John Urbanic

High Resolution Forward And Inverse Earthquake Modeling on Terascale Computers

For earthquake simulations to play an important role in the reduction of seismic risk, they must be capable of high resolution and high fidelity. We have developed algorithms and tools for earthquake simulation based on multiresolution hexahedral meshes. We have used this capability to carry out 1 Hz simulations of the 1994 Northridge earthquake in the LA Basin using 100 million grid points. Our wave propagation solver sustains 1.21 teraflop/s for 4 hours on 3000 AlphaServer processors at 80% parallel efficiency. Because of uncertainties in characterizing earthquake source and basin material properties, a critical remaining challenge is to invert for source and material parameter fields for complex 3D basins from records of past earthquakes. Towards this end, we present results for material and source inversion of high-resolution models of basins undergoing antiplane motion using parallel scalable inversion algorithms that overcome many of the difficulties particular to inverse heterogeneous wave propagation problems.

Remote runtime steering of integrated terascale simulation and visualization

We have developed a novel analytic capability for scientists and engineers to obtain insight from ongoing large-scale parallel unstructured mesh simulations running on thousands of processors. The breakthrough is made possible by a new approach that visualizes partial differential equation (PDE) solution data simultaneously while a parallel PDE solver executes. The solution field is pipelined directly to volume rendering, which is computed in parallel using the same processors that solve the PDE equations. Because our approach avoids the bottlenecks associated with transferring and storing large volumes of output data, it offers a promising approach to overcoming the challenges of visualization of petascale simulations. The submitted video demonstrates real-time on-the-fly monitoring, interpreting, and steering from a remote laptop computer of a 1024-processor simulation of the 1994 Northridge earthquake in Southern California.

Real-time terascale implementation of tele-immersion

Tele-immersion is a new medium that enables a user to share a virtual space with remote participants, by creating the illusion that users at geographically dispersed locations reside at the same physical space. A person is immersed in a remote world, whose 3D representation is acquired remotely, then transmitted and displayed in the viewers environment. Tele-immersion is effective only when the three components, computation, transmission, and rendering - all operate in real time . In this paper, we describe the real-time implementation of scene reconstruction on the Terascale Computing System at the Pittsburgh Supercomputing Center.

Creating Effective Online Training Videos from Live Training Event Recordings

Posting video of live training events is frequently requested but can often benefit from planning and minor editing. In this presentation, we will describe how live training events were staged and recorded with an eye toward later reuse, followed by a description of postprocessing tips to prepare the recording for asynchronous training use. Techniques to produce online training videos quickly and cost-effectively will be described. We will then discuss online training video usage data and feedback collection plans, and the application of analytics to understand learner behavior and improve future training materials.

XSEDE OpenACC workshop enables Blue Waters Researchers to Accelerate Key Algorithms

The Blue Waters system at the National Center for Supercomputing Applications (NCSA) is the largest GPU accelerated system in the NSFs portfolio with greater than (>) 4200 Nvidia K20x accelerators and greater than (>) 22500 compute nodes overall. Using the accelerator nodes effectively is paramount to the systems success as they represent approximately 1/7 of system peak performance. As an XSEDE level 2 service provider, the system is also available to education allocations proposed by XSEDE educators and trainers. The training staff working at Pittsburgh Supercomputing Center (PSC) along with their XSEDE and Nvidia partners have offered multiple OpenACC workshops since 2012. The most recent workshop was conducted on Blue Waters hosting the hands-on sessions and it was very successful. As a direct result of working with PSC on these workshop, NCSA researchers have been able to obtain significant speedups on real-world algorithms using OpenACC in the Cray environment. In this work we will look at two key kernel codes (3D FFT kernel, Laplace 2D MPI benchmark) and the path to obtaining the observed performance gains.