The Once And Future Scidac: Thom H. Dunning, Jr

The Once and Future SciDAC with apologies to T. H. White

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

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University of Illinois at Urbana-Champaign

National Center for Supercomputing Applications

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.”

National Center for Supercomputing Applications

SciDAC Goals 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:

•

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 National Center for Supercomputing Applications

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

•

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 National Center for Supercomputing Applications

SciDAC: Circa 2001 Hardware Infrastructure

Software Infrastructure

O P S E Y R S A T T E I M N G

C O L L A B O R A T O R I E S

D A T A G R I D S

ASCR

COMPUTING SYSTEMS SOFTWARE

Data Analysis & Visualization Programming Environments Scientific Data Management Problem-solving Environments

M A T H E M A T I C S

S C I E N T I F I C

S I M U L A T I O N

C O D E S

BES, BER FES, HENP

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

National Center for Supercomputing Applications

After 5 Years Is SciDAC Still Needed?

Yes!

After 5 Years Does SciDAC Need More Funding?

Yes!

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

Hardware Porting Revision Rewriting

SciDAC Enhanced Multidisplinary Teams Performance (can be dramatic)

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. National Center for Supercomputing Applications

The Coming Revolution in 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.” National Center for Supercomputing Applications

Increasing Computer Performance

•

Increasing Clock Frequency – Pentium: 60 MHz to 3,800 MHz in 12 years – Resulted in ~80% of performance increase

National Center for Supercomputing Applications

The Heat Problem Rocket Nozzle

1000

Watts/cm2

Nuclear Reactor

Pentium 4 (Prescott)

100

Pentium 4 (Willamette)

10

Hot Plate

Pentium Pro Pentium i486

i386

1 1.5µ

Pentium III Pentium II

1.0µ

0.7µ

0.5µ 0.35µ 0.25µ 0.18µ 0.13µ 0.1µ 0.07µ

Increasing Frequency Courtesy of Bob Colwell National Center for Supercomputing Applications

Managing the Heat Load

Liquid cooling system in Apple G5s

Heat sinks in 6XX series Pentium 4s

National Center for Supercomputing Applications

Leakage Current

From Minor Nuisance to Chip Killer Dissipated Power ~ CV2f

Power (W)

300 250 200

Dynamic Power

150

Leakage Power

100 50 0 250

180

130

90

70

Process Technology (nm)

National Center for Supercomputing Applications

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.)

National Center for Supercomputing Applications

Microarchitecture Trends

MIPS

106

Multi-Threaded, Multi-Core

105

Pentium 4 and Xeon Architecture with HT Multi-Threaded

104

Pentium 4 Architecture Trace Cache Pentium Pro Architecture Speculative Out-of-Order

103 102

Era of Instruction Parallelism

Pentium Architecture Super Scalar

101 1980

1985

1990

Era of Thread Parallelism

1995

2000

2005

2010

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

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.)

•

Larger Caches – On-chip caches to ameliorate the growing disparity between processor speed and memory latency and bandwidth National Center for Supercomputing Applications

Moore’s Law Still Holds 1011

2G 4G

Transistors Per Die

1010 Memory Microprocessor

109 108 107

4M

1M

6

10

64K 4K 16K

5

10

104

i486™ 80286

Pentium III Pentium® II Pentium®

i386™

8080

1K

103

256K

512M 1G 256M 128M Itanium® 64M Pentium® 4 16M ®

4004

8086

102 101 100

’60

’65

’70

’75

’80

’85

’90

’95

’00

’05

Source: Intel National Center for Supercomputing Applications

’10

Increasing Caches: Montecito

National Center for Supercomputing Applications

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.)

•

Larger Caches – On-chip caches will continue to increase in size and help mitigate disparities in computer subsystem performance National Center for Supercomputing Applications

New Technologies for Computers

•

Low power processors

National Center for Supercomputing Applications

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 National Center for Supercomputing Applications

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

National Center for Supercomputing Applications

New Technologies for Computers

•

Low Power Processors – Need unprecedented scalability • Application codes must scale to 100,000s of processors – Need ability to recover from processor loss

•

Multicore Chips

National Center for Supercomputing Applications

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 National Center for Supercomputing Applications

Intel Processor Roadmap

National Center for Supercomputing Applications

New Technologies for Computers

•

Low Power Processors – Need unprecedented scalability • Application codes must scale to 100,000s of processors – Need ability to recover from processor loss

•

Multicore chips – Need to better understand a number of architectural issues • Memory bandwidth • Cache contention •…

National Center for Supercomputing Applications

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, …

National Center for Supercomputing Applications

SciDAC: Pathway to the Future

Questions?