Now showing items 206-225 of 245

    • Taking TrackBack Back (from Spam) 

      Gerecht, Paul; McDonald, Rob; Sandler, Dan; Wallach, Dan S. (2006-05-19)
      The TrackBack protocol, conceived as a way to automatically link together web sites which reference one another, has become a new vector for spammers wishing to divert web surfers to their sites. A site which supports TrackBack allows any entity to inject arbitrary HTML code, plus the URL of the sender, into its pages; an attacker need only follow ...
    • TCP Implementation Enhancements for Improving Webserver Performance 

      Aron, Mohit; Druschel, Peter (1999-07-06)
      This paper studies the performance of BSD-based TCP implementations in Web servers. We find that lack of scalability with respect to high TCP connection rates reduces the throughput of Web servers by up to 25% and imposes a memory overhead of up to 32 MB on the kernel. We also find that insufficient accuracy in TCP's timers results in overly conservative ...
    • TCP: Improving Startup Dynamics by Adaptive Timers and Congestion Control 

      Aron, Mohit; Druschel, Peter (1998-06-03)
      This paper studies the startup dynamics of TCP on both high as well as low bandwidth-delay network paths and proposes a set of enhancements that improve both the latency as well as throughput of relatively short TCP transfers. Numerous studies have shown that the timer and congestion control mechanisms in TCP can have a limiting effect on performance ...
    • Techniques for Efficient Cell-Level ATM Simulations 

      Aron, Mohit; Brakmo, Lawrence (2000-02)
      This paper investigates the efficiency of a network simulator in simulating ATM networks with UBR service and compares it to the the efficiency of simulating conventional packet networks. A network simulator can be highly inefficient for cell-level ATM simulations as compared to analogous packet network simulations. We motivate and describe three ...
    • Telescoping MATLAB for DSP Applications 

      Chauhan, Arun (2003-12-05)
      This dissertation designs and implements a prototype MATLAB compiler for Digital Signal Processing (DSP) libraries, based on a novel approach called telescoping languages for compiling high-level languages. The thesis of this work is that it is possible to effectively and efficiently compile DSP libraries written in MATLAB using the telescoping ...
    • Termination in Language-Based Systems 

      Clements, John; Rudys, Algis; Wallach, Dan S. (2000-08-08)
      Language runtime systems are increasingly being embedded in systems to support runtime extensibility via mobile code. Such systems raise a number of concerns when the code running in such systems is potentially buggy or untrusted. While sophisticated access controls have been designed for mobile code and are shipping as part of commercial systems ...
    • The Block Structure of Three Dixon Resultants and Their Accompanying Transformation Matrices 

      Chionh, Eng-Wee; Goldman, Ronald; Zhang, Ming (1999-06-16)
      Dixon [1908] introduces three distinct determinant formulations for the resultant of three bivariate polynomials of bidegree (m,n) . The first technique applies Sylvester's dialytic method to construct the resultant as the determinant of a matrix of order 6mn . The second approach uses Cayley's determinant device to form a more compact representation ...
    • The Concurrent Collections Programming Model 

      Budimlić, Zoran; Burke, Michael G.; Cavé, Vincent; Knobe, Kathleen; Lowney, Geoff; (2010-01-04)
      We introduce the Concurrent Collections (CnC) programming model. In this model, programs are written in terms of high-level operations. These operations are partially ordered according to only their semantic constraints. These partial orderings correspond to data dependences and control dependences. The role of the domain expert, whose interest and ...
    • The Concurrent Collections Programming Model 

      Burke, Michael G.; Knobe, Kathleen; Newton, Ryan; Sarkar, Vivek (2010-12-16)
      Parallel computing has become firmly established since the 1980’s as the primary means of achieving high performance from supercomputers. 1 Concurrent Collections (CnC) was developed to address the need for making parallel programming accessible to non-professional programmers. One approach that has historically addressed this problem is the creation ...
    • The Effect of Deceptive Idleness on Disk Schedulers 

      Druschel, Peter; Iyer, Sitaram (2001-06-19)
      Disk schedulers in operating systems are generally work-conserving; they schedule a request immediately after the previous request has finished. Such schedulers need multiple outstanding requests to make good decisions. Unfortunately, many applications issue synchronous, almost-continuous streams of read requests. This forces the scheduler into making ...
    • The Formal Relationship between Direct and Continuation-Passing Style Optimizing Compilers: A Synthesis of Two Paradigms 

      Sabry, Amr A. (1994-08)
      Compilers for higher-order programming languages like Scheme, ML, and Lisp can be broadly characterized as either “direct compilers” or "continuation-passing style (CPS) compilers", depending on their main intermediate representation. Our central result is a precise correspondence between the two compilation strategies. Starting from the theoretical ...
    • The List Update ProblemImproved Bounds for the Counter Scheme 

      Hofri, Micha; Shachnai, Hadas (1998-02-02)
      We consider the problem of dynamic reorganization of a linear list, where requests for the elements are generated randomly with fixed, unknown probabilities. The objective is to obtain the smallest expected cost per access. It has been shown, that when no a-priori information is given on the reference probabilities, the Counter Scheme (CS) provides ...
    • The Maximum of a Random Walk and Its Application to Rectangle Packing 

      Coffman, Edward G.; Flajolet, Philippe; Hofri, Micha; Leopold, Flatto (1997-07-28)
      Let S0,...,Sn be a symmetric random walk that starts at the origin (S0 = 0), and takes steps uniformly distributed on [-1,+1]. We study the large-n behavior of the expected maximum excursion and prove the estimate$$ \exd \max_{0 \leq k \leq n} S_k = \sqrt{\frac{2n}{3\pi}} c +\frac{1}{5}\sqrt{\frac{2}{3\pi}} n^{-1/2} + O(n^{-3/2}), where c = 0.297952... ...
    • The Platform-Aware Compilation Environment: Preliminary Design Document 

      Cooper, Keith D.; Mellor-Crummey, John; Merényi, Erzsébet; Sadayappan, P.; Sarkar, Vivek; (2010-09-15)
      The Platform-Aware Compilation Environment (PACE) is an ambitious attempt to construct a portable compiler that produces code capable of achieving high levels of performance on new architectures. The key strategies in PACE are the design and development of an optimizer and runtime system that are parameterized by system characteristics, the automatic ...
    • The Platform-Aware Compilation Environment: Status and Future Directions 

      Cooper, Keith D.; Khan, Rishi; Lele, Sanjiva; Mellor-Crummey, John; Merényi, Erzsébet; (2012-06-13)
      The Platform-Aware Compilation Environment (PACE) is an ambitious attempt to construct a portable compiler that produces code capable of achieving high levels of performance on new architectures. The key strategies in PACE are the design and development of an optimizer and runtime system that are parameterized by system characteristics, the automatic ...
    • The Preliminary Design and Implementation of the Maestro Network Control Platform 

      Cai, Zheng; Cox, Alan L.; Dinu, Florin; Ng, T. S. Eugene; Zheng, Jie (2008-10-01)
      Network operation is inherently complex because it consists of many functions such as routing, firewalling, VPN provisioning, traffic load-balancing, network maintenance, etc. To cope with this, network designers have created modular components to handle each function. Un fortunately, in reality, unavoidable dependencies exist between some of the ...
    • The Semantics of Futures 

      Felleisen, Matthias; Flanagan, Cormac (1994-10)
      The future annotation introduced by MultiLisp provides a simple method for taming the implicit parallelism of functional programs. Prior research on futures has concentrated on implementation and design issues, and has largely ignored the development of a semantic characterization of futures. This paper presents four operational semantics for an ...
    • The Task Motion Kit 

      Chaudhuri, Swarat; Dantam, Neil T.; Kavraki, Lydia E. (2016-10-31)
      Expanding the capabilities of robots to achieve complex objectives in new environments requires novel reasoning systems. Everyday tasks in the physical world, such as the table setting in Fig. 1, couple discrete decisions about objects and actions with geometric decisions about collision free motion. Robotics has traditionally treated these issues—task ...
    • Three Approaches to Building Curves and Surfaces in Computer Aided Geometric Design 

      Habib, Ayman W. (1997-05)
      Modeling free-form curves and surfaces is one of the fundamental problems in computer aided geometric design. To solve this problem, several modeling techniques have been proposed. Three of these techniques, are investigated. The unifying theme of these three techniques is the use and the control of geometric continuity. The first technique deals ...
    • Tools for Application-Oriented Performance Tuning 

      Fowler, Robert; Mellor-Crummey, John; Whalley, David (2001-03-14)
      Application performance tuning is a complex process that requires assembling various types of information and correlating it with source code to pinpoint the causes of performance bottlenecks. Existing performance tools don't adequately support this process in one or more dimensions. We discuss some of the critical utility and usability issues for ...