IBM at Hot Chips: What’s Next for Power

By Tiffany Trader

August 23, 2018

With processor, memory and networking technologies all racing to fill in for an ailing Moore’s law, the era of the heterogeneous datacenter is well underway, and IBM is positioning its chips to be the air traffic controller at the center of it all. That was the high-level takeway of our interview with IBM Power architects Jeff Stuecheli and Bill Starke at Hot Chips this week.

The accomplished engineers were at the 30th iteration of Hot Chips to focus on the Power9 scale-up chips and servers, but they also provided details on upcoming developments in the roadmap, including a new buffered memory system suitable for scale-out processors.

Source: IBM slide (Hot Chips 30)

Having launched both the scale-out and scale-up Power9s, IBM is now working on a third P9 variant with “advanced I/O,” featuring IBM’s 25 GT/s PowerAXON signaling technology with upgraded OpenCAPI and NVLink protocols, and a new open standard for buffered memory.

AXON is an inspired appellation that the Power engineering team came up with and the IBM marketing team signed off on. The A and X are designations for IBM’s SMP buses – X links are on-module and A links are off; the O and N stand for OpenCAPI and NVLINK, respectively. The convenient acronym would be fine at that, but aligning with IBM’s penchant for cognitive computing, axons are the brain’s signalling devices, allowing neurons to communicate, so you could say, as Witnix founder and former Harvard HPC guy James Cuff did, that AI is literally “built right into the wire.”

You can see on these annotated Power9 die shots how going from a DDR memory controller to a redrive memory controller and going to smaller PHYs enabled IBM to double the number of AXON lanes.

“The PowerAXON concept gives us a lot of flexibility,” said Stuecheli. “One chip can be deployed to be a big SMP, it can be deployed to talk to lots of GPUs, it can talk to a mix of FPGAs and GPUs – that’s really our goal here is to build a processor that can then be customized toward these domain specific applications.”

For its future products, IBM is focusing on lots of lanes and lots of frequency. Its Power10 roadmap incorporates 32 GT/s signalling technology that will be able to run in 50 GT/s mode.

The idea that IO is composable is what OpenCAPI and PowerAXON are all about – and now IBM is bringing this same ethos to memory through the development of an open standard for buffered memory, appropriately called OpenCAPI memory.

With both Power8 and Power9, the chips made for scale-out boxes support direct-attached memory, while the scale-up variants, intended for machines with more than two sockets, employ buffered memory. The buffered memory system puts DRAM chips right next to IBM’s Centaur buffer chip (see figure below-right), enabling a large number of DDR channels to be funneled into one processor over SERDES. The agnostic interface hides the exact memory technology that’s on the DIMM from the processor, so the processor can work with different kinds of memory. This decoupling of memory technology from the processor technology means that, for example, enterprise customers upgrading from Power8 to Power9 can keep their existing DDR4 DRAM DIMMs.

Power9 Scale Up chipset block diagram

Stuecheli shared that the current buffered memory system (on Power8 and Power9 SU chips) adds a latency of approximately 10 nanoseconds compared to direct attached. This minimal overhead was accomplished “through careful framing of the packets as they go across the SERDES and bypasses in the DDR scheduling,” said Stuecheli.

While the Centaur-based approach is enterprise-focused, IBM wanted to offer the same buffered memory in its scale-out products. They are planning to introduce this capability as an open standard in the third (and presumably final) Power9 variant, due out in 2019. “We’ve been working through JEDEC to build memory DIMMs based around a thin buffer design,” said Stuecheli. “If you have an accelerator and you don’t like having that big expensive DDR PHY on it and you want to use just traditional SERDES to talk to memory you can do so with the new standardized memory interface we’re building,” he told the audience at Hot Chips. The interface spans from 1U small memory form factors all the way up to big tall DIMMs. The aim is to have an agnostic interface that attaches to a variety of memory types to it, whether that’s storage-class memory, or very high bandwidth, low capacity memory.

While the latency add was 10 nanoseconds on the proprietary design (with one port going to four DDR ports with a 16MB cache lookup), the new buffer IBM is building is a single port design with a single interface. It’s a much smaller chip without the cache, and IBM thinks it can reduce this latency to 5 nanoseconds. Stuecheli said that company-run simulations with loaded latency showed it doesn’t take much load at all before providing much lower latency than a direct-attached solution.

The roadmap shows the anticipated increase in memory bandwidth owing to the new memory system. Where the Power9 SU chip offers 210 GB/s of memory bandwidth (and Stuecheli says it’s actually closer to 230 GB/s), the next Power9 derivative chip, with the new memory technology, will be capable of deploying 350 GB/s per socket of bandwidth, according to Stuecheli.

“If you’re in HPC and disappointed in your bytes-per-flop ratio, that’s a pretty big improvement,” he said, adding “we’re taking what was essentially the Power10 memory subsystem and implementing that in Power9.” With Power10 bringing in DDR5, IBM expects to surpass 435 GB/s sustained memory bandwidth.

IBM believes that it has the right approach to push past DDR limitations. “When you think of Moore’s law kind of winding down, slowing down, you think of single-ended signaling with DDR memory slowing down,” Bill Starke said in a pre-briefing. “This composable system construct [that IBM is architecting] is enabling a proliferation of more heterogeneity in compute technology, along with a wider variation of memory technologies, all in this composable plug-and-play, put-it-together-how-you-want way where it’s all about a big high-bandwidth low-latency switching infrastructure.”

“With the flexibility of the attach on the memory side and on the compute acceleration side, it really boils down to thinking of the CPU chip as this big switch,” Stuecheli followed, “this big data switch that’s just one big pile of bandwidth connectivity that’s enabling any kind of memory to talk to any kind of acceleration, and it all plumbs right past the powerful general-purpose processor cores, so you’re pulling that whole compute estate together.”

HPC analyst Addison Snell (CEO of Intersect360 Research) came away from Tuesday’s Hot Chips talk with a favorable impression of the Power play. “IBM’s presentation at Hot Chips underscored two major themes,” Snell commented by email. “One, Power9 has excellent memory bandwidth and performance. Two, it is a great platform for attaching accelerators or co-processors. It’s an odd statement of direction, but maybe a visionary one, essentially saying a processor isn’t about computation per se, but rather it’s about feeding data to other computational elements.”

Subscribe to HPCwire's Weekly Update!

Be the most informed person in the room! Stay ahead of the tech trends with industy updates delivered to you every week!

U.S. CTO Michael Kratsios Adds DoD Research & Engineering Title

July 13, 2020

Michael Kratsios, the U.S. Chief Technology Officer, has been appointed acting Undersecretary of Defense for research and engineering. He replaces Mike Griffin, who along with his deputy Lis Porter, stepped down last wee Read more…

By John Russell

Supercomputer Research Reveals Star Cluster Born Outside Our Galaxy

July 11, 2020

The Milky Way is our galactic home, containing our solar system and continuing into a giant band of densely packed stars that stretches across clear night skies around the world – but, it turns out, not all of those st Read more…

By Oliver Peckham

Max Planck Society Begins Installation of Liquid-Cooled Supercomputer from Lenovo

July 9, 2020

Lenovo announced today that it is supplying a new high performance computer to the Max Planck Society, one of Germany's premier research organizations. Comprised of Intel Xeon processors and Nvidia A100 GPUs, and featuri Read more…

By Tiffany Trader

Xilinx Announces First Adaptive Computing Challenge

July 9, 2020

A new contest is challenging the computing world. Xilinx has announced the first Xilinx Adaptive Computing Challenge, a competition that will task developers and startups with finding creative workload acceleration solutions. Xilinx is running the Adaptive Computing Challenge in partnership with, a developing community... Read more…

By Staff report

Reviving Moore’s Law? LBNL Researchers See Promise in Heterostructure Oxides

July 9, 2020

The reality of Moore’s law’s decline is no longer doubted for good empirical reasons. That said, never say never. Recent work by Lawrence Berkeley National Laboratory researchers suggests heterostructure oxides may b Read more…

By John Russell

AWS Solution Channel

Best Practices for Running Computational Fluid Dynamics (CFD) Workloads on AWS

The scalable nature and variable demand of CFD workloads makes them well-suited for a cloud computing environment. Many of the AWS instance types, such as the compute family instance types, are designed to include support for this type of workload.  Read more…

Intel® HPC + AI Pavilion

Supercomputing the Pandemic: Scientific Community Tackles COVID-19 from Multiple Perspectives

Since their inception, supercomputers have taken on the biggest, most complex, and most data-intensive computing challenges—from confirming Einstein’s theories about gravitational waves to predicting the impacts of climate change. Read more…

President’s Council Targets AI, Quantum, STEM; Recommends Spending Growth

July 9, 2020

Last week the President Council of Advisors on Science and Technology (PCAST) met (webinar) to review policy recommendations around three sub-committee reports: 1) Industries of the Future (IotF), chaired be Dario Gil (d Read more…

By John Russell

Max Planck Society Begins Installation of Liquid-Cooled Supercomputer from Lenovo

July 9, 2020

Lenovo announced today that it is supplying a new high performance computer to the Max Planck Society, one of Germany's premier research organizations. Comprise Read more…

By Tiffany Trader

President’s Council Targets AI, Quantum, STEM; Recommends Spending Growth

July 9, 2020

Last week the President Council of Advisors on Science and Technology (PCAST) met (webinar) to review policy recommendations around three sub-committee reports: Read more…

By John Russell

Google Cloud Debuts 16-GPU Ampere A100 Instances

July 7, 2020

On the heels of the Nvidia’s Ampere A100 GPU launch in May, Google Cloud is announcing alpha availability of the A100 “Accelerator Optimized” VM A2 instance family on Google Compute Engine. The instances are powered by the HGX A100 16-GPU platform, which combines two HGX A100 8-GPU baseboards using... Read more…

By Tiffany Trader

Q&A: HLRS’s Bastian Koller Tackles HPC and Industry in Germany and Europe

July 6, 2020

In this exclusive interview for HPCwire – sadly not face to face – Steve Conway, senior advisor for Hyperion Research, talks with Dr.-Ing Bastian Koller about the state of HPC and its collaboration with Industry in Europe. Koller is a familiar figure in HPC. He is the managing director at High Performance Computing Center Stuttgart (HLRS) and also serves... Read more…

By Steve Conway, Hyperion

OpenPOWER Reboot – New Director, New Silicon Partners, Leveraging Linux Foundation Connections

July 2, 2020

Earlier this week the OpenPOWER Foundation announced the contribution of IBM’s A21 Power processor core design to the open source community. Roughly this time Read more…

By John Russell

Hyperion Forecast – Headwinds in 2020 Won’t Stifle Cloud HPC Adoption or Arm’s Rise

June 30, 2020

The semiannual taking of HPC’s pulse by Hyperion Research – late fall at SC and early summer at ISC – is a much-watched indicator of things come. This yea Read more…

By John Russell

Racism and HPC: a Special Podcast

June 29, 2020

Promoting greater diversity in HPC is a much-discussed goal and ostensibly a long-sought goal in HPC. Yet it seems clear HPC is far from achieving this goal. Re Read more…

Top500 Trends: Movement on Top, but Record Low Turnover

June 25, 2020

The 55th installment of the Top500 list saw strong activity in the leadership segment with four new systems in the top ten and a crowning achievement from the f Read more…

By Tiffany Trader

Supercomputer Modeling Tests How COVID-19 Spreads in Grocery Stores

April 8, 2020

In the COVID-19 era, many people are treating simple activities like getting gas or groceries with caution as they try to heed social distancing mandates and protect their own health. Still, significant uncertainty surrounds the relative risk of different activities, and conflicting information is prevalent. A team of Finnish researchers set out to address some of these uncertainties by... Read more…

By Oliver Peckham

[email protected] Turns Its Massive Crowdsourced Computer Network Against COVID-19

March 16, 2020

For gamers, fighting against a global crisis is usually pure fantasy – but now, it’s looking more like a reality. As supercomputers around the world spin up Read more…

By Oliver Peckham

[email protected] Rallies a Legion of Computers Against the Coronavirus

March 24, 2020

Last week, we highlighted [email protected], a massive, crowdsourced computer network that has turned its resources against the coronavirus pandemic sweeping the globe – but [email protected] isn’t the only game in town. The internet is buzzing with crowdsourced computing... Read more…

By Oliver Peckham

Supercomputer Simulations Reveal the Fate of the Neanderthals

May 25, 2020

For hundreds of thousands of years, neanderthals roamed the planet, eventually (almost 50,000 years ago) giving way to homo sapiens, which quickly became the do Read more…

By Oliver Peckham

DoE Expands on Role of COVID-19 Supercomputing Consortium

March 25, 2020

After announcing the launch of the COVID-19 High Performance Computing Consortium on Sunday, the Department of Energy yesterday provided more details on its sco Read more…

By John Russell

Neocortex Will Be First-of-Its-Kind 800,000-Core AI Supercomputer

June 9, 2020

Pittsburgh Supercomputing Center (PSC - a joint research organization of Carnegie Mellon University and the University of Pittsburgh) has won a $5 million award Read more…

By Tiffany Trader

Honeywell’s Big Bet on Trapped Ion Quantum Computing

April 7, 2020

Honeywell doesn’t spring to mind when thinking of quantum computing pioneers, but a decade ago the high-tech conglomerate better known for its control systems waded deliberately into the then calmer quantum computing (QC) waters. Fast forward to March when Honeywell announced plans to introduce an ion trap-based quantum computer whose ‘performance’ would... Read more…

By John Russell

10nm, 7nm, 5nm…. Should the Chip Nanometer Metric Be Replaced?

June 1, 2020

The biggest cool factor in server chips is the nanometer. AMD beating Intel to a CPU built on a 7nm process node* – with 5nm and 3nm on the way – has been i Read more…

By Doug Black

Leading Solution Providers


Nvidia’s Ampere A100 GPU: Up to 2.5X the HPC, 20X the AI

May 14, 2020

Nvidia's first Ampere-based graphics card, the A100 GPU, packs a whopping 54 billion transistors on 826mm2 of silicon, making it the world's largest seven-nanom Read more…

By Tiffany Trader

‘Billion Molecules Against COVID-19’ Challenge to Launch with Massive Supercomputing Support

April 22, 2020

Around the world, supercomputing centers have spun up and opened their doors for COVID-19 research in what may be the most unified supercomputing effort in hist Read more…

By Oliver Peckham

Australian Researchers Break All-Time Internet Speed Record

May 26, 2020

If you’ve been stuck at home for the last few months, you’ve probably become more attuned to the quality (or lack thereof) of your internet connection. Even Read more…

By Oliver Peckham

15 Slides on Programming Aurora and Exascale Systems

May 7, 2020

Sometime in 2021, Aurora, the first planned U.S. exascale system, is scheduled to be fired up at Argonne National Laboratory. Cray (now HPE) and Intel are the k Read more…

By John Russell

Summit Supercomputer is Already Making its Mark on Science

September 20, 2018

Summit, now the fastest supercomputer in the world, is quickly making its mark in science – five of the six finalists just announced for the prestigious 2018 Read more…

By John Russell

TACC Supercomputers Run Simulations Illuminating COVID-19, DNA Replication

March 19, 2020

As supercomputers around the world spin up to combat the coronavirus, the Texas Advanced Computing Center (TACC) is announcing results that may help to illumina Read more…

By Staff report

$100B Plan Submitted for Massive Remake and Expansion of NSF

May 27, 2020

Legislation to reshape, expand - and rename - the National Science Foundation has been submitted in both the U.S. House and Senate. The proposal, which seems to Read more…

By John Russell

John Martinis Reportedly Leaves Google Quantum Effort

April 21, 2020

John Martinis, who led Google’s quantum computing effort since establishing its quantum hardware group in 2014, has left Google after being moved into an advi Read more…

By John Russell

  • arrow
  • Click Here for More Headlines
  • arrow
Do NOT follow this link or you will be banned from the site!
Share This