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 A New Kind of Wood Chip: Collaboration Could Yield Biodegradable Computer Chips
28.05.2015 | University of Wisconsin-Madison

nachricht New transregional special research field at the universities of Stuttgart and Constance
28.05.2015 | Universität Stuttgart

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Galapagos-Vulkanismus: Überraschend explosiv

Internationales Vulkanologen-Team präsentiert neue Erkenntnisse zur Eruptions-Geschichte

Vor 8 bis 16 Millionen Jahren gab es im Gebiet der heutigen Galapagos-Inseln einen hochexplosiven Vulkanismus. Das zeigt erstmals die Auswertung von...

Im Focus: Lasers are the key to mastering challenges in lightweight construction

Many joining and cutting processes are possible only with lasers. New technologies make it possible to manufacture metal components with hollow structures that are significantly lighter and yet just as stable as solid components. In addition, lasers can be used to combine various lightweight construction materials and steels with each other. The Fraunhofer Institute for Laser Technology ILT in Aachen is presenting a range of such solutions at the LASER World of Photonics trade fair from June 22 to 25, 2015 in Munich, Germany, (Hall A3, Stand 121).

Lightweight construction materials are popular: aluminum is used in the bodywork of cars, for example, and aircraft fuselages already consist in large part of...

Im Focus: Wie Solarzellen helfen, Knochenbrüche zu finden

FAU-Forscher verwenden neues Material für Röntgendetektoren

Nicht um Sonnenlicht geht es ihnen, sondern um Röntgenstrahlen: Wissenschaftler der Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) haben zusammen mit...

Im Focus: Festkörper-Photonik ermöglicht extrem kurzwellige UV-Strahlung

Mit ultrakurzen Laserpulsen haben Wissenschaftler aus dem Labor für Attosekundenphysik in dünnen dielektrischen Schichten EUV-Strahlung erzeugt und die zugrunde liegenden Mechanismen untersucht.

Das Jahr 1961, die Erfindung des Lasers lag erst kurz zurück, markierte den Beginn der nichtlinearen Optik und Photonik. Denn erstmals war es Wissenschaftlern...

Im Focus: Solid-state photonics goes extreme ultraviolet

Using ultrashort laser pulses, scientists in Max Planck Institute of Quantum Optics have demonstrated the emission of extreme ultraviolet radiation from thin dielectric films and have investigated the underlying mechanisms.

In 1961, only shortly after the invention of the first laser, scientists exposed silicon dioxide crystals (also known as quartz) to an intense ruby laser to...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

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

Cannabis – eine andauernde Kontroverse

29.05.2015 | Veranstaltungen

Frauen können nicht alles haben - Männer aber schon?!

29.05.2015 | Veranstaltungen

13. Koblenzer eLearning Tage

28.05.2015 | Veranstaltungen

 
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Galapagos-Vulkanismus: Überraschend explosiv

29.05.2015 | Geowissenschaften

"Drittes Auge": Hightech-Einkaufshilfe für Blinde

29.05.2015 | Innovative Produkte

Brüchiges Erbgut: Neuer Therapie-Ansatz gegen Speiseröhrenkrebs

29.05.2015 | Biowissenschaften Chemie