AMD reportedly working on a monster exascale APU

It comes with 32 cores plus an advanced new GPU core. Can it save the company?


Just a week ago, President Barack Obama signed an executive order for a coordinated federal strategy into HPC to build the world's first exascale supercomputer. The Department of Energy, the Department of Defense (DoD), and the National Science Foundation (NSF) will work on the project.

Of course, the HPC world has been talking about exascale for a while, as have the major players. IBM and Intel are in a race of their own to get to exascale.

But what about AMD? Stop laughing, I'm serious.

Thanks to a paper submitted to Institute of Electrical and Electronics Engineers, otherwise known as IEEE, AMD has tipped its plans for what it calls an "Exascale Heterogeneous Processor," or EHP, with 32 of its new Zen cores, a huge new GPU die called "Greenland," and up to 32GB of High Bandwidth Memory 2 memory – all on a 2.5D interposer.

Zen is the codename for a new core being designed by CPU design wiz Jim Keller, who designed the 64-bit x86 extensions and HyperTransport interconnects for the AMD Athlon more than a decade ago. Zen is believed to be a clean sheet design, new from the ground up and a significant advance over the current designs.

The white paper abstract says in part:

To fully realize the capabilities of the GPU, we envision exascale compute nodes comprised of integrated CPUs and GPUs (i.e., accelerated processing units or APUs) along with the hardware and software support to enable scientists to effectively run their scientific experiments on an exascale system. [In the paper submitted to IEEE...] We discuss the hardware and software challenges in building a heterogeneous exascale system, and we describe on-going research efforts at AMD to realize our exascale vision.

The paper requires membership to access, but an Italian chip site managed to get it and found a diagram that gives an idea of the processor. It has 32 Zen cores surrounding the Greenland GPU core plus eight 4GB stacks of stacked HMB memory. Greenland has not been announced, so it's obviously a next generation design, since all of AMD's codenames for its GPUs have been south Pacific islands. The next generation is said to be "Arctic Islands," so Greenland is likely the first in the new generation.

Now there's a bit of a conflict among rumor mills. While WCCFtech was the first to report on the 32-core design, the unfortunately-named hobbyist site Fudzilla is saying it's a 16-core, 32-thread design. WCCFtech also believes there is a 16-core variant in the works, but it is standing by the 32-core design as well.

It's known that Zen will have significantly improved multithreading over the current design, and both WCCFtech and Fudzilla have gotten it right quite often, a lot more than DigiTimes, so I'm not sure who to believe. Maybe both.

Other details on this megachip include 64 lanes of PCI Express Gen 3, 14 lanes of SATA III, 4-channel DDR4 with a total capacity of 256GB per channel and a new memory interconnect called Global Memory Interconnect that will act as an interface between the Zen die and Greenland die or between the two chips on the same multi-chip module package.

It's still all speculation of course. But for once, it's good speculation. The only question is how hard will AMD come back after pretty much ceding the server market. Well, there's that and one more question: can AMD hang on? The mystery chip is not due until 2016 or 2017 and the company has taken it on the chin lately. Here's to hoping AMD can hang in there.

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