HPC Under the Covers: Linpack, Exascale & the Top500

By Tiffany Trader

June 28, 2018

HPCers can get painted as a monolithic bunch by outsiders, but internecine disagreements abound over the HPCest of HPC jargon, as was evident at ISC this week.

Ask four HPC leaders about Linpack’s relevance, get four distinct answers — and that’s just what happened at the Monday Top500 panel. During the panel, moderator Horst Simon (Top500 co-author and deputy lab director of Lawrence Berkeley National Lab) asked panelists Yutong Lu, Steve Conway, Thomas Schulthess and Steve Scott about the limitations surrounding Linpack and what needs to be changed at the Top500.

Yutong Lu, National Supercomputing Center in Guangzhou, China, and ISC 2019 Program Chair:

“I think the performance for the supercomputer will be the eternal target because people will always ask and care about how much faster the supercomputer could run, and what’s the highest performance that can be reached. But I think that the metrics could be changed. If you look back 20-or-more years, the computational power was the bottleneck of the full system, so the HPL was a good benchmark at that time and continued to be over the past 20 years. But now we all note that the data access and ability have become the bottleneck of the system, so we obviously need some new benchmarks to measure that part. That will be something we need to change.”

Steve Conway, COO of Hyperion Research:

“The Top500 is great as a census of elements affecting large supercomputers over time, but it’s often been interpreted–as it was never intended to be–as a predictor of performance over a spectrum of HPC code. One thing that could be valuable is a warning like on the cigarette label that says ‘this could be fatal if you use it as a predictor.’ But I was very pleased to see the attention paid to HPCG and the Green500 and the inclusion of those lists. My only recommendation would be to give those equal promotional strength.”

Thomas Schulthess, Director of the Swiss National Supercomputing Centre (CSCS):

ISC 2018 Panel: Top500’s Relevance after 25 Years

“I have quite a different opinion. The relevance today is clearly from a political point of view and a funding point of view. From an application performance point of view the story is very different. It even comes to the point where the Top500 may actually be a distraction if you have certain goals on the application side. And let me give you an example: there is the TaihuLight system in Wuxi, and the Piz Daint system that I have a lot of authority over. When you look at the flops, TaihuLight is on top with a factor of five difference. When you look at how the benchmark from the weather and climate community performs–the baroclinic instability test–then the order is reversed and the performance of Piz Daint is about two to three times faster.

“We’ve been thinking about this quite a bit…and it turns out that flops is not a good metric to design systems against. It may be good to track and look back retroactively, but not looking into the future. The conclusion is that we need a metric that relates to a scientific goal: so simulated years per day for the given size of the problem. And it is very important that the size of the problem factors in. Remember in the Top500 the HPL we do the size of the problem to maximize this metric of flops. We can do the same with HPCG. It turns out from an engineering point of view that this is not good. If you’re paid to do something, you’re not going to change your target just to maximize some number. That’s a really bad idea.

“We need to set goals. In weather and climate I think we have very clear goals that everybody can relate to, and I wish that the scientific community could come together behind a few goals rather than everybody wanting their own goal to be the metric. So not just some performance metric, but the size of the problem needs to be set, and can be varied over time. But we need to compare apples to apples, and not apples to oranges. And the last point that is really missing in the Top500 is the algorithmic or the method side. Changing algorithms in the history of computing is just as important as changing architectures.”

Steve Scott, Cray SVP and Chief Technology Officer:

“From a scientific perspective I couldn’t agree with you more. From a practical perspective I can’t agree with you at all.

“I would love to see simulated years per day as a much more interesting and useful metric, but there’s no way that you could do that. And you can’t really change the metric that the list uses because it sort of invalidates that historical record aspect. So we have to count on people that are actually doing these procurements and fielding these big systems to be sophisticated people who understand what’s really important and that Linpack is not that thing; and I absolutely think that the Top500–despite all of the good that it’s done–has caused some bad behavior. People have made decisions to get to a higher ranking on that list. And then there’ve been other people who have said ‘I’m going to buy a supercomputer and I’m not even going to put it on the list, because I don’t endorse the metric.’ I think the reality is that you’re not going to be able to change the Top500 benchmark. I like the idea of augmenting it with some things, and there’ve been some attempts with HPCG and the HPCC benchmarks. So we can augment it; I don’t think we can change it.

“I think that the HPL performance is becoming more and more disjointed from real application performance as we go forward, and memory bandwidth and interconnects and other things matter a lot more. Architectural aspects matter. As we get closer to the end of the CMOS era and we may change the way we do computing or go to completely different architectures, it may become even more strained to the point where we have to do something. But in the meantime I’m not sure there’s a whole lot we can do other that continue on the current path.”

Is it Exascale?

At ISC and on #HPC Twitter, discussion has also turned to the “true meaning” of exascale; take this tweet thread for example:

The discussion was further unpacked in this fun exchange from the ISC Analyst Crossfire put on by Intersect360 Research CEO Addison Snell with panelists Depei Qian (Sun Yat-Sen University & Beihang University), Stephan Schenk (BASF SE), Alex Bouzari (DDN), and Ian Colle (HPC at Amazon Web Services).

“Exascale is a term that’s driving me nuts because it has no exact definition,” said Snell, who proceeded to proffer variations of potential exascale definitions to get panelists’ quick takes.

The panelists all agreed that “exa-levels of something non-computational, like an exabyte of storage under one namespace or if you could magically have an exabit/sec of bandwidth” were not exascale, with one panelist offering that “exascale is whatever gets politicians to fund industry.”

The concept of whether 10 to the 18th flops per second at reduced/mixed precision should be called exascale drew one yes, another reference to funding, and consensus from the other panelists, the moderator and yours truly that that was moving the goalposts.

As for whether 10 to the 18th flops theoretical peak with no Linpack or other benchmark or application gets you to exascale, the panelists were unanimous in that it does not, with a comment that “the only thing Linpack does is it gets funding from politicians,” and another that “if our focus is on doing real work, no.”

In the final scenario, Snell asked whether exaflops for a loosely coupled non-HPC application like [email protected] counts as exascale. That drew three no’s and another nod to the market opportunity.

HPC Secrets

The open secrets of HPC are in the crosshairs this week, as illustrated by Andrew Jones’ article published by our friends at the Top500 News.

The increased prevalence of IT/Web-scale systems (close to half the list now) means it’s not in verity a list of 500 supercomputers or HPC clusters. But it was so-called list stuffing via duplicate systems (or large deployments parceled so as to optimize system share) that came to wider attention this week when Lenovo claimed 117 of the 500 machines, becoming the largest Top500 provider as measured by number of systems. It needs to be said that Lenovo didn’t invent the practice–but they have mastered it (the company lists 56 duplicate entries). It should also be said that they have not, to our knowledge, broken any rules.

A search through the annals of the list shows duplicate serial entries exist going back to at least 2010. The practice slowed down after Lenovo purchased IBM’s x86 business in 2014 and ramped up again a year later as Lenovo (and other vendors) figured out how to amplify their list presence, both through system slicing or increased benchmarking of Web/IT machines. The effect shows up as a dip in 10G Ethernet (rise in InfiniBand) and the subsequent climb of 10G Ethernet in that timeframe.

Source: Mellanox June 2018 Top500 analysis slidies

My read is that there was a collectively accepted threshold at which cloud/IT systems and creative system splicing were tolerated, and now that line may be breached. How or whether the problem will be addressed is not clear to me. It’s not as simple as removing anonymous submissions, since anonymity is requisite for industrial representation (as Jones pointed out). Hundreds of NDA site visits obviously aren’t feasible. Top500 Co-author Eric Strohmeier indicated in the Top500 press briefing on Monday that his group knows “reasonably well” who is using the anonymously listed systems; but what is more challenging is tracking down whether a submission is really configured the way it is claimed. Due to some game-playing in the past, system configurations must now be frozen, so that if systems are parceled up into small increments to get a high system count, those systems cannot then be reconfigured into a larger system to keep from falling off.

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!

Data West Brings Technology Leaders to SDSC

December 6, 2018

Data and technology enthusiasts from around the world descended upon the San Diego Supercomputing Center (SDSC) for the third annual Data West conference, which is taking place this week on the campus of the University o Read more…

By Alex Woodie

Topology Can Help Us Find Patterns in Weather

December 6, 2018

Topology--–the study of shapes-- seems to be all the rage. You could even say that data has shape, and shape matters. Shapes are comfortable and familiar concepts, so it is intriguing to see that many applications are Read more…

By James Reinders

What’s New in HPC Research: Automatic Energy Efficiency, DNA Data Analysis, Post-Exascale & More

December 6, 2018

In this bimonthly feature, HPCwire highlights newly published research in the high-performance computing community and related domains. From exascale to quantum computing, the details are here. Read more…

By Oliver Peckham

HPE Extreme Performance Solutions

AI Can Be Scary. But Choosing the Wrong Partners Can Be Mortifying!

As you continue to dive deeper into AI, you will discover it is more than just deep learning. AI is an extremely complex set of machine learning, deep learning, reinforcement, and analytics algorithms with varying compute, storage, memory, and communications needs. Read more…

IBM Accelerated Insights

Five Steps to Building a Data Strategy for AI

Our data-centric world is driving many organizations to apply advanced analytics that use artificial intelligence (AI). AI provides intelligent answers to challenging business questions. AI also enables highly personalized user experiences, built when data scientists and analysts learn new information from data that would otherwise go undetected using traditional analytics methods. Read more…

Zettascale by 2035? China Thinks So

December 6, 2018

Exascale machines (of at least a 1 exaflops peak) are anticipated to arrive by around 2020, a few years behind original predictions; and given extreme-scale performance challenges are not getting any easier, it makes sense that researchers are already looking ahead to the next big 1,000x performance goal post: zettascale computing. Read more…

By Tiffany Trader

Topology Can Help Us Find Patterns in Weather

December 6, 2018

Topology--–the study of shapes-- seems to be all the rage. You could even say that data has shape, and shape matters. Shapes are comfortable and familiar conc Read more…

By James Reinders

Zettascale by 2035? China Thinks So

December 6, 2018

Exascale machines (of at least a 1 exaflops peak) are anticipated to arrive by around 2020, a few years behind original predictions; and given extreme-scale performance challenges are not getting any easier, it makes sense that researchers are already looking ahead to the next big 1,000x performance goal post: zettascale computing. Read more…

By Tiffany Trader

Robust Quantum Computers Still a Decade Away, Says Nat’l Academies Report

December 5, 2018

The National Academies of Science, Engineering, and Medicine yesterday released a report – Quantum Computing: Progress and Prospects – whose optimism about Read more…

By John Russell

Revisiting the 2008 Exascale Computing Study at SC18

November 29, 2018

A report published a decade ago conveyed the results of a study aimed at determining if it were possible to achieve 1000X the computational power of the the Read more…

By Scott Gibson

AWS Debuts Lustre as a Service, Accelerates Data Transfer

November 28, 2018

From the Amazon re:Invent main stage in Las Vegas today, Amazon Web Services CEO Andy Jassy introduced Amazon FSx for Lustre, citing a growing body of applicati Read more…

By Tiffany Trader

AWS Launches First Arm Cloud Instances

November 28, 2018

AWS, a macrocosm of the emerging high-performance technology landscape, wants to be everywhere you want to be and offer everything you want to use (or at least Read more…

By Doug Black

Move Over Lustre & Spectrum Scale – Here Comes BeeGFS?

November 26, 2018

Is BeeGFS – the parallel file system with European roots – on a path to compete with Lustre and Spectrum Scale worldwide in HPC environments? Frank Herold Read more…

By John Russell

DOE Under Secretary for Science Paul Dabbar Interviewed at SC18

November 21, 2018

During the 30th annual SC conference in Dallas last week, SC18 hosted U.S. Department of Energy Under Secretary for Science Paul M. Dabbar. In attendance Nov. 13-14, Dabbar delivered remarks at the Top500 panel, met with a number of industry stakeholders and toured the show floor. He also met with HPCwire for an interview, where we discussed the role of the DOE in advancing leadership computing. Read more…

By Tiffany Trader

Quantum Computing Will Never Work

November 27, 2018

Amid the gush of money and enthusiastic predictions being thrown at quantum computing comes a proposed cold shower in the form of an essay by physicist Mikhail Read more…

By John Russell

Cray Unveils Shasta, Lands NERSC-9 Contract

October 30, 2018

Cray revealed today the details of its next-gen supercomputing architecture, Shasta, selected to be the next flagship system at NERSC. We've known of the code-name "Shasta" since the Argonne slice of the CORAL project was announced in 2015 and although the details of that plan have changed considerably, Cray didn't slow down its timeline for Shasta. Read more…

By Tiffany Trader

IBM at Hot Chips: What’s Next for Power

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, Read more…

By Tiffany Trader

House Passes $1.275B National Quantum Initiative

September 17, 2018

Last Thursday the U.S. House of Representatives passed the National Quantum Initiative Act (NQIA) intended to accelerate quantum computing research and developm Read more…

By John Russell

CERN Project Sees Orders-of-Magnitude Speedup with AI Approach

August 14, 2018

An award-winning effort at CERN has demonstrated potential to significantly change how the physics based modeling and simulation communities view machine learni Read more…

By Rob Farber

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

AMD Sets Up for Epyc Epoch

November 16, 2018

It’s been a good two weeks, AMD’s Gary Silcott and Andy Parma told me on the last day of SC18 in Dallas at the restaurant where we met to discuss their show news and recent successes. Heck, it’s been a good year. Read more…

By Tiffany Trader

US Leads Supercomputing with #1, #2 Systems & Petascale Arm

November 12, 2018

The 31st Supercomputing Conference (SC) - commemorating 30 years since the first Supercomputing in 1988 - kicked off in Dallas yesterday, taking over the Kay Ba Read more…

By Tiffany Trader

Leading Solution Providers

SC 18 Virtual Booth Video Tour

Advania @ SC18 AMD @ SC18
ASRock Rack @ SC18
DDN Storage @ SC18
HPE @ SC18
IBM @ SC18
Lenovo @ SC18 Mellanox Technologies @ SC18
NVIDIA @ SC18
One Stop Systems @ SC18
Oracle @ SC18 Panasas @ SC18
Supermicro @ SC18 SUSE @ SC18 TYAN @ SC18
Verne Global @ SC18

TACC’s ‘Frontera’ Supercomputer Expands Horizon for Extreme-Scale Science

August 29, 2018

The National Science Foundation and the Texas Advanced Computing Center announced today that a new system, called Frontera, will overtake Stampede 2 as the fast Read more…

By Tiffany Trader

HPE No. 1, IBM Surges, in ‘Bucking Bronco’ High Performance Server Market

September 27, 2018

Riding healthy U.S. and global economies, strong demand for AI-capable hardware and other tailwind trends, the high performance computing server market jumped 28 percent in the second quarter 2018 to $3.7 billion, up from $2.9 billion for the same period last year, according to industry analyst firm Hyperion Research. Read more…

By Doug Black

Nvidia’s Jensen Huang Delivers Vision for the New HPC

November 14, 2018

For nearly two hours on Monday at SC18, Jensen Huang, CEO of Nvidia, presented his expansive view of the future of HPC (and computing in general) as only he can do. Animated. Backstopped by a stream of data charts, product photos, and even a beautiful image of supernovae... Read more…

By John Russell

Germany Celebrates Launch of Two Fastest Supercomputers

September 26, 2018

The new high-performance computer SuperMUC-NG at the Leibniz Supercomputing Center (LRZ) in Garching is the fastest computer in Germany and one of the fastest i Read more…

By Tiffany Trader

Houston to Field Massive, ‘Geophysically Configured’ Cloud Supercomputer

October 11, 2018

Based on some news stories out today, one might get the impression that the next system to crack number one on the Top500 would be an industrial oil and gas mon Read more…

By Tiffany Trader

Intel Confirms 48-Core Cascade Lake-AP for 2019

November 4, 2018

As part of the run-up to SC18, taking place in Dallas next week (Nov. 11-16), Intel is doling out info on its next-gen Cascade Lake family of Xeon processors, specifically the “Advanced Processor” version (Cascade Lake-AP), architected for high-performance computing, artificial intelligence and infrastructure-as-a-service workloads. Read more…

By Tiffany Trader

Google Releases Machine Learning “What-If” Analysis Tool

September 12, 2018

Training machine learning models has long been time-consuming process. Yesterday, Google released a “What-If Tool” for probing how data point changes affect a model’s prediction. The new tool is being launched as a new feature of the open source TensorBoard web application... Read more…

By John Russell

The Convergence of Big Data and Extreme-Scale HPC

August 31, 2018

As we are heading towards extreme-scale HPC coupled with data intensive analytics like machine learning, the necessary integration of big data and HPC is a curr Read more…

By Rob Farber

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