Aitken Expansion Clocks More than 10,000 Hours in First Three Months
When NASA Advanced Supercomputing (NAS) engineers at NASA Ames Research Center brought the Aitken supercomputer’s expansion into production in March of this year, the update more than tripled the system’s production capability—representing the largest single addition of computing power in the history of the NAS facility.
The eight compute racks (and one cooling rack) installed in November 2020 comprise 1,024 nodes, each with two AMD 7742 EPYC “Rome” 64-core processors, adding 131,072 cores to Aitken—more cores than are contained in the entire Electra supercomputer. The expansion increased Aitken’s performance by 143.3%, for a total of 5.79 petaflops (quadrillion floating-point operations per second) as measured on the LINPACK benchmark. Combined with the system’s original 1,152 Intel Xeon Gold 6248 “Cascade Lake” nodes, the new Rome nodes bring Aitken’s total theoretical peak performance to 8.41 petaflops.
These numbers translate into significantly increased computing capability for scientists and engineers supporting NASA missions. Since March, more than 100 NAS users have run modeling and simulation jobs on Aitken's Rome nodes, totaling over 10,000 hours. This includes members of the NAS Division's Launch, Ascent, and Vehicle Aerodynamics (LAVA) team, who are running aircraft flow physics and aeroacoustics simulations on the Rome nodes.
“My colleagues and I have been using the new nodes extensively to run wall-modeled large eddy simulations (WMLES) using our LAVA software framework,” said Aditya Ghate, a research scientist on the team. “LAVA’s WMLES formulation is highly suited for these newer many-core processor architectures. For example, with some of our larger simulations we have noticed up to a threefold performance increase on a single AMD Rome node, compared with a single Intel Skylake node. This is particularly promising since the new nodes use only about one-and-a-half times the power of the other nodes.”
According to another LAVA team member, research scientist Gaetan Kenway, an additional benefit is that the team did not have to make any code modifications to compile their applications for the Rome nodes; a single compiler flag change was sufficient to provide an optimized build for the new architecture. “This is a stark contrast to the work required to build and optimize the code for use on GPUs,” Kenway noted.
Besides improving simulations of complex flow physics—critical to the development of safer, more efficient aircraft—Aitken is used by scientists and engineers across all NASA mission organizations to conduct a wide variety of research, from analyzing Space Launch System aerodynamics in support of the Artemis Program, to high-fidelity simulations of the launch environment at Kennedy Space Center, to Earth and space science.
“The new Rome nodes are extremely valuable for performing the large-scale simulations necessary for my research in heliophysics, astrophysics, and planetary science,” said Chuanfei Dong, a physicist at Princeton University. “With fine grid resolution, we can capture important physical and chemical processes in both micro- and macroscale. Combined with NASA's spacecraft observations, these kinds of simulations play an increasingly important role in understanding our Sun and other stars, as well as planetary atmospheres and magnetospheres, including those of Earth.”
Over the next year, NAS Division engineers plan to double the number of Rome nodes in Aitken, fully populating the first module of the energy-efficient Modular Supercomputing Facility (MSF), where the system is housed. The one-acre site where the MSF is located, near the main NAS facility at Ames, was developed with the infrastructure to support up to 16 modules for computing and data storage.
This is good news for the scientists whose research is already benefiting from the new architecture provided by this first Aitken expansion. “The new WMLES enabled by the Rome nodes are helping us improve simulation accuracy and address shortcomings in wall turbulence modeling methods as well as aeroacoustics,” Ghate said. “Without the new nodes, the detailed investigations that we are now performing would simply not be possible.”
—Michelle Moyer, NASA Ames Research Center