Quadrics Delivers Integral Interconnection

By Nicole Hemsoth

November 4, 2005

HPCwire recently sat down with Moray McLaren, research and development manager at Quadrics Ltd., a leading supplier and developer of high performance networking products and resource management software. The company's applied advanced technology builds clusters that deliver supercomputing levels of performance and reliability. Its QsNet products are based on internally developed ASICs, firmware and software technologies. With a fine track record of working in partnership with other HPC companies as well as organizations such as Lawrence Livermore and Los Alamos National Laboratories, the Pittsburgh Supercomputer Center and Pacific Northwest National Laboratory, Quadrics is at the forefront of helping solve some of the world's most complex computational challenges.

HPCwire: Interconnect vendors such as Quadrics make a lot of their low message latency these days, but how far is this really a measure of capability of an interconnect?

McLaren: Simple latency measurements can give an indication of the potential of an interconnect, but you need to be careful that they are measured in the way that the interconnect will actually be used in the final system. For example, latency is typically measured across just a pair nodes, but when the final system scales up to thousands [of nodes], then you need to consider scaling in both the hardware and software. It's fairly obvious the worst-case hardware latency across a larger network will be higher as you have to traverse more switches, but in some cases the software latencies are higher too since they have to employ different buffer structures for larger scale networks. At Quadrics, we use the same software across all sizes of network. We have ultra low hop latency in our switch so as to reduce the hardware scaling factor

HPCwire: So does the choice of MPI stack effect the measured latency?

McLaren: Surprisingly, not as much as you would think. At Quadrics, we support the Scali, Intel and HP multi-platform MPIs. The simple end-to-end latency is similar across all of them. The Scali and Intel implementations map onto the DAPL abstraction layer. Since the basic transfer mechanism is a remote write operation, which maps very closely onto the mechanisms of the base hardware, there's little overhead here. The problem with MPI implementations that are based on simple puts is that they required order(N) buffer space. This is acceptable for systems of a few hundreds of nodes, but on a 1,000-way network, this can be a significant fraction of the node memory. The way around this is to use a common queue, with the network interface allocating the buffer space. This requires more intelligence on the network interface and can add to latency.

HPCwire: How would you expect it to vary with node architecture?

McLaren: The devil is in the detail here. The actual CPU architecture choice — and even to some extent, the bus choice — are not as important as how “close” the IO bus is to the main memory. In common with most vendors, our current best case latencies are measured on the Opteron platform. But this is as much factor of the integration of the Opteron memory system, as to Hypertransport. In fact, our standard QsNet II adapters produce similar low latencies to other NICs developed specifically for Hypertransport. Newer Intel platforms that bring the PCI- Express interface closer to the memory system are starting to close the gap

When you start looking at larger NUMA systems, then it becomes much more complex, since the latency varies depending on which CPU group you are in and the location on the source and destination memory buffer. At Quadrics, we support multiple rails of interconnect. In this case, the software automatically allocates the communication to the lowest latency adapter.

HPCwire: Would using other APIs give deliver a lower latency result?

McLaren: The Cray Shmem message layer is a simple “put get” mechanism and as such maps well onto any interconnect based on put-and-get. The other key advantage is there is no unnecessary sequentialization of messages. In Shmem, there is effectively a relaxed store order model, which gives the hardware the maximum opportunity to handle communications in parallel. For this reason, it's also a good fit for multi-threaded applications that need to communicate.

HPCwire: Quadrics makes a big deal about collectives performance. Why is this important?

McLaren: If you have a code that has been structured to make extensive use of collective operations, then by having a high performance, highly scalable collective implementation, you can insure that the code will scale well to large numbers of nodes. In our collectives implementation, we actually do the double precision floating point operations on the processor embedded in the network interface. This saves the delays of passing results back and forth across the IO bus to the main processor.

HPCwire: Then aren't bandwidth measures much more straightforward?

McLaren: Since bandwidth is measured over large messages, it is typically less sensitive to software issues. However, you need to watch for people quoting throughput bandwidth, for where a number of simultaneous transfers are used to saturate the link, compared to the bandwidth for a single message transfer. As the message length becomes very large, you can start to run into limitations with the size of mapping hardware or with lock down caches. On Quadrics NICs, we implement a full Memory Management Unit capable of mirroring the main processors VM mappings to avoid this limitation.

HPCwire: So given the limitations of simple benchmarks, wouldn't it be better to test everything with the final applications?

McLaren: For limited size systems, this is indeed preferable, but for the very largest systems this just isn't practical. The good thing about the more straightforward communications benchmarks is that, for a well designed interconnect, the scaling performance is usually very predictable. When you run a complex application, then Amdahl's law means that predicting the performance is much more complex. However, at least if you start with an platforms designed from the outset for scalability, the programmer can concentrate on any potential issues within the code, without being concerned that a performance problem is an artefact of the underlying hardware.

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!

Supercomputers Streamline Prediction of Dangerous Arrhythmia

June 2, 2020

Heart arrhythmia can prove deadly, contributing to the hundreds of thousands of deaths from cardiac arrest in the U.S. every year. Unfortunately, many of those arrhythmia are induced as side effects from various medicati Read more…

By Staff report

Indiana University to Deploy Jetstream 2 Cloud with AMD, Nvidia Technology

June 2, 2020

Indiana University has been awarded a $10 million NSF grant to build ‘Jetstream 2,’ a cloud computing system that will provide 8 aggregate petaflops of computing capability in support of data analysis and AI workload Read more…

By Tiffany Trader

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 instrumental to AMD’s datacenter market resurgence. Nanomet Read more…

By Doug Black

Supercomputer-Powered Protein Simulations Approach Lab Accuracy

June 1, 2020

Protein simulations have dominated the supercomputing conversation of late as supercomputers around the world race to simulate the viral proteins of COVID-19 as accurately as possible and simulate potential bindings in t Read more…

By Oliver Peckham

HPC Career Notes: June 2020 Edition

June 1, 2020

In this monthly feature, we'll keep you up-to-date on the latest career developments for individuals in the high-performance computing community. Whether it's a promotion, new company hire, or even an accolade, we've got Read more…

By Mariana Iriarte

AWS Solution Channel

Computational Fluid Dynamics on AWS

Over the past 30 years Computational Fluid Dynamics (CFD) has grown to become a key part of many engineering design processes. From aircraft design to modelling the blood flow in our bodies, the ability to understand the behaviour of fluids has enabled countless innovations and improved the time to market for many products. Read more…

Supercomputer Modeling Shows How COVID-19 Spreads Through Populations

May 30, 2020

As many states begin to loosen the lockdowns and stay-at-home orders that have forced most Americans inside for the past two months, researchers are poring over the data, looking for signs of the dreaded second peak of t Read more…

By Oliver Peckham

Indiana University to Deploy Jetstream 2 Cloud with AMD, Nvidia Technology

June 2, 2020

Indiana University has been awarded a $10 million NSF grant to build ‘Jetstream 2,’ a cloud computing system that will provide 8 aggregate petaflops of comp Read more…

By Tiffany Trader

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

COVID-19 HPC Consortium Expands to Europe, Reports on Research Projects

May 28, 2020

The COVID-19 HPC Consortium, a public-private effort delivering free access to HPC processing for scientists pursuing coronavirus research – some utilizing AI Read more…

By Doug Black

$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

IBM Boosts Deep Learning Accuracy on Memristive Chips

May 27, 2020

IBM researchers have taken another step towards making in-memory computing based on phase change (PCM) memory devices a reality. Papers in Nature and Frontiers Read more…

By John Russell

Hats Over Hearts: Remembering Rich Brueckner

May 26, 2020

HPCwire and all of the Tabor Communications family are saddened by last week’s passing of Rich Brueckner. He was the ever-optimistic man in the Red Hat presiding over the InsideHPC media portfolio for the past decade and a constant presence at HPC’s most important events. Read more…

Nvidia Q1 Earnings Top Expectations, Datacenter Revenue Breaks $1B

May 22, 2020

Nvidia’s seemingly endless roll continued in the first quarter with the company announcing blockbuster earnings that exceeded Wall Street expectations. Nvidia Read more…

By Doug Black

Microsoft’s Massive AI Supercomputer on Azure: 285k CPU Cores, 10k GPUs

May 20, 2020

Microsoft has unveiled a supercomputing monster – among the world’s five most powerful, according to the company – aimed at what is known in scientific an Read more…

By Doug Black

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

Global Supercomputing Is Mobilizing Against COVID-19

March 12, 2020

Tech has been taking some heavy losses from the coronavirus pandemic. Global supply chains have been disrupted, virtually every major tech conference taking place over the next few months has been canceled... 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

Steve Scott Lays Out HPE-Cray Blended Product Roadmap

March 11, 2020

Last week, the day before the El Capitan processor disclosures were made at HPE's new headquarters in San Jose, Steve Scott (CTO for HPC & AI at HPE, and former Cray CTO) was on-hand at the Rice Oil & Gas HPC conference in Houston. He was there to discuss the HPE-Cray transition and blended roadmap, as well as his favorite topic, Cray's eighth-gen networking technology, Slingshot. 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

Leading Solution Providers

SC 2019 Virtual Booth Video Tour

AMD
AMD
ASROCK RACK
ASROCK RACK
AWS
AWS
CEJN
CJEN
CRAY
CRAY
DDN
DDN
DELL EMC
DELL EMC
IBM
IBM
MELLANOX
MELLANOX
ONE STOP SYSTEMS
ONE STOP SYSTEMS
PANASAS
PANASAS
SIX NINES IT
SIX NINES IT
VERNE GLOBAL
VERNE GLOBAL
WEKAIO
WEKAIO

Contributors

Tech Conferences Are Being Canceled Due to Coronavirus

March 3, 2020

Several conferences scheduled to take place in the coming weeks, including Nvidia’s GPU Technology Conference (GTC) and the Strata Data + AI conference, have Read more…

By Alex Woodie

Exascale Watch: El Capitan Will Use AMD CPUs & GPUs to Reach 2 Exaflops

March 4, 2020

HPE and its collaborators reported today that El Capitan, the forthcoming exascale supercomputer to be sited at Lawrence Livermore National Laboratory and serve Read more…

By John Russell

‘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

Cray to Provide NOAA with Two AMD-Powered Supercomputers

February 24, 2020

The United States’ National Oceanic and Atmospheric Administration (NOAA) last week announced plans for a major refresh of its operational weather forecasting supercomputers, part of a 10-year, $505.2 million program, which will secure two HPE-Cray systems for NOAA’s National Weather Service to be fielded later this year and put into production in early 2022. Read more…

By Tiffany Trader

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

Fujitsu A64FX Supercomputer to Be Deployed at Nagoya University This Summer

February 3, 2020

Japanese tech giant Fujitsu announced today that it will supply Nagoya University Information Technology Center with the first commercial supercomputer powered Read more…

By Tiffany Trader

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

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