Physical Sciences and Mathematics Commons^™

Transportable Agents, Keith D. Kotay, David Kotz

Dartmouth Scholarship

As network information resources grow in size, it is often most efficient to process queries and updates at the site where the data is located. This processing can be accomplished by using a traditional client-server network interface, which constrains the client to the set of queries supported by the server, or requires the server to send all data to the client for processing. The former is inflexible; the latter is inefficient. Transportable agents, which support the movement of the client computation to the location of the remote resource, have the potential to be more flexible and more efficient. Transportable agents …

Multimedia Authoring, Development Environments, And Digital Video Editing, Fillia Makedon, James W. Matthews, Charles B. Owen, Samuel A. Rebelsky

Dartmouth Scholarship

Multimedia systems integrate text, audio, video, graphics, and other media and allow them to be utilized in a combined and interactive manner. Using this exciting and rapidly developing technology, multimedia applications can provide extensive benefits in a variety of arenas, including research, education, medicine, and commerce. While there are many commercial multimedia development packages, the easy and fast creation of a useful, full-featured multimedia document is not yet a straightforward task.

This paper addresses issues in the development of multimedia documents, ranging from user-interface tools that manipulate multimedia documents to multimedia communication technologies such as compression, digital video editing and …

Disk-Directed I/O For Mimd Multiprocessors, David Kotz

Dartmouth Scholarship

Many scientific applications that run on today's multiprocessors are bottlenecked by their file I/O needs. Even if the multiprocessor is configured with sufficient I/O hardware, the file-system software often fails to provide the available bandwidth to the application. Although libraries and improved file-system interfaces can make a significant improvement, we believe that fundamental changes are needed in the file-server software. We propose a new technique, \em disk-directed I/O, that flips the usual relationship between server and client to allow the disks (actually, disk servers) to determine the flow of data for maximum performance. Our simulations show that tremendous performance gains …

Characterizing Parallel File-Access Patterns On A Large-Scale Multiprocessor, Apratim Purakayastha, Carla Schlatter Ellis, David Kotz, Nils Nieuwejaar, Michael Best

Dartmouth Scholarship

Rapid increases in the computational speeds of multiprocessors have not been matched by corresponding performance enhancements in the I/O subsystem. To satisfy the large and growing I/O requirements of some parallel scientific applications, we need parallel file systems that can provide high-bandwidth and high-volume data transfer between the I/O subsystem and thousands of processors. \par Design of such high-performance parallel file systems depends on a thorough grasp of the expected workload. So far there have been no comprehensive usage studies of multiprocessor file systems. Our CHARISMA project intends to fill this void. The first results from our study involve an …

Improved Algorithms For Bipartite Network Flow, Ravindra K. Ahuja, James B. B. Orlin, Clifford Stein, Robert E. Tarjan

Dartmouth Scholarship

In this paper, network flow algorithms for bipartite networks are studied. A network G = (V,E) is called bipartite if its vertex set V can be partitioned into two subsets V_1 and V_2 such that all edges have one endpoint in V_1 and the other in $V_2 $. Let $n = |V|, n_1 = |V_1 | , n_2 = |V_2 |, m = |E| and assume without loss of generality that n_1 \leqslant n_2. A bipartite network is called unbalanced if n_1 \ll n_2 $ and balanced otherwise. (This notion is necessarily imprecise.) It is shown that several maximum flow …

Teaching Parallel Computing To Freshmen, Donald Johnson, David Kotz, Fillia Makedon

Dartmouth Scholarship

Parallelism is the future of computing and computer science and should therefore be at the heart of the CS curriculum. Instead of continuing along the evolutionary path by introducing parallel computation “top down” (first in special junior-senior level courses), we are taking a radical approach and introducing parallelism at the earliest possible stages of instruction. Specifically, we are developing a completely new freshman-level course on data structures that integrates parallel computation naturally, and retains the emphasis on laboratory instruction. This will help to steer our curriculum as expeditiously as possible toward parallel computing.

Our approach is novel in three distinct …

The Expected Lifetime Of “Single-Address-Space” Operating Systems, David Kotz, Preston Crow

Dartmouth Scholarship

Trends toward shared-memory programming paradigms, large (64-bit) address spaces, and memory-mapped files have led some to propose the use of a single virtual-address space, shared by all processes and processors. Typical proposals require the single address space to contain all process-private data, shared data, and stored files. To simplify management of an address space where stale pointers make it difficult to re-use addresses, some have claimed that a 64-bit address space is sufficiently large that there is no need to ever re-use addresses. Unfortunately, there has been no data to either support or refute these claims, or to aid in …

Disk-Directed I/O For Mimd Multiprocessors, David Kotz

Dartmouth Scholarship

Many scientific applications that run on today's multiprocessors are bottlenecked by their file I/O needs. Even if the multiprocessor is configured with sufficient I/O hardware, the file-system software often fails to provide the available bandwidth to the application. Although libraries and improved file-system interfaces can make a significant improvement, we believe that fundamental changes are needed in the file-server software. We propose a new technique, \em disk-directed I/O, that flips the usual relationship between server and client to allow the disks (actually, disk servers) to determine the flow of data for maximum performance. Our simulations show that tremendous performance gains …

Issues And Obstacles With Multimedia Authoring, Fillia Makedon, Samuel A. Rebelsky, Matthew Cheyney, Charles Owen, Peter Gloor

Dartmouth Scholarship

Unlike traditional authoring, multimedia authoring involves making hard choices, forecasting technological evolution and adapting to software and hardware technology changes. It is, perhaps, an unstable field of endeavor for an academic to be in. Yet, it is important that academics are, in fact, part of this process. This paper discusses some of the common threads shared by three dissimilar cases of multimedia authoring which we have experimented with, that of multimedia conference proceedings, multimedia courseware development and multimedia information kiosks. We consider these applications from an academic point of view and review the benefits and pitfalls of academic development while …

Generalized Ffts - A Survey Of Some Recent Results, David K. Maslen, Daniel N. Rockmore

Dartmouth Scholarship

In this paper we survey some recent work directed towards generalizing the fast Fourier transform (FFT). We work primarily from the point of view of group representation theory. In this setting the classical FFT can be viewed as a family of efficient algorithms for computing the Fourier transform of either a function defined on a finite abelian group, or a bandlimited function on a compact abelian group. We discuss generalizations of the FFT to arbitrary finite groups and compact Lie groups.