Doug James

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The Lustre file system provides high aggregated I/O bandwidth and is in widespread use throughout the HPC community. Here we report on work (1) developing a model for understanding collective parallel MPI write operations on Lustre, and (2) producing a library that optimizes parallel write performance in a user-friendly way. We note that a system's default(More)
This work enhances our understanding of individual users' software needs, then leverages that understanding to help stakeholders conduct business in a more efficient, effective, and systematic way. The product, XALT, builds on work that is already improving the user experience and enhancing support programs for thousands of users on twelve supercomputers(More)
This is the final report on reproducibility@xsede, a one-day workshop held in conjunction with XSEDE14, the annual conference of the Extreme Science and Engineering Discovery Environment (XSEDE). The workshop's discussion-oriented agenda focused on reproducibility in large-scale computational research. Two important themes capture the spirit of the workshop(More)
XALT is a tracking tool that collects accurate, detailed, and continuous job-level and link-time data. XALT stores that data in a database and ensures that all the data collection is transparent to the users. XALT tracks libraries and object files linked by the application. A recent feature improvement in XALT enable it to also track external subroutines(More)
XALT collects accurate, detailed, and continuous job-level and link-time data and stores that data in a database; all the data collection is transparent to the users. The data stored can be mined to generate a picture of the compilers, libraries, and other software that users need to run their jobs successfully, highlighting the products that researchers(More)
Those participating in HUST '15 appreciate the potential value of high quality tools and technologies intended to enhance the user experience on large-scale computers. Given the changing landscape of large-scale computing, they likely also feel a renewed sense of urgency associated with the emerging needs of an increasingly diverse user base. Do user(More)
The simulation of crowds of virtual characters is needed for applications such as films, games, and virtual reality environments. These simulations are difficult due to the large number of characters to be simulated and the requirement for synthesizing realistic human-like motion efficiently. This thesis focuses on two problems: how to search through and(More)
The problem of finding sets of points that conform to a given underlying spatial model is a conceptually simple, but potentially expensive, task that arises in a variety of domains. The goal is simply to find occurrences of known types of spatial structure in the data. However, as we begin to examine large, dense, and noisy data sets the cost of finding(More)
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