability driven by user-specified quality of service (QoS) requirements; and support for complex content comprising multiple synchronized video and audio streams. The player was developed as part of the QUASAR t project at Oregon Graduate Institute, is freely available, and serves as a testbed for research in adaptive resource management and QoS control.

Dynamic Load Distribution In Mist, K. Al-Saqabi, R. M. Prouty, Dylan Mcnamee, Steve Otto, Jonathan Walpole

Computer Science Faculty Publications and Presentations

This paper presents an algorithm for scheduling parallel applications in large-scale, multiuser, heterogeneous distributed systems. The approach is primarily targeted at systems that harvest idle cycles in general-purpose workstation networks, but is also applicable to clustered computer systems and massively parallel processors. The algorithm handles unequal processor capacities, multiple architecture types and dynamic variations in the number of processes and available processors. Scheduling decisions are driven by the desire to minimize turnaround time while maintaining fairness among competing applications. For efficiency, the virtual processors (VPs) of each application are gang scheduled on some subset of the available physical processors.

A Toolkit For Specializing Production Operating System Code, Crispin Cowan, Dylan Mcnamee, Andrew P. Black, Calton Pu, Jonathan Walpole, Charles Krasic, Perry Wagle, Qian Zhang

Computer Science Faculty Publications and Presentations

Specialization has been recognized as a powerful technique for optimizing operating systems. However, specialization has not been broadly applied beyond the research community because the current techniques, based on manual specialization, are time-consuming and error-prone. This paper describes a specialization toolkit that should help broaden the applicability of specializing operating systems by assisting in the automatic generation of specialized code, and {\em guarding} the specialized code to ensure the specialized system continues to be correct. We demonstrate the effectiveness of the toolkit by describing experiences we have had applying it in real, production environments. We report on our experiences with …

Predictable File Access Latency For Multimedia, Dan Revel, Crispin Cowan, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Multimedia applications are sensitive to I/O latency and jitter when accessing data in secondary storage. Transparent adaptive prefetching (TAP) uses software feedback to provide multimedia applications with file system quality of service (QoS) guarantees. We are investigating how QoS requirements can be communicated and how they can be met by adaptive resource management. A preliminary test of adaptive prefetching is presented.

A Simplified Approach To Reduce Blocking And Ringing Artifacts In Transform-Coded Images, Jianping Hu

Dissertations and Theses

Presently Block-based Discrete Cosine Transform (BDCT) image coding techniques are widely used in image and video compression applications such as JPEG and MPEG. At a moderate bit rate, BDCT is usually a quite satisfactory solution to most of practical coding applications. However, for high rate compression it produces noticeable blocking and ringing artifacts in the decompressed image. It has been an active research area for a decade for reducing these artifacts. In this thesis, a novel post-processing algorithm is proposed to remove the blocking and ringing artifacts at low bit rate. It is non-iterative and uses both spatial and transform …

Physical Media Independence: System Support For Dynamically Available Network Interfaces, Jon Inouye, Jim Binkley, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Advances in hardware technology has fueled the proliferation of dynamically configurable network interface cards. This empowers mobile laptop users to select the most appropriate interface for their current environment. Unfortunately, the majority of system software remains "customized" for a particular network configuration, and assumes many network characteristics remain invariant over the runtime of the software. Physical Media Independence (PMI) is the concept of making assumptions about a particular device explicit, detecting events which invalidate these assumptions, and recovering once events are detected. This paper presents a model supporting PMI. Based on device availablilty, the model identifies implicit device-related assumptions made …

A Specialization Toolkit To Increase The Diversity Of Operating Systems, Calton Pu, Andrew P. Black, Crispin Cowan, Jonathan Walpole, Charles Consel

Computer Science Faculty Publications and Presentations

Virus and worm attacks that exploit system implementation details can be countered with a diversified set of implementations. Furthermore, immune systems show that attacks from previously unknown organisms require effective dynamic response. In the Synthetix project, we have been developing a specialization toolkit to improve the performance of operating system kernels. The toolkit helps programmers generate and manage diverse specialized implementations of software modules. The Tempo-C specializer tool generates different versions for both compile-time and run-time specialization. We are now adapting the toolkit to improve operating system survivability against implementations attacks.

Analysis And Optimization Of A Banyan Based Atm Switch By Simulations, Syed Sohel Hussain

Dissertations and Theses

Asynchronous Transfer Mode (ATM) is proposed technology to create a broadband (high speed) packet switching network capable of transporting wide variety of services including voice, video and data in an integrated manner. The main concern in designing the switching fabrics used in this technology are speed, throughput, delay and variance of delay. We analyze the performance by simulations of ATM switch based on Banyan network in the uniform traffic condition.

We compare the analytical results obtained from three-state model Yan and Jenq to the simulation results. Based on observation of simulation results, we propose non-blocking first stage (NBFS) to increase …

Multimedia Applications Require Adaptive Cpu Scheduling, Veronica Baiceanu, Crispin Cowan, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

CPU scheduling and admission testing for multimedia applications have been extensively studied, and various solutions have been proposed using assorted simplifying assumptions. However, we believe that the complexity and dynamic behavior of multimedia applications and systems make static solutions hard to apply in real-world situations. We are analyzing the difficulties that arise when applying the rate-monotonic (RM) scheduling algorithm and the corresponding admission tests for CPU management, in the context of real multimedia applications running on real systems. RM requires statically predictable, periodic workloads, and while multimedia applications appear to be periodic, in practice they exhibit numerous variabilities in workload. …

Adaptive Methods For Distributed Video Presentation, Crispin Cowan, Shanwei Cen, Jonathan Walpole, Carlton Pu

Computer Science Faculty Publications and Presentations

This paper describes problems and solutions for delivering real-time, multi-media presentations across the Internet. A key characteristic of presentations of continuous media datatypes, such as digital video and audio, is their need for predictable real-time data delivery. For example, an NTSC quality video presentation requires video frames to be displayed every 1/30th of a second. Variations in this display rate can be observable as stalls or glitches in the video stream and reduce the quality of the presentation [6]. Delivering such presentations across the Internet is difficult because highly variable band- width and latency make it difficult to predict the …

Customizable Operating Systems, Jonathan Walpole, Crispin Cowan, Andrew P. Black, Jon Inouye, Calton Pu, Shanwei Cen

Computer Science Faculty Publications and Presentations

A customizable operating system is one that can adapt to improve its functionality or performance. The need for customizable and application-specific operating systems has been recognized for many years, but they have yet to appear in the commercial market. This paper explores the notion of operating system customizability and examines the limits of existing approaches. The paper begins by surveying system structuring approaches for the safe and efficient execution of customizable operating systems. Then it discusses the burden that existing approaches impose on application software, and explores techniques for reducing this burden. Finally, support for customizability in the Synthetix project …

Device And Physical Data Independence For Multimedia Presentations, Richard Staehli, Jonathan Walpole, David Maier

Computer Science Faculty Publications and Presentations

Multimedia computing promises access to any type of visual or aural medium on the desktop. But in this networked future, will every type of media be accessible from every terminal device? Current multimedia standards do not allow content that is authored for high-bandwidth workstations to scale down for low-bandwidth applications. The problem is that application requests are commonly interpreted as requests for the highest possible quality and resource overloads are handled by ad hoc methods. We can begin to solve this problem by specifying Quality of Service (QOS) requirements based on functionality rather than on content encoding and device capabilities.

Quality Of Service Specification For Multimedia Presentations, Richard Staehli, Jonathan Walpole, David Maier

Computer Science Faculty Publications and Presentations

The bandwidth limitations of multimedia systems force tradeoffs between presentation data fidelity and real-time performance. For example, digital video is commonly encoded with lossy compression to reduce bandwidth and frames may be skipped during playback to maintain synchronization. These tradeoffs depend on device performance and physical data representations that are hidden by a database system. If a multimedia database is to support digital video and other continuous media data types, we argue that the database should provide a Quality of Service (QOS) interface to allow application control of presentation timing and information loss tradeoffs.

This paper proposes a data model …

Device And Physical Data Independence For Multimedia Presentations, Richard Staehli, Jonathan Walpole, David Maier

Computer Science Faculty Publications and Presentations

Multimedia computing promises access to any type of visual or aural medium on the desktop. But in this networked future, will every type of media be accessible from every terminal device? Current multimedia standards do not allow content that is authored for high-bandwidth workstations to scale down for low-bandwidth applications. The problem is that application requests are commonly interpreted as requests for the highest possible quality and resource overloads are handled by ad hoc methods. We can begin to solve this problem by specifying Quality of Service (QOS) requirements based on functionality rather than on content encoding and device capabilities.

Mpvm: A Migration Transparent Version Of Pvm, Jeremy Casas, Dan Clark, Ravi Konuru, Steve Otto, Robert Prouty, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Parallel Virtual Machine (PVM) is a widely-used software system that allows a heterogeneous set of parallel and serial UNIX-based computers to be programmed as a single message-passing parallel machine, In this paper, an extension to PVM to support dynamic process migration is presented. Support for migration is important in general-purpose workstation environments since it allows parallel computations to co-exist with other applications, using idle-cycles as they become available and off-loading from workstations when they are no longer free. A description and evaluation of the design and implementation of the prototype Migratable PVM system is presented together with some performance results.

Evolution Of Emergent Computation, James P. Crutchfield, Melanie Mitchell

Computer Science Faculty Publications and Presentations

A simple evolutionary process can discover sophisticated methods for emergent information processing in decentralized spatially-extended systems. The mechanisms underlying the resulting emergent computation are explicated by a novel technique for analyzing particle-based logic embedded in pattern-forming systems. Understanding how globally-coordinated computation can emerge in evolution is relevant both for the scientific understanding of natural information processing and for engineering new forms of parallel computing systems.

Scheduling Of Parallel Jobs On Dynamic, Heterogenous Networks, Dan Clark, Jeremy Casas, Steve Otto, Robert Prouty, Jonathan Walpole

Computer Science Faculty Publications and Presentations

In using a shared network of workstations for parallel processing, it is not only important to consider heterogeneity and differences in processing power between the workstations but also the dynamics of the system as a whole. In such a computing environment where the use of resources vary as other applications consume and release resources, intelligent scheduling of the parallel jobs onto the available resources is essential to maximize resource utilization. Despite this realization, however, there are few systems available that provide an infrastructure for the easy development and testing of these intelligent schedulers. In this paper, an infrastructure is presented …

Optimizing Object Invocation Using Optimistic Incremental Specialization, Jon Inouye, Andrew P. Black, Charles Consel, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

To make object invocation efficient, it is important to minimize overhead. In general, overhead is incurred in order to maintain transparency; with the advent of mobile computer systems, persistence, increasing security and privacy concerns, transparency becomes more expensive and overhead is increasing. Invocation mechanisms maintain transparency by finding objects, choosing communication media, performing data translation into common formats (e.g., XDR), marshalling arguments, encrypting confidential data, etc. Performing all of these operations on every invocation would lead to unacceptable performance, so designers often avoid operations by specializing object invocation for more restricted environments. For example, the Emerald compiler performs several optimizations …