The National Energy Research Scientific Computing Center (NERSC) is collaborating with supercomputing vendors Intel and Cray to prepare for Cori, the Cray XC supercomputer scheduled to be deployed at NERSC in 2016.

Named in honor of American biochemist Gerty Cori, the next-generation supercomputer will have a sustained performance that is at least ten times that of the NERSC-6 “Hopper” system on a set of representative benchmarks, and will employ the next-generation Intel Xeon Phi Knights Landing (KNL) processors.

Although exascale systems could be built with today’s technology through brute-force techniques, current codes would lack the ability to take full advantage of such systems. As the post-petascale era unfolds, creating useful applications is increasingly difficult and thus requires targeted programs.

Despite the crucial role of application development, all too often it’s the system that gets the bulk of the attention and funding. The NERSC Exascale Science Applications Program (NESAP) was established to address this gap by ensuring that the highly diverse workloads of the DOE science community continue to be supported as over 5,000 users make the transition to Cori.

Scheduled to last through the acceptance of the Cori system, NESAP connects 20 application teams with resources at NERSC, Cray, and Intel. Teams get access to prototype Knights Landing processor hardware (expected in late 2015), as well as early access and significant time on the full Cori system (expected delivery mid-2016). The NESAP program also includes broad-based user training and application kernel deep dives with Cray and Intel specialists.

The Intel Knights Landing processor that will be housed within the Cray XC environment features 60 cores per node with multiple hardware threads on each core. The processor also introduces several technological advances, including higher intra-node parallelism; high-bandwidth, on-package memory; and longer hardware vector lengths. The advantage of a self-hosted architecture means that data movement on and off of a coprocessor is spared.

“We are excited about launching NESAP in partnership with Cray and Intel to help transition our broad user base to energy-efficient architectures,” said Sudip Dosanjh, director of NERSC, the primary HPC facility for the DOE’s Office of Science. “We expect to see many aspects of Cori in an exascale computer, including dramatically more concurrency and on-package memory. The response from our users has been overwhelming – they recognize that Cori will allow them to do science that can’t be done on today’s supercomputers.”

The 20 NESAP teams will be focused on how to best leverage the new architecture’s various features. The main challenge faced by application developers is finding more ways to exploit the added parallelism enabled by the transition to manycore. As systems get closer to the exascale mark, the entire undertaking gets more difficult. NERSC and Cray have also established a joint Center of Excellence to help users port and optimize target applications that will run on Cori.

Harvey Wasserman, HPC consultant at NERSC and NESAP post-doc lead, explains that the goal of NESAP is that “once Cori arrives, we have users who can immediately take advantage of this advanced architecture to produce trailblazing science for the DOE mission.”

NERSC evaluated submissions for the code optimization program based on the following criteria:

• An application’s computing usage within the DOE Office of Science
• Representation among all 6 Offices of Science
• Ability for application to produce scientific advancements
• Ability for code development and optimizations to be transferred to the broader community through libraries, algorithms, kernels or community codes
• Resources available from the application team to match NERSC/Vendor resources

A list of the 20 applications that were selected will be announced soon.