The Ultimate Debate – Interconnect Offloading Versus Onloading

By Gilad Shainer, Mellanox

April 12, 2016

The high performance computing market is going through a technology transition – the Co-Design transition. As has already been discussed in many articles, this transition has emerged in order to solve the performance bottlenecks of today’s infrastructures and applications, performance bottlenecks that were created by multi-core CPUs and the existing CPU-centric system architecture.

How are multi-core CPUs the source for today’s performance bottlenecks? In order to understand that, we need to go back in time to the era of single-core CPUs. Back then, performance gains came from increases in CPU frequency and from the reduction of networking functions (network adapter and switches). Each new generation of product brought faster CPUs and lower-latency network adapters and switches, and that combination was the main performance factor. But this could not continue forever. The CPU frequency could not be increased any more due to power limitations, and instead of increasing the speed of the application process, we began using more CPU cores in parallel, thereby executing more processes at the same time. This enabled us to continue improving application performance, not by running faster, but by running more at the same time.

This new paradigm of increasing the amount of CPU cores dramatically increased the burden on the interconnect, and, moreover, changed the interconnect into the main performance enabler of the system. The key performance concern was how fast all the CPU processes could be synchronized and how fast data could be aggregated and distributed between them.

But the native interconnect latency has also reached the point of being exceedingly small compared to the overall communication patter. Today, InfiniBand switches runs at 90 nanosecond latency and InfiniBand adapters at 100 nanosecond latency. For CPU process communication frameworks, such as MPI collective communications, latency is in the range of tens of microseconds. Even if we continue to see reduction in the interconnect latency of another 10, 20, 40, or 50 nanoseconds, this is clearly negligible compared to the process communication latency. That means that the idea that has been suggested by certain companies to merge the network adapter with the CPU in order to reduce a few nanoseconds is certainly not the right thing for the future of HPC.

It is fair to ask whether this is relevant to the debate between offloading and onloading. The answer is that it is very relevant. In the past, the debate between offloading and onloading was mainly centered around CPU efficiency. An offloading interconnect technology was more complex to design and build, but in return, it offloaded the CPU from managing network activities, which could easily result in 40-50 percent better CPU and system utilization. The onloading interconnect technology is easier to build, but it is nothing more than a simple pipe, and all the network operations still must be managed and executed by the CPU; half of the CPU’s time is wasted from the point of the application. Furthermore, offloading enables technologies like RDMA, which cannot be done with an onloading approach. We have therefore witnessed numerous application performance examples that demonstrate the clear and dominant advantage of offloading solutions over onloading products (for example, DDR InfiniBand vs. Pathscale InfiniPath and QDR InfiniBand vs. QLogic/Intel TrueScale) [see i, ii, and iii].

Nowadays, the offloading architecture has become the critical element in overcoming performance bottlenecks, and it is not just a matter of performance and cost/performance comparisons. Systems cannot continue to scale unless intelligent interconnect and offloading are used.

As the number of processes continues to grow, one can increase the parallelism of solving the complex problems we deal with in science, research, and manufacturing. Therefore, the process communications become more and more critical. It is more than just the network latency of ping pong operations, but also the communication latency of complex, critical communications – collective operations or data aggregation operations. Executing these operations on the CPU/node has reach its performance limit and cannot be accelerated any further. The only solution is actually to perform these operations on the data while its moves within the cluster; that is, they are executed by the interconnect functions (switch, adapter) as the data moves. This approach, which was developed under the global architecture of Co-Design, will take us farther down the path toward exascale computing.

This technology trend will not affect only HPC, but rather will change the world of data analytics, machine learning, and other data-intensive applications and data search-based applications. The CPU core parallelism that saved the day in the mid-2000s has become the bottleneck today, and the new intelligent offloading interconnect solutions are the new saviors. Intelligent interconnect solutions are becoming the new co-processors, and they are therefore becoming a key factor for scalable computing.

Going back to basic application performance and system return on investment, it is expected that the comparison between EDR InfiniBand and Intel Omni-Path would be similar to the previous comparisons between the two different interconnect technology approaches. While only very small setups are available today, one can already see the system performance difference in various HPC application cases, for example WIEN2K, Quantum Espresso, and LS-DYNA.

WIEN2k allows users to perform electronic structure calculations of solids using density functional theory. It is an all-electron scheme including relativistic effects and has been licensed by more than 2000 user groups. Quantum Espresso is an integrated suite of Open Source computer codes for electronic structure calculations and materials modeling at the nanoscale. It is based on density functional theory, plane waves, and pseudopotentials. LS-DYNA is an advanced general-purpose multiphysics simulation software package developed by the Livermore Software Technology Corporation (LSTC). While the package continues to contain ever more possibilities for the calculation of complex, real world problems, its origins and core-competency lie in highly non-linear transient dynamic finite element analysis (FEA) using explicit time integration. LS-DYNA is used by the automotive, aerospace, construction, military, manufacturing, and bioengineering industries.

WIEN2K Performance comparison

Quantum ESPRESSO Performance comparison

LS-DYNA Performance comparison

In all three cases, we can see a clear performance advantage of the EDR InfiniBand smart network. It should be noted that the performance difference is of the entire system, ranging from 35% to 63% higher system performance with InfiniBand. It should also be noted that the system scale for these tests is small, and the gap will increase with system size.

Furthermore, as can be seen in the LS-DYNA case, for example, InfiniBand enables higher performance with only six nodes, versus Omni-Path on 12 nodes – InfiniBand delivers higher performance with half of the system size versus Omni-Path.

The system performance difference with smart offloading interconnect is clear, and the case of InfiniBand vs. Omni-Path is no different.

References

[i] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5613096&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5613096

[ii] http://www.dynalook.com/european-conf-2007/ls-dyna-performance-and-scalability-in-the-multi.pdf

[iii] http://www.eetimes.com/document.asp?doc_id=1278292&page_number=2

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!

Russian Supercomputer Employed to Develop COVID-19 Treatment

March 31, 2020

From Summit to [email protected], global supercomputing is continuing to mobilize against the coronavirus pandemic by crunching massive problems like epidemiology, therapeutic development and vaccine development. The latest a Read more…

By Staff report

What’s New in HPC Research: Supersonic Jets, Skin Modeling, Astrophysics & More

March 31, 2020

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

By Oliver Peckham

Pandemic ‘Wipes Out’ 2020 HPC Market Growth, Flat to 12% Drop Expected

March 31, 2020

As the world battles the still accelerating novel coronavirus, the HPC community has mounted a forceful response to the pandemic on many fronts. But these efforts won't inoculate the HPC industry from the economic effects of COVID-19. Market watcher Intersect360 Research has revised its 2020 forecast for HPC products and services, projecting... Read more…

By Tiffany Trader

LLNL Leverages Supercomputing to Identify COVID-19 Antibody Candidates

March 30, 2020

As COVID-19 sweeps the globe to devastating effect, supercomputers around the world are spinning up to fight back by working on diagnosis, epidemiology, treatment and vaccine development. Now, Lawrence Livermore National Read more…

By Staff report

Weather at Exascale: Load Balancing for Heterogeneous Systems

March 30, 2020

The first months of 2020 were dominated by weather and climate supercomputing news, with major announcements coming from the UK, the European Centre for Medium-Range Weather Forecasts and the U.S. National Oceanic and At Read more…

By Oliver Peckham

AWS Solution Channel

Amazon FSx for Lustre Update: Persistent Storage for Long-Term, High-Performance Workloads

Last year I wrote about Amazon FSx for Lustre and told you how our customers can use it to create pebibyte-scale, highly parallel POSIX-compliant file systems that serve thousands of simultaneous clients driving millions of IOPS (Input/Output Operations per Second) with sub-millisecond latency. Read more…

Q&A Part Two: ORNL’s Pooser on Progress in Quantum Communication

March 30, 2020

Quantum computing seems to get more than its fair share of attention compared to quantum communication. That’s despite the fact that quantum networking may be nearer to becoming a practical reality. In this second inst Read more…

By John Russell

Pandemic ‘Wipes Out’ 2020 HPC Market Growth, Flat to 12% Drop Expected

March 31, 2020

As the world battles the still accelerating novel coronavirus, the HPC community has mounted a forceful response to the pandemic on many fronts. But these efforts won't inoculate the HPC industry from the economic effects of COVID-19. Market watcher Intersect360 Research has revised its 2020 forecast for HPC products and services, projecting... Read more…

By Tiffany Trader

Weather at Exascale: Load Balancing for Heterogeneous Systems

March 30, 2020

The first months of 2020 were dominated by weather and climate supercomputing news, with major announcements coming from the UK, the European Centre for Medium- Read more…

By Oliver Peckham

Q&A Part Two: ORNL’s Pooser on Progress in Quantum Communication

March 30, 2020

Quantum computing seems to get more than its fair share of attention compared to quantum communication. That’s despite the fact that quantum networking may be Read more…

By John Russell

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

[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

Conversation: ANL’s Rick Stevens on DoE’s AI for Science Project

March 23, 2020

With release of the Department of Energy’s AI for Science report in late February, the effort to build a national AI program, modeled loosely on the U.S. Exascale Initiative, enters a new phase. Project leaders have already had early discussions with Congress... Read more…

By John Russell

Servers Headed to Junkyard Find 2nd Life Fighting Cancer in Clusters

March 20, 2020

Ottawa-based charitable organization Cancer Computer is on a mission to stamp out cancer and other life-threatening diseases, including coronavirus, by putting Read more…

By Tiffany Trader

Kubernetes and HPC Applications in Hybrid Cloud Environments – Part II

March 19, 2020

With the rise of cloud services, CIOs are recognizing that applications, middleware, and infrastructure running in various compute environments need a common management and operating model. Maintaining different application and middleware stacks on-premises and in cloud environments, by possibly using different specialized infrastructure and application... Read more…

By Daniel Gruber,Burak Yenier and Wolfgang Gentzsch, UberCloud

[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

Julia Programming’s Dramatic Rise in HPC and Elsewhere

January 14, 2020

Back in 2012 a paper by four computer scientists including Alan Edelman of MIT introduced Julia, A Fast Dynamic Language for Technical Computing. At the time, t Read more…

By John Russell

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

[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

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

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

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

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

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

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

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

IBM Unveils Latest Achievements in AI Hardware

December 13, 2019

“The increased capabilities of contemporary AI models provide unprecedented recognition accuracy, but often at the expense of larger computational and energet Read more…

By Oliver Peckham

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

IBM Debuts IC922 Power Server for AI Inferencing and Data Management

January 28, 2020

IBM today launched a Power9-based inference server – the IC922 – that features up to six Nvidia T4 GPUs, PCIe Gen 4 and OpenCAPI connectivity, and can accom Read more…

By John Russell

University of Stuttgart Inaugurates ‘Hawk’ Supercomputer

February 20, 2020

This week, the new “Hawk” supercomputer was inaugurated in a ceremony at the High-Performance Computing Center of the University of Stuttgart (HLRS). Offici Read more…

By Staff report

Summit Joins the Fight Against the Coronavirus

March 6, 2020

With the coronavirus sweeping the globe, tech conferences and supply chains are being hit hard – but now, tech is hitting back. Oak Ridge National Laboratory Read more…

By Staff report

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