How do we build platforms that take graphics applications from one user on a single GPU to 10,000 machines and one million users in the cloud? Even though computer graphics has always been at the vanguard of parallel computing, there has been little success using modern cloud-based computing resources to improve interactive experiences. In this project we asked the question, how could we leverage the massive storage and batch processing capabilities of the cloud to generate new forms of interactive worlds -- and we took a "precompute everything" approach to doing so. Since one cannot precompute everything about an complex interactive world, the challenge is to determine what is most important to precompute, so these parts can be presented to the user with the highest-quality graphics. We find that by recording statistics of users playing a game, we can build a model of user behavior, and then concentrate large-scale, cloud-based precomputation of graphics and physics around the states that users are most likely to encounter. The result is a self-refining game whose dynamics improve with play, ultimately providing realistically rendered, rich fluid dynamics in real time on a mobile device. For more detail, see our work applied these ideas to cloth simulation and fluid simulation.

GPUs will soon have the compute horsepower to render scenes containing cinematic-quality surfaces in real-time. Unfortunately, if they render these subpixel polygons (micropolygons) using the same techniques as they do for large triangles today, GPUs will perform extremely inefficiently. Instead of trying to parallelize Pixar's Reyes micropolygon rendering system, we're taking a hard look at how the existing Direct3D 11 rendering pipeline, and GPU hardware implementations, must evolve to render micropolygon workloads efficiently in a high-throughput system. Changes to software interfaces, algorithms, and HW design are fair game! Slides describing what we've learned can be found in this SIGGRAPH course talk or in my dissertation: Evolving the Real-Time Graphics Pipeline for Micropolygon Rendering.

There are two ways to think about GRAMPS. Graphics folks should think of GRAMPS as a system for building custom graphics pipelines. We simply gave up on adding more and more configurable knobs to existing pipelines like OpenGL/Direct3D and instead allow the programmer to programmatically define a custom pipeline with an arbitrary number of stages connected by queues. To non-graphics folks, GRAMPS is a stream programming system that embraces heterogeneity in underlying architecture and anticipates streaming workloads that exhibit both regular and irregular (dynamic) behavior. The GRAMPS runtime dynamically schedules GRAMPS programs onto architectures containing a mixture of compute-optimized cores, generic CPU cores, and fixed-function processing units.

Sequoia is a hierarchical stream programming language that arose from the observation that expressing locality, not parallelism is the most important responsibility of parallel application programmers in scientific/numerical domains. Sequoia presents a parallel machine as an abstract hierarchy of memories and gives the programmer explicit control over data locality and communication through this hierarchy using first-class language constructs (basically, Sequoia supports nested kernels and streams of streams). Sequoia programs have run on a variety of exposed-communication architectures such as clusters, the CELL processor, GPUs, and even supercomputing clusters at Los Alamos. The best way to learn about Sequoia is to read our SC06 paper.

I helped out with the BrookGPU (abstracting the GPU as a stream processor for numerical computing) and Merrimac Streaming Supercomputer projects.