After months of labor unpacking, installing, and deploying the various subsystems and supporting infrastructure, Los Alamos National Laboratory’s (LANL) latest super, the Crossroads plot, has been installed.
This big beast is tasked with one of many US Department of Energy’s (DoE) most secretive workloads: making particular America’s nuclear stockpile actually works ought to peaceful the dark day come that it be ever crucial.
The US can’t exactly crawl out and test at its nuclear arsenal peaceful works by atmosphere a form of warheads off, so the DoE makes employ of supercomputers to simulate the storage, maintenance, and efficacy of the weapons instead. (It does carry out some sub-critical physical experiments, but simulations are crucial.)
“Crossroads represents a significant advance in the nation’s ability to assess the safety of the stockpile, as well as modernizing the deterrent to meet a contemporary national security landscape,” Charlie Nakhleh, associate lab director for Weapons Physics at Los Alamos, said in a write-up.
Crossroads is LANL’s latest plot to inherit this duty, taking over from the aging Trinity plot. The latest plot was developed by HPE’s Cray division, but no longer like ORNL’s 1.1 exaFLOPS Frontier plot or Argonne’s newly installed Aurora, Crossroads is no longer any longer GPU accelerated.
(Crossroads as a name is an apt alternative: Operation Crossroads was the code-name given to two atomic bomb tests by America in 1946, the first such tests after the famous Trinity detonation in 1945, depicted on this summer’s smash-hit film Oppenheimer.)
Brooding about most of the FLOPS delivered by contemporary supercomputers come from GPUs, no longer CPUs, this may appear love a strange omission for Crossroads. Nevertheless, as researchers at LANL famous, various workloads have various bottlenecks, and when it comes to simulating nuclear weapons, reminiscence is a big one.
“Given the hoopla in the click around the ‘fastest supercomputer on the planet,’ one may contemplate we ought to peaceful purchase computers with the most FLOPS,” Gary Grider, who heads up LANL’s HPC division, said.
“Every class of instruct requires a various balance of FLOPS, reminiscence measurement, and reminiscence access. For the considerations we are engaged on, the time it takes to salvage a result is mainly optimistic by reminiscence measurement and reminiscence access, no longer FLOPS.”
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So, rather than packing the plot fat of graphics processors, Crossroads was optimized around reminiscence. As our sibling outlet The Next Platform discussed in its preview of the Crossroads equipment last year, whereas LANL hasn’t revealed mighty by way of specifics about the plot, it reportedly makes employ of a combination of Intel’s Sapphire Rapids Xeon Scalable and high-bandwidth reminiscence Xeon Max processors.
The lab appeared to affirm the latter in its announcement this week, noting that high-bandwidth reminiscence “brings reminiscence without delay to the processing chip.” Intel’s Xeon Max processors pack up to 64GB of on-package HBM2e reminiscence and 56 CPU cores into a single package capable of 1TB/s of reminiscence bandwidth. For reference, that’s more than twice the bandwidth AMD’s 12-channel Epyc 4 CPUs can bring when utilizing standard DDR5 modules.
According to LANL, Crossroads ought to peaceful bring roughly 4x-8x the performance of Trinity. That plot, launched in 2015, is capable of 41.46 petaFLOPS of peak FP64 performance, although in reality the plot simplest managed about half that in the LINPACK benchmark.
“It hardly ever happens in computing that you can transfer to a contemporary plot and gawk big gains without changing the codes,” Grider said in the write-up. “However the switch from Trinity to Crossroads will make moral that.”
Crossroads itself is supported by three smaller programs, Rocinante, Razorback, and Tycho, which have been named after ships and stations from The Expanse science fiction novels and tv series.
According to LANL, Rocinante is an application regression plot, a miniaturized version of the fat Crossroads plot which can be archaic to test code in an unclassified ambiance. Razorback serves a similar blueprint, but rather than catering to developers and scientists, the plot offers a testing ambiance for preparing, testing, and deploying patches and updates in a controlled ambiance ahead of pushing them out to the fat plot.
Finally Tycho, which was among the first Crossroads programs delivered last year, is based on a similar architecture as the fat plot, but instead of HBM makes employ of conventional reminiscence. According to LANL this offers compute cycles to “stockpile simulation users who otherwise may have been waiting for Crossroads.”
With the plot is now installed, lab crews and techs are working to hasten initial diagnostics on the fat plot. LANL expects to start the machine to National Nuclear Safety Administration labs, which also comprises Sandia and Lawrence Livermore National Labs, this fall. ®