Defining Scalable OS Requirements for Exascale and Beyond

By Robert W. Wisniewski, Chief Software Architect for Extreme Scale Computing, Intel

October 5, 2015

Over the past couple of decades two primary trends have driven system software for supercomputers to become significantly more complex. First, hardware has become more complex. Massive inter-node parallelism (100,000+ nodes), increasingly large intra-node parallelism (100+ hardware threads), wider vector units, accelerators, coprocessors, etc., have required that system software play a larger role in delivering the performance available from this new hardware. Second, applications have changed. Historically, extreme-scale high-performance computing (HPC) applications were stand-alone executables that were bulk synchronous, spatially and statically partitioned, and required minimal system services.

As the community moves towards exascale, applications are being integrated into workflows, require big data and analytics, are incorporating asynchronous capabilities, and demand an increasingly rich set of libraries, runtimes, and system services. As part of providing comprehensive system services, the compute node operating system is being integrated into the control system, which is sometimes referred to as the global operating system. While providing a complete set of system services is important, this article focuses on the challenges and needs of the Operating System (OS) on the compute node. Figure 1 shows the “left to right” model typical in HPC systems, the control system, and the node-local OS. We describe how these trends are changing the requirements and hence design of the HPC compute node OS, and describe promising directions for how these challenges will be met for exascale computing.

Wisniewski Figure1_9.29.15Background:
In addition to the above challenges, the compute node OS, hereafter just OS, must address an additional challenge. There has been a debate in the software community about whether a revolutionary or an evolutionary approach is needed to achieve exascale. We contend both are critical, and that the real challenge for system software to get to exascale and beyond is figuring out how to incorporate and support existing computation paradigms in an evolutionary manner while simultaneously supporting new revolutionary paradigms. The OS must provide this capability as well.

Historically, two designs have been used for operating systems. One is to start with a Full-Weight Kernel (FWK), typically Linux[i], and remove features so that it will scale up across more cores and out across a large cluster. Another approach is to start with a new, Light-Weight Kernel (LWK) and add functionality to provide a familiar API, typically Linux.

Linux, or more specifically the Linux API, including glibc and the Linux environment (/proc and /sys) is important for supporting the evolutionary aspect and for addressing the described complexity needs. There is a set of classical needs that are interrelated and must be met, including low noise, high performance, scalability for capability computing, and allowing user-space access to performance critical hardware, e.g., the network. There is a set of emerging needs that include the ability to handle asynchrony, manage power locally and globally, handle re- liability, provide for over commit of software threads, and interact effectively with runtimes. The classical needs allow applications to achieve high performance while the emerging needs provide for higher productivity and support of new programming and execution models.

A key requirement for an exascale OS kernel is nimbleness, the ability to be modified quickly and efficiently to support new hardware and to provide targeted capabilities for the HPC libraries, runtimes, and applications. This is opposite of the requirement for a general purpose OS, whose success is based on broad-based use with known interfaces. High-end HPC systems, those that will first achieve exascale and beyond, push the edge of technology out of necessity and introduce new hardware capabilities that need to be utilized effectively by high-end HPC software. As an example, a decade ago, large pages were integrated into CNK, Blue Gene’s LWK in about six months while large page support in major distributions of Linux took significantly longer and remains an on-going effort. The reason is CNK’s limited application domain allowed many simplifying assumptions. New hardware technology will be required to achieve exascale computing, and applications will need to aggressively exploit the new technology. Thus, what is needed, is an approach that while preserving the capability to support the existing interfaces (evolutionary) provides targeted and effective use of the new hardware (revolutionary) in a rapid and targeted manner (nimbleness).

The historical approaches of adding features to an LWK or trimming an FWK have additional weaknesses when trying to simultaneously support revolutionary and evolutionary models while trying to achieve high performance in an increasingly complex and rich environment. LWKs have been shown to exhibit low noise that allows high scalability. They also have been able to target the specific needs of HPC applications allowing higher performance. As the community moves to exascale, the need to leverage specific hardware and tailor the OS service to application needs, will become more important.

Three classes of approaches are emerging to overcome these weaknesses.

  1. The first is to continue to use Linux as the base and containers to limit the interference between multiple applications thereby allowing the different applications (often a classical HPC and an emerging one, e.g., analytics or visualization) to share a node’s resources while trying to minimize the effect on the classical HPC application. Containers provide a virtual environment in Linux that provide the appearance of isolated OS instances. In the Linux community there is considerable excitement and work involving containers and HPC may be able to leverage this broader base of activity. The challenge with the container approach is that Linux remains underneath and any fundamental challenge with Linux itself remains.
  1. The second approach is virtualization. A virtualized platform on which either an LWK or a Linux kernel can run provides high performance or the features of a more general purpose OS. It is important to ensure that the cost of virtualization, especially for the LWK, is kept to a bare minimum. This approach in isolation presents problems for simultaneous use of the LWK and FWK by the application, but could be combined with the approach below.
  1. The third approach is to run multiple kernels simultaneously on a node. This has been an area of intense effort in the last several years and many efforts including McKernel, FusedOS, Nix, Tesselation, Popcorn Linux, and mOS are exploring this path. We will describe mOS as an example. The vision is to run an LWK on the majority of the cores to achieve high performance and scalability, while running Linux on one or a small number of cores to provide Linux compatibility. From the application’s perspective it achieves the performance of an LWK but appears to be Linux.

Wisniewski. Figure2_9.29.15Figure 2 depicts the fully generalized mOS architecture for the research direction we are exploring in the multiple kernels space. While the figure depicts the full generality, we expect most instantiations to run a single application on a single LWK. A standard HPC Linux runs on a given core(s); an LWK(s )runs on the rest of the cores. On any given LWK, one or more applications may run. As mentioned, the expected scenario is to run Linux on one core, and one application on one LWK on the rest of the cores. When the application makes a system call, it is routed to the OS Node (via arrow 1b) if it is a file I/O operation, or to the LWK on the core that made the call (via arrow 1a). The LWK will handle performance critical calls. If it is a call that is not implemented by the LWK, then the LWK will transfer the call to Linux (via arrow 2) to be serviced. Linux will service the call and return to the LWK, which in turn returns back to user space on the original core. With this methodology, the application achieves the high performance and scalability offered by an LWK while providing the Linux environment. We have worked out an architecture for mOS and have early prototype code that is allowing us to confirm several of the architecture decisions we made.

System software for exascale systems is of necessity becoming more complex. The compute node OS, and how it supports the compute node runtimes and interacts with the global control system, will play a critical role in allowing us to achieve exascale and beyond. To be evolutionary and revolutionary simultaneously, the OS must meet the classical and emerging HPC requirements. A promising direction that several groups are exploring to address these needs is running multiple operating system kernels on a node simultaneously. While significant challenges remain and innovative work is still needed on the OS front there is confidence in being able to get the community well beyond exascale computing.

Author Bio:
Dr. Robert W. Wisniewski is an ACM Distinguished Scientist and the Chief Software Architect for Extreme Scale Computing and a Senior Principal Engineer at Intel Corporation. He has published over 60 papers in the area of high performance computing, computer systems, and system performance, and has filed over 50 patents. Before coming to Intel, he was the chief software architect for Blue Gene Research and manager of the Blue Gene and Exascale Research Software Team at the IBM T.J. Watson Research Facility, where he was an IBM Master Inventor and lead the software effort on Blue Gene/Q, which was the fastest machine in the world on the June 2012 Top 500 list, and occupied 4 of the top 10 positions. Prior to working on Blue Gene, he worked on the K42 Scalable Operating System project targeted at scalable next generation servers and the DARPA HPCS project on Continuous Program Optimization that utilizes integrated performance data to automatically improve application and system performance.  Before joining IBM Research, and after receiving a Ph.D. in Computer Science from the University of Rochester, Robert worked at Silicon Graphics on high-end parallel OS development, parallel real-time systems, and real-time performance monitoring.

[i] Linux® is the registered trademark of Linus Torvalds in the U.S. and other countries.

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!

AWS Expands Worldwide Availability to AMD-based Instances

July 22, 2019

Setting aside potential setbacks caused by U.S. trade policies, the steady cadence of AMD’s revival in HPC and the datacenter continued last week with AWS expanding availability of its AMD Epyc-based instances. Recall Read more…

By Staff

Microsoft Investing $1B in OpenAI Artificial General Intelligence R&D

July 22, 2019

Artificial general intelligence (AGI) is AI’s moonshot, the next giant leap for the AI field. Microsoft regards it to be feasible enough to warrant a $1 billion investment in OpenAI, the not-for-profit research organi Read more…

By Doug Black

Researchers Use Supercomputing to Study Links Between Hurricanes and Climate Change

July 19, 2019

As climate change looms, researchers are scrambling to answer the question of how a warming planet will affect the frequency and severity of already-deadly hurricanes. Now, a team of researchers from the University of Il Read more…

By Oliver Peckham

AWS Solution Channel

Unleashing Seismic Modeling at Scale: We Can’t Stop Quakes, But We Can Be Better Prepared

It has been a scary July so far for many residents of California. A magnitude 6.4 quake struck on July 4 near Ridgecrest (about 194 kilometers northeast of Los Angeles), followed by a magnitude 7.1 quake in the same region on July 5. Read more…

HPE Extreme Performance Solutions

Bring the Combined Power of HPC and AI to Your Business Transformation

A growing number of commercial businesses are implementing HPC solutions to derive actionable business insights, to run higher performance applications and to gain a competitive advantage. Read more…

IBM Accelerated Insights

Visual Capital: Seeing Digital Image and Video Archives as Potential Revenue Streams

As most business owners agree, cash is king. But what if there was a hidden source of revenue that companies are only starting to learn how to exploit? Read more…

San Diego Supercomputer Center to Welcome ‘Expanse’ Supercomputer in 2020

July 18, 2019

With a $10 million dollar award from the National Science Foundation, San Diego Supercomputer Center (SDSC) at the University of California San Diego is procuring a new supercomputer, called Expanse, to be deployed next Read more…

By Staff report

Microsoft Investing $1B in OpenAI Artificial General Intelligence R&D

July 22, 2019

Artificial general intelligence (AGI) is AI’s moonshot, the next giant leap for the AI field. Microsoft regards it to be feasible enough to warrant a $1 billi Read more…

By Doug Black

Informing Designs of Safer, More Efficient Aircraft with Exascale Computing

July 18, 2019

During the process of designing an aircraft, aeronautical engineers must perform predictive simulations to understand how airflow around the plane impacts fligh Read more…

By Rob Johnson

Intel Debuts Pohoiki Beach, Its 8M Neuron Neuromorphic Development System

July 17, 2019

Neuromorphic computing has received less fanfare of late than quantum computing whose mystery has captured public attention and which seems to have generated mo Read more…

By John Russell

Goonhilly Unveils New Immersion-Cooled Platform, Doubles Down on Sustainability Mission

July 16, 2019

Goonhilly Earth Station has opened its new datacenter – an enhancement to its existing tier 3 facility – in Cornwall, England, touting an ambitious commitme Read more…

By Oliver Peckham

ISC19 Cluster Competition: Application Results, Finally!

July 15, 2019

Our exhaustive coverage of the ISC19 Student Cluster Competition continues as we discuss the application scores below. While the scores were typically high, som Read more…

By Dan Olds

Nvidia Expands DGX-Ready AI Program to 19 Countries

July 11, 2019

Nvidia’s DGX-Ready Data Center Program, announced in January and designed to provide colo and public cloud-like options to access the company’s GPU-powered Read more…

By Doug Black

Argonne Team Makes Record Globus File Transfer

July 10, 2019

A team of scientists at Argonne National Laboratory has broken a data transfer record by moving a staggering 2.9 petabytes of data for a research project.  The data – from three large cosmological simulations – was generated and stored on the Summit supercomputer at the Oak Ridge Leadership Computing Facility (OLCF)... Read more…

By Oliver Peckham

Nvidia, Google Tie in Second MLPerf Training ‘At-Scale’ Round

July 10, 2019

Results for the second round of the AI benchmarking suite known as MLPerf were published today with Google Cloud and Nvidia each picking up three wins in the at Read more…

By Tiffany Trader

High Performance (Potato) Chips

May 5, 2006

In this article, we focus on how Procter & Gamble is using high performance computing to create some common, everyday supermarket products. Tom Lange, a 27-year veteran of the company, tells us how P&G models products, processes and production systems for the betterment of consumer package goods. Read more…

By Michael Feldman

Cray, AMD to Extend DOE’s Exascale Frontier

May 7, 2019

Cray and AMD are coming back to Oak Ridge National Laboratory to partner on the world’s largest and most expensive supercomputer. The Department of Energy’s Read more…

By Tiffany Trader

Graphene Surprises Again, This Time for Quantum Computing

May 8, 2019

Graphene is fascinating stuff with promise for use in a seeming endless number of applications. This month researchers from the University of Vienna and Institu Read more…

By John Russell

AMD Verifies Its Largest 7nm Chip Design in Ten Hours

June 5, 2019

AMD announced last week that its engineers had successfully executed the first physical verification of its largest 7nm chip design – in just ten hours. The AMD Radeon Instinct Vega20 – which boasts 13.2 billion transistors – was tested using a TSMC-certified Calibre nmDRC software platform from Mentor. Read more…

By Oliver Peckham

TSMC and Samsung Moving to 5nm; Whither Moore’s Law?

June 12, 2019

With reports that Taiwan Semiconductor Manufacturing Co. (TMSC) and Samsung are moving quickly to 5nm manufacturing, it’s a good time to again ponder whither goes the venerable Moore’s law. Shrinking feature size has of course been the primary hallmark of achieving Moore’s law... Read more…

By John Russell

Deep Learning Competitors Stalk Nvidia

May 14, 2019

There is no shortage of processing architectures emerging to accelerate deep learning workloads, with two more options emerging this week to challenge GPU leader Nvidia. First, Intel researchers claimed a new deep learning record for image classification on the ResNet-50 convolutional neural network. Separately, Israeli AI chip startup Read more…

By George Leopold

Nvidia Embraces Arm, Declares Intent to Accelerate All CPU Architectures

June 17, 2019

As the Top500 list was being announced at ISC in Frankfurt today with an upgraded petascale Arm supercomputer in the top third of the list, Nvidia announced its Read more…

By Tiffany Trader

Top500 Purely Petaflops; US Maintains Performance Lead

June 17, 2019

With the kick-off of the International Supercomputing Conference (ISC) in Frankfurt this morning, the 53rd Top500 list made its debut, and this one's for petafl Read more…

By Tiffany Trader

Leading Solution Providers

ISC 2019 Virtual Booth Video Tour


Intel Launches Cascade Lake Xeons with Up to 56 Cores

April 2, 2019

At Intel's Data-Centric Innovation Day in San Francisco (April 2), the company unveiled its second-generation Xeon Scalable (Cascade Lake) family and debuted it Read more…

By Tiffany Trader

Cray – and the Cray Brand – to Be Positioned at Tip of HPE’s HPC Spear

May 22, 2019

More so than with most acquisitions of this kind, HPE’s purchase of Cray for $1.3 billion, announced last week, seems to have elements of that overused, often Read more…

By Doug Black and Tiffany Trader

A Behind-the-Scenes Look at the Hardware That Powered the Black Hole Image

June 24, 2019

Two months ago, the first-ever image of a black hole took the internet by storm. A team of scientists took years to produce and verify the striking image – an Read more…

By Oliver Peckham

Announcing four new HPC capabilities in Google Cloud Platform

April 15, 2019

When you’re running compute-bound or memory-bound applications for high performance computing or large, data-dependent machine learning training workloads on Read more…

By Wyatt Gorman, HPC Specialist, Google Cloud; Brad Calder, VP of Engineering, Google Cloud; Bart Sano, VP of Platforms, Google Cloud

Chinese Company Sugon Placed on US ‘Entity List’ After Strong Showing at International Supercomputing Conference

June 26, 2019

After more than a decade of advancing its supercomputing prowess, operating the world’s most powerful supercomputer from June 2013 to June 2018, China is keep Read more…

By Tiffany Trader

In Wake of Nvidia-Mellanox: Xilinx to Acquire Solarflare

April 25, 2019

With echoes of Nvidia’s recent acquisition of Mellanox, FPGA maker Xilinx has announced a definitive agreement to acquire Solarflare Communications, provider Read more…

By Doug Black

Qualcomm Invests in RISC-V Startup SiFive

June 7, 2019

Investors are zeroing in on the open standard RISC-V instruction set architecture and the processor intellectual property being developed by a batch of high-flying chip startups. Last fall, Esperanto Technologies announced a $58 million funding round. Read more…

By George Leopold

Nvidia Claims 6000x Speed-Up for Stock Trading Backtest Benchmark

May 13, 2019

A stock trading backtesting algorithm used by hedge funds to simulate trading variants has received a massive, GPU-based performance boost, according to Nvidia, Read more…

By Doug Black

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