Early Science

Supercomputing is nearing the end of one era and approaching the next. We reached the petascale by combining hundreds of thousand of central processing units—the same type used to power home computers. We will reach the exascale by accelerating the system with graphics processing units, developed originally to improve graphics rendering for computer displays.

The first big step along the way is Titan, a system that will combine CPUs and GPUs to reach up to 20 petaflops, or 20,000 trillion calculations a second.

Making the most of Titan will be no small feat. In 2009 the OLCF began compiling a list of candidate applications that were to be the vanguards of Titan—the first codes that would be adapted to take full advantage of Titan’s mixed architecture. This list was gleaned from research done for the 2009 OLCF report “Preparing for Exascale: OLCF Application Requirements and Strategy” as well as from responses from current and former awardees of INCITE (a Department of Energy-funded program that allocates nearly 60 percent of the available time on the leadership-class system at ORNL). Initially 50 applications were considered, but this list was eventually pared down to a set of six critical codes from various domain sciences: