The Once and Future SciDAC Thom H. Dunning, Jr. National Center for Supercomputing Applications and Department of Chemistry University of Illinois at Urbana-Champaign

The Once and Future SciDAC

Thom H. Dunning, Jr.National Center for Supercomputing Applications

and Department of ChemistryUniversity of Illinois at Urbana-Champaign

National Center for Supercomputing Applications

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

with apologies to T. H. White

University of Illinois at Urbana-Champaign


SciDAC: The Program

“Advances in the simulation of complex scientific and

engineering systems provide an unparalleled opportunity for solving major problems that face the nation in the

21st Century.”


SciDAC Goals

• Scientific Application Codes– Develop mathematical models, computational methods, and scientific

codes to take full advantage of the capabilities of terascale computers

• Computing Systems and Mathematical Software– Develop software infrastructure to accelerate the development of

scientific codes, achieve maximum efficiency on high-end computers, and enable a broad range scientists to use simulation in their research

• Collaboratory Software– Develop network technologies and collaboration tools to link

geographically separated researchers, to facilitate movement of large (petabyte) data sets, and to ensure that academic scientists can fully participate in these activities

Create a Scientific Computing Software Infrastructure that bridges the gap between applied mathematics & computer science and computational science in the physical, chemical, biological, and environmental sciences:


SciDAC Goals II

• Flagship Computing Facility– To provide computing resources to address a broad range of

scientific problems

• Topical Computing Facilities– To ensure that the most effective and efficient resources are used

to solve each class of problems

• Experimental Computing Facilities– To guide advances in computer technology to ensure that scientific

computing has the resources that it needs in the future

• ESNet– To support research in a connected world

Create a Scientific Computing Hardware Infrastructure that is robust, agile, and flexible:

SciDAC: Circa 2001

BES, BERFES, HENPASCR

HardwareInfrastructure Software Infrastructure

SCIENTIFIC

CODES

SI

MULATION

OPERATING

SYSTEM

Data Analysis &Visualization

Scientific DataManagement

Problem-solvingEnvironments

ProgrammingEnvironments

DATAGRIDS

COLLABORATORIES

MATHEMATICS

COMPUTING SYSTEMSSOFTWARE


SciDAC Score Card

Goal Status Comments

Scientific Challenge Codes

Excellent progress in selected areas, but many areas poorly supported or even neglected

Computing & Math Software

Excellent progress, but some areas need additional support

Collaboratory Software Good progress, but little used

Flagship Computing Facility

Two facilities established, NERSC and NLCF, but …

Topical Computing Facilities

QCDOC and MSCF, but many opportunities still unexplored

Experimental Computing Facilities

Little progress

After 5 YearsIs SciDAC Still Needed?

Yes!

After 5 Years Does SciDACNeed More Funding?

Yes!


Central Dogma

Hardware

Software

The central dogma of SciDAC is the close coupling between computer hardware and computer software

Changes in computer hardware requires changes, often major changes, in computer software. Responding to such changes in a timely manner requires a multidisciplinary approach.

PortingRevision

Rewriting

EnhancedPerformance(can be dramatic)

SciDACMultidisplinary Teams

The Coming Revolutionin Computing

“The Free Lunch Is Over: A Fundamental Turn Toward Concurrency in Software”

Herb Sutter in Dr. Dobb’s Journal 30(3), March 2005


The GHz Race

At the 2000 IEEE International Electron Devices Meeting, Intel announced that it expected to produce a 10 GHz microprocessor by 2005.

The fastest Intel microprocessor today runs at 3.8 GHz (Intel Pentium 4). It was introduced six months ago.

At its presentation of the 6XX series of Prescott, Intel stated that it is committed to “adding value beyond GHz.”


Increasing Computer Performance

• Increasing Clock Frequency– Pentium: 60 MHz to 3,800 MHz in 12 years

– Resulted in ~80% of performance increase


The Heat Problem

Courtesy of Bob Colwell

Increasing Frequency

Wat

ts/c

m2

1

10

100

1000

1.5 1.0 0.7 0.5 0.35 0.25 0.18 0.13 0.1 0.07

i386i486

PentiumPentium Pro

Pentium IIPentium III

Hot Plate

Nuclear Reactor

Rocket Nozzle

Pentium 4(Prescott)

Pentium 4(Willamette)


Managing the Heat Load

Liquid cooling system in Apple G5s

Heat sinks in 6XX series Pentium 4s


Leakage Current

From Minor Nuisance to Chip Killer

Dynamic Power

Leakage Power

300

250

200

150

100

50

0250 180 130 90 70

Dissipated Power ~ CV2f

Process Technology (nm)

Pow

er (

W)


Means of Increasing Performance

• Increasing Clock Frequency– From 60 MHz to 3,800 MHz in 12 years

– Has resulted in ~80% of performance increase

• Execution Optimization– More powerful instructions

– Execution optimization (pipelining, branch prediction, execution of multiple instructions, reordering instruction stream, etc.)


Microarchitecture Trends

Adapted from Johan De Gelas, Quest for More Processing Power,AnandTech, Feb. 8, 2005.

101

102

103

104

105

106

MIP

S

1980 1985 1990 1995 2000 2005 2010

Pentium ArchitectureSuper Scalar

Pentium Pro ArchitectureSpeculative Out-of-Order

Pentium 4 ArchitectureTrace Cache

Pentium 4 and Xeon Architecture with HTMulti-Threaded

Multi-Threaded, Multi-Core

Era ofInstructionParallelism

Era ofThread

Parallelism







• Larger Caches– On-chip caches to ameliorate the growing disparity

between processor speed and memory latency and bandwidth


Moore’s Law Still Holds

’60 ’65 ’70 ’75 ’80 ’85 ’90 ’95 ’00 ’05 ’10

Tra

nsi

stor

s P

er D

ie

1K4K 16K

64K256K

1M

16M4M

64M

4004

80808086

80286i386™

i486™Pentium®

MemoryMicroprocessor

Pentium® IIPentium® III

256M

Pentium® 4

Itanium®

1G2G4G

128M

Source: Intel

108

107

106

105

104

103

102

101

100

109

1010

1011

512M


Increasing Caches: Montecito







• Larger Caches– On-chip caches will continue to increase in size and

help mitigate disparities in computer subsystem performance


New Technologies for Computers

• Low power processors


IBM Blue Gene Systems

• LLNL BG/L– 360 teraflops– 64 racks

• 65,536 nodes• 131,072 processors

• Node– Two 2.8 Gflops processors

• System-on-a-Chip design• 700 MHz• Two fused multiply-adds per

cycle

– Up to 512 Mbytes of memory– 27 Watts


Technologies for Petascale Computers

• Low Power Processors– Need unprecedented application software scalability

• Application codes must scale to 100,000s of processors

– Need ability to recover from continual processor loss



• Low Power Processors– Need unprecedented scalability


– Need ability to recover from processor loss

• Multicore Chips


Architecture of Dual-Core Chips

• IBM Power5– Shared 1.92 Mbyte L2

cache

• AMD Opteron– Separate 1 Mbyte L2

caches– CPU0 and CPU1

communicate through the SRQ

• Intel Pentium 4– “Glued” two processors

together


Intel Processor Roadmap



• Low Power Processors– Need unprecedented scalability


– Need ability to recover from processor loss

• Multicore chips– Need to better understand a number of architectural

issues• Memory bandwidth

• Cache contention

• …


Other Promising Technologies

• Field Programmable Gate Arrays (FPGAs)– Capabilities increasing rapidly (riding silicon technology curve)

– Need efficient software development tools

• Heterogeneous Computer Systems– Different types of processors in single system

• Vector processors, superscalar processors, FPGAs

– High speed interconnect linking all processors

– May be especially advantageous for some applications, e.g., multiphysics applications

• Many Other New Ideas– DARPA: High Productivity Computing System program

– Universities: Sterling, Dally, …

SciDAC:Pathway to the Future

Questions?

Documents

The Once and Future SciDAC Thom H. Dunning, Jr. National Center for Supercomputing Applications and Department of Chemistry University of Illinois at Urbana-Champaign