As the distribution of the video over the Internet becomes main- stream and its consumption moves from the computer to the TV screen, user expectation for high quality is constantly increasing. In this context, it is crucial for content providers to understand if and how video quality affects user engagement and how to best invest their resources to… (More)
Video traffic already represents a significant fraction of today's traffic and is projected to exceed 90% in the next five years. In parallel, user expectations for a high quality viewing experience (e.g., low startup delays, low buffering, and high bitrates) are continuously increasing. Unlike traditional workloads that either require low latency (e.g.,… (More)
We present Oblio, a sparse direct solver library running in both serial an parallel environments. The code is written in C++ using object-oriented techniques, with the exception of few computationally intensive k ernels that are written in Fortran 77. In this paper we explain what motivated the project, discuss design issues and report recent results .
A parallel, fully coupled, nonlinearly implicit Newton-Krylov-Schwarz algorithm is proposed for the numerical simulation of a magnetic reconnection problem described by a system of resistive Hall magnetohydrodynamics equations in slab symmetry. A key component of the algorithm is a restricted additive Schwarz preconditioner defined for problems with doubly… (More)
We discuss the design and implementation of new highly-scalable distributed-memory parallel algorithms for two prototypical graph problems, edge-weighted matching and distance-1 vertex coloring. Graph algorithms in general have low concurrency, poor data locality, and high ratio of data access to computation costs, making it challenging to achieve… (More)
We consider two problems related to I/O: First, find the minimum primary memory size required to factor a sparse, symmetric matrix when permitted to read and write the data exactly once. Second, find the minimum data traffic between core and external memory when permitted to read and write the data many times. These problems are likely to be intractable in… (More)
We discuss the object-oriented design of a software package for solving sparse, symmetric systems of equations (positive definite and indefinite) by direct methods. At the highest layers, we decouple data structure classes from algorithmic classes for flexibility. We describe the important structural and algorithmic classes in our design, and discuss the… (More)