Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Bug repellent for supercomputers proves effective

15.11.2012
Lawrence Livermore National Laboratory (LLNL) researchers have used the Stack Trace Analysis Tool (STAT), a highly scalable, lightweight tool to debug a program running more than one million MPI processes on the IBM Blue Gene/Q (BGQ)-based Sequoia supercomputer.

The debugging tool is a significant milestone in LLNL's multi-year collaboration with the University of Wisconsin (UW), Madison and the University of New Mexico (UNM) to ensure supercomputers run more efficiently.

Playing a significant role in scaling up the Sequoia supercomputer, STAT, a 2011 R&D 100 Award winner, has helped both early access users and system integrators quickly isolate a wide range of errors, including particularly perplexing issues that only manifested at extremely large scales up to 1,179,648 compute cores. During the Sequoia scale-up, bugs in applications as well as defects in system software and hardware have manifested themselves as failures in applications. It is important to quickly diagnose errors so they can be reported to experts who can analyze them in detail and ultimately solve the problem.

"STAT has been indispensable in this capacity, helping the multi-disciplined integration team keep pace with the aggressive system scale-up schedule," said LLNL computer scientist Greg Lee.

"While testing a subsystem of Blue/Gene Q, my test program consistently failed only when scaled to 1,179,648 MPI processes. Although the test program was simple, the sheer scale at which this program ran made debugging efforts highly challenging. But when I applied STAT, it quickly revealed that one particular rank process was consistently stuck in a system call," said Dong Ahn, a computer scientist in Livermore Computing.

Based on this finding, a system expert took a close look at the compute core on which this rank process was running and discovered a hardware defect. "Replacing the component suddenly got the entire Sequoia system back to life," Ahn said. "Putting this exercise into perspective, this error was due to a defect in a tiny hardware unit, the decrementor, of a single hardware thread out of a total of 4.7 million hardware threads. I felt it was like finding a needle in a haystack over a coffee break."

Sequoia delivers 20 petaflops of peak power and was ranked No. 1 in June of this year's TOP500 list. It is currently ranked No. 2, behind Oak Ridge National Laboratory's Titan.

LLNL plans to use Sequoia's impressive computational capability to advance understanding of fundamental physics and engineering questions that arise in the National Nuclear Security Administration's (NNSA) program to ensure the safety, security and effectiveness of the United States' nuclear deterrent without testing. Sequoia also will support NNSA/DOE programs at LLNL that focus on nonproliferation, counterterrorism, energy, security, health and climate change.

As LLNL takes delivery of the Sequoia system and works to move it into production, computer scientists will migrate applications that have been running on earlier systems to this newer architecture. This is a period of intense activity for LLNL's application teams as they gain experience with the new hardware and software environment.

"Having a highly effective debugging tool that scales to the full system is vital to the installation and acceptance process for Sequoia. It is critical that our development teams have a comprehensive parallel debugging tool set as they iron out the inevitable issues that come up with running on a new system like Sequoia," said Kim Cupps, leader of the Livermore Computing Division at LLNL.

STAT is particularly important for LLNL because supercomputer simulations are essential in virtually every mission area of the Laboratory. The tool also has been used at other sites and proved to be effective on a wide range of supercomputer platforms, including Linux clusters and Cray systems.

The team is actively pursuing further optimization of STAT technologies and is exploring commercialization strategies. More information about STAT, including a link to the source code, is available on the Web.

More Information
STAT
ASC Sequoia
Early science runs prepare Lawrence Livermore National Lab's Sequoia for national security missions

LLNL news release, Nov. 9, 2012

"Venturing into the heart of high-performance computing simulations"
Science & Technology Review, September 2012
Founded in 1952, Lawrence Livermore National Laboratory provides solutions to our nation's most important national security challenges through innovative science, engineering and technology. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.

Anne Stark | EurekAlert!
Further information:
http://www.llnl.gov

More articles from Information Technology:

nachricht Superfast fluorescence sets new speed record
27.07.2015 | Duke University

nachricht Two crystals are better than one
22.07.2015 | The Agency for Science, Technology and Research (A*STAR)

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Gefangen in Ruhelosigkeit

Mit ultrakalten Atomen lässt sich ein neuer Materiezustand beobachten, in dem das System nicht ins thermische Gleichgewicht kommt.

Was passiert, wenn man kaltes und heißes Wasser mischt? Nach einer Weile ist das Wasser lauwarm – das System hat ein neues thermisches Gleichgewicht erreicht....

Im Focus: Quantum Matter Stuck in Unrest

Using ultracold atoms trapped in light crystals, scientists from the MPQ, LMU, and the Weizmann Institute observe a novel state of matter that never thermalizes.

What happens if one mixes cold and hot water? After some initial dynamics, one is left with lukewarm water—the system has thermalized to a new thermal...

Im Focus: Superschneller Wellenritt im Kristall: Elektronik auf Zeitskala einzelner Lichtschwingungen möglich

Physikern der Universitäten Regensburg und Marburg ist es gelungen, die von einem starken Lichtfeld getriebene Bewegung von Elektronen in einem Halbleiter in extremer Zeitlupe zu beobachten. Dabei konnten sie ein grundlegend neues Quantenphänomen entschlüsseln. Die Ergebnisse der Wissenschaftler sind jetzt in der renommierten Fachzeitschrift „Nature“ veröffentlicht worden (DOI: 10.1038/nature14652).

Die rasante Entwicklung in der Elektronik mit Taktraten bis in den Gigahertz-Bereich hat unser Alltagsleben revolutioniert. Sie stellt jedoch auch Forscher...

Im Focus: On the crest of the wave: Electronics on a time scale shorter than a cycle of light

Physicists from Regensburg and Marburg, Germany have succeeded in taking a slow-motion movie of speeding electrons in a solid driven by a strong light wave. In the process, they have unraveled a novel quantum phenomenon, which will be reported in the forthcoming edition of Nature.

The advent of ever faster electronics featuring clock rates up to the multiple-gigahertz range has revolutionized our day-to-day life. Researchers and...

Im Focus: Erster Nachweis von Lithium in einem explodierenden Stern

Erstmals konnte das chemische Element Lithium in der ausgestoßenen Materie einer Nova nachgewiesen werden. Beobachtungen von Nova Centauri 2013 mit Teleskopen des La Silla-Observatoriums der ESO und in der Nähe von Santiago de Chile helfen bei der Aufklärung des Rätsels, warum so viele junge Sterne mehr von diesem Element enthalten als erwartet. Diese Entdeckung liefert ein seit langem fehlendes Teil im Puzzle der chemischen Entwicklungsgeschichte unserer Galaxie und ist ein großer Fortschritt für das Verständnis des Mischungsverhältnisses der chemischen Elemente in den Sternen unserer Milchstraße.

Das leichte chemische Element Lithium ist eines der wenigen Elemente, das nach unserer Modellvorstellung auch beim Urknall vor 13,8 Milliarden Jahren...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Türme und Maste aus Stahl – Neues aus Forschung und Anwendung

31.07.2015 | Veranstaltungen

Tagung „Brandschutz im Tank- und Gefahrgutlager“ am 16. November 2015 im Essener Haus der Technik stellt praktische Lösungen vor

30.07.2015 | Veranstaltungen

12. BMBF-Forum für Nachhaltigkeit: Green Economy, Energiewende und die Zukunft der Städte

30.07.2015 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Wiederaufladbare Batterien machen sich breit

31.07.2015 | Seminare Workshops

Alles zur Kryotechnik: HDT bietet Seminar zum „Kryostatbau“ an

31.07.2015 | Seminare Workshops

Erster Zug von Siemens für Thameslink‑Strecke in UK angekommen

31.07.2015 | Verkehr Logistik