Situated @: Bath; Birkbeck; Cambridge; CCLRC Daresbury Reading The Royal Institution
Terascaling Applications on HPCx: The First 12 Months Mike Ashworth HPCx Terascaling Team HPCx...
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Transcript of Terascaling Applications on HPCx: The First 12 Months Mike Ashworth HPCx Terascaling Team HPCx...
Terascaling Applications on HPCx: The First 12 Months
Mike Ashworth
HPCx Terascaling TeamHPCx Service
CCLRC Daresbury Laboratory
UK
http://www.hpcx.ac.uk/
210th December 2003HPCx Annual Seminar
Outline
• Terascaling Objectives• Case Studies
– DL-POLY– CRYSTAL– CASTEP– AMBER– PFARM– PCHAN– POLCOMS
• Efficiency of Codes• Summary
Application, and notH/W driven
310th December 2003HPCx Annual Seminar
Terascaling Objectives
410th December 2003HPCx Annual Seminar
Terascaling Objectives
• The primary aim of the HPCx service is Capability Computing
• Key objective that user codes should scale to O(1000) cpus
• Largest part of our science support is the Terascaling Team
• Understanding performance and scaling of key codes
• Enabling world-leading calculations (demonstrators)
• Closely linked with Software Engineering Team and Applications Support Team
Jobs which use>= 50% of cpus
510th December 2003HPCx Annual Seminar
HPCx Terascaling
Team
Strategy for Capability Computing
• Performance Attributes of Key ApplicationsTrouble-shooting with Vampir & Paraver
• Scalability of Numerical AlgorithmsParallel eigensolvers. FFTs etc
• Optimisation of Communication Collectivese.g., MPI_ALLTOALLV and CASTEP
• New TechniquesMixed-mode programming
• Memory-driven Approachese.g., “In-core” SCF & DFT, direct minimisation & CRYSTAL
• Migration from replicated to distributed datae.g., DL_POLY3
• Scientific drivers amenable to Capability Computing- Enhanced Sampling Methods, Replica Methods
610th December 2003HPCx Annual Seminar
Case Studies
710th December 2003HPCx Annual Seminar
Molecular Simulation
DL_POLY W. Smith and T.R. Forester, CLRC Daresbury Laboratory
• General purpose molecular dynamics simulation package
http://www.cse.clrc.ac.uk/msi/software/DL_POLY/
810th December 2003HPCx Annual Seminar
DL_POLY3 Coulomb Energy Performance
Number of CPUs
DL_POLY3216,000 ions, 200 time steps, Cutoff=12Å
0
1
2
3
4
5
6
7
32 64 128 256
IBM SP/Regatta-H
AlphaServer SC ES45/1000 SGI Origin 3800/R14k-500
Performance Relative to the Cray T3E/1200E
• Distributed Data• SPME, with revised FFT Scheme
910th December 2003HPCx Annual Seminar
Measured Time (seconds)
Number of CPUs
Gramicidin in water;Gramicidin in water;rigid bonds + SHAKE:rigid bonds + SHAKE:792,960 ions, 50 time steps
0
0.5
1
1.5
2
2.5
32 64 128 256
IBM SP/Regatta-H
AlphaServer SC ES45/1000
Performance Relative to the SGI Origin 3800/R14k-500
749
312
176
115
396
200
11673
349
189
11477
0
200
400
600
800
32 64 128 256
SGI Origin 3800/R14k-500
AlphaServer SC ES45/1000
IBM SP/Regatta-H
Number of CPUs
DL_POLY3 Macromolecular Simulations
1010th December 2003HPCx Annual Seminar
Materials Science
CRYSTAL
• calculate wave-functions and properties of crystalline systems
• periodic Hartree-Fock or density functional Kohn-Sham Hamiltonian
• various hybrid approximations
http://www.cse.clrc.ac.uk/cmg/CRYSTAL/
1110th December 2003HPCx Annual Seminar
Crystal
• Electronic structure and related properties of periodic systems
• All electron, local Gaussian basis set, DFT and Hartree-Fock
• Under continuous development since 1974
• Distributed to over 500 sites world wide
• Developed jointly by Daresbury and the University of Turin
1210th December 2003HPCx Annual Seminar
Properties Energy Structure Vibrations (phonons) Elastic tensor Ferroelectric polarisation Piezoelectric constants X-ray structure factors Density of States / Bands Charge/Spin Densities Magnetic Coupling Electrostatics (V, E, EFG classical) Fermi contact (NMR) EMD (Compton, e-2e)
Crystal Functionality
• Basis Set– LCAO - Gaussians
• All electron or pseudopotential• Hamiltonian
– Hartree-Fock (UHF, RHF)– DFT (LSDA, GGA)– Hybrid funcs (B3LYP)
• Techniques– Replicated data parallel– Distributed data parallel
• Forces – Structural optimization
• Direct SCF• Visualisation
– AVS GUI (DLV)
1310th December 2003HPCx Annual Seminar
Benchmark Runs on Crambin
• Very small protein from Crambe Abyssinica - 1284 atoms per unit cell
• Initial studies using STO3G (3948 basis functions)
• Improved to 6-31G * * (12354 functions)
• All calculations Hartree-Fock
• As far as we know the largest Hartree-Fock calculation ever converged
1410th December 2003HPCx Annual Seminar
Scalability of CRYSTAL for crystalline Crambin
faster, more stable version of the parallel
Jacobi diagonalizer replaces ScaLaPack
HPCxvs.
SGI Origin
Increasing the basis set size increases the
scalability0
10
20
30
0 256 512 768 1024
Number of Processors
Pe
rfo
rma
nc
e (
arb
itra
ry)
Ideal
6-31G** IBM p690
6-31G IBM p690
STO-3G IBM p690
6-31G SGI Origin
STO-3G SGI Origin
1510th December 2003HPCx Annual Seminar
Crambin Results – Electrostatic Potential
• Charge density isosurface coloured according to potential• Useful to determine possible chemically active groups
1610th December 2003HPCx Annual Seminar
Futures - Rusticyanin
• Rusticyanin (Thiobacillus Ferrooxidans) has 6284 atoms (Crambin was 1284) and is involved in redox processes
• We have just started calculations using over 33000 basis functions
• In collaboration with S.Hasnain (DL) we want to calculate redox potentials for rusticyanin and associated mutants
1710th December 2003HPCx Annual Seminar
Materials Science
CASTEPCAmbridge Serial Total Energy Package
http://www.cse.clrc.ac.uk/cmg/NETWORKS/UKCP/
1810th December 2003HPCx Annual Seminar
What is Castep?
• First principles (DFT) materials simulation code– electronic energy – geometry optimization– surface interactions– vibrational spectra
• materials under pressure, chemical reactions
– molecular dynamics
• Method (direct minimization)– plane wave expansion of valence electrons– pseudopotentials for core electrons
1910th December 2003HPCx Annual Seminar
Castep 2003 HPCx performance gain
0
1000
2000
3000
4000
5000
6000
7000
8000
Job
tim
e
80 160 240 320
Total number of processors
Al2O3 120 atom cell, 5 k- points
Jan-03
Current 'Best'
Bottleneck:• Data Traffic in
3D FFT and MPI_AlltoAllV
2010th December 2003HPCx Annual Seminar
Castep 2003 HPCx performance gain
0
2000
4000
6000
8000
10000
12000
14000
16000
Job
Tim
e
128 256 512
Total number of processors
Al2O3 270 atom cell, 2 k- points
Jan-03
Current 'Best'
2110th December 2003HPCx Annual Seminar
Molecular Simulation
AMBER(Assisted Model Building with Energy Refinement)Weiner and Kollman, University of California, 1981
• Widely used suite of programs particularly for biomolecules
http://amber.scripps.edu/
2210th December 2003HPCx Annual Seminar
AMBER - Initial Scaling
0
2
4
6
8
10
12
0 32 64 96 128Number of Processors
Sp
ee
d-u
p
• Factor IX protein with Ca++ ions – 90906 atoms
2310th December 2003HPCx Annual Seminar
Current developments - AMBER
• Bob Duke– Developed a new version of Sander on HPCx– Originally called AMD (Amber Molecular Dynamics)– Renamed PMEMD (Particle Mesh Ewald Molecular Dynamics)
• Substantial rewrite of the code– Converted to Fortran90, removed multiple copies of
routines,…– Likely to be incorporated into AMBER8
• We are looking at optimising the collective communications – the reduction / scatter
2410th December 2003HPCx Annual Seminar
Optimisation – PMEMD
0
50
100
150
200
250
300
0 32 64 96 128 160 192 224 256Number of Processors
Tim
e (
se
co
nd
s)
PMEMD
Sander7
2510th December 2003HPCx Annual Seminar
Atomic and Molecular Physics
PFARMQueen’s University Belfast, CLRC Daresbury
Laboratory
• R-matrix formalism to treat applications such as the description of the edge region in Tokamak plasmas (fusion power research) and for the interpretation of astrophysical spectra
2710th December 2003HPCx Annual Seminar
Peigs vs. ScaLapack in PFARM
0
4000
8000
12000
16000
20000
0 64 128 192 256
Processors
Tim
e (
se
cs
)
Peigs total
ScaLapack total
Peigs diag
ScaLapack diag
Bottleneck:Matrix Diagonalisation
2810th December 2003HPCx Annual Seminar
ScaLapack diagonalisation on HPCx
0
50
100
150
200
250
300
0 64 128 192 256
Number of Processors
Tim
e (s
ecs)
Dim=7194,PDSYEV
Dim=7194,PDSYEVD
Dim=3888, PDSYEV
Dim=3888,PDSYEVD
2910th December 2003HPCx Annual Seminar
0
1000
2000
3000
4000
Tim
e (
se
cs
)
32 64 128 256
Number of Processors
Peigs
Scalapack D&C
Projected Sc'k
Stage 1 (Sector Diags) on HPCx
• Sector Hamiltonian matrix size 10032 (x 3 sectors)
3010th December 2003HPCx Annual Seminar
Computational Engineering
UK Turbulence ConsortiumLed by Prof. Neil Sandham, University of Southampton
• Focus on compute-intensive methods (Direct Numerical Simulation, Large Eddy Simulation, etc) for the simulation of turbulent flows
• Shock boundary layer interaction modelling - critical for accurate aerodynamic design but still poorly understood
http://www.afm.ses.soton.ac.uk/
3110th December 2003HPCx Annual Seminar
Direct Numerical Simulation: 3603 benchmark
0.0
10.0
20.0
30.0
40.0
0 128 256 384 512 640 768 896 1024Number of processors
Per
form
ance
(m
illi
on
ite
rati
on
po
ints
/sec
)
IBM Regatta (ORNL)
Cray T3E/1200E
IBM Regatta (HPCx)
Scaled from 128 CPUs
3210th December 2003HPCx Annual Seminar
Environmental Science
Proudman Oceanographic Laboratory Coastal Ocean
Modelling System (POLCOMS)
• Coupled marine ecosystem modelling
http://www.pol.ac.uk/home/research/polcoms/
3310th December 2003HPCx Annual Seminar
Coupled Marine Ecosystem Model
Physical Model
Pelagic Ecosystem Model
Benthic Model
Wind Stress
Heat FluxIrradiation
Cloud Cover
C, N, P, Si Sediments
oC
oC
River Inputs
OpenBoundary
3410th December 2003HPCx Annual Seminar
0
20
40
60
80
100
120
140
0 128 256 384 512 640 768 896 1024
Number of processors
Pe
rfo
rma
nc
e (
M g
rid
-po
ints
-tim
es
tep
s/s
ec
)
Ideal IBM
1 km IBM
2 km IBM
3 km IBM
6 km IBM
12 km IBM
POLCOMS resolution b/m : HPCx
3510th December 2003HPCx Annual Seminar
POLCOMS 2 km b/m : All systems
0
20
40
60
80
100
120
0 128 256 384 512 640 768 896 1024
Number of processors
Pe
rfo
rma
nc
e (
M g
rid
-po
ints
-tim
es
tep
s/s
ec
)
Ideal IBM
IBM p690
Cray T3E
Origin 3800
3610th December 2003HPCx Annual Seminar
Efficiency of Codes
3710th December 2003HPCx Annual Seminar
Motivation and Strategy
• Scalability of Terascale applications is only half the story• Absolute performance also depends on
single cpu performance• Percentage of peak is seen as an
important measure• Comparison with other systems e.g. vector machines
• Run representative test cases on small numbers of processors for applications and some important kernels
• Use IBM’s hpmlib to measure Mflop/s • Other hpmlib counters can help to understand
performancee.g. memory bandwidth, cache miss rates, FMA count, computational intensity etc.
Scientific output is the key measure
3810th December 2003HPCx Annual Seminar
Matrix-matrix multiply kernel
0
10
20
30
40
50
60
0 8 16 24 32
Number of processors
% o
f p
ea
k
3910th December 2003HPCx Annual Seminar
PCHAN small test case 1203
0
5
10
0 32 64 96 128
Number of processors
% o
f p
ea
k
0
500
1000
1500
Me
mo
ry b
an
dw
idth
(M
B/s
)
% of peak
Memory bandwidth
4010th December 2003HPCx Annual Seminar
Summary of percentage of peak
DLPOLY
PCHAN
AMBER
NAMD
CRYSTAL
GAMESS
H2MOL
CASTEP
PRMAT
DIAG
MXM
POLCOMS
0 10 20 30 40 50 60
% of peak
4110th December 2003HPCx Annual Seminar
• HPCx Terascaling Team– Mike Ashworth– Mark Bull– Ian Bush– Martyn Guest– Joachim Hein– David Henty
• IBM Technical Support– Luigi Brochard et al.
• CSAR Computing Service Cray T3E ‘turing’,Origin 3800 R12k-400 ‘green’
• ORNL IBM Regatta ‘cheetah’• SARA Origin 3800 R14k-500• PSC AlphaServer SC ES45-1000
Acknowledgements
– Adrian Jackson– Chris Johnson– Martin Plummer– Gavin Pringle– Lorna Smith– Kevin Stratford– Andrew Sunderland
4210th December 2003HPCx Annual Seminar
The Reality of Capability Computing on HPCx
•The success of the Terascaling strategy is shown by the Nov 2003 HPCx usage
•Capability jobs (512+ procs) account for 48% of usage
•Even without Teragyroid it is 40.7%8
0.2%161.9%
325.1%
647.3%
12815.8%
25621.4%
Capability48.0%
4310th December 2003HPCx Annual Seminar
Summary
• HPCx Terascaling team is addressing scalability for a wide range of codes
• Key Strategic Applications Areas– Atomic and Molecular Physics, Molecular Simulation, Materials
Science, Computational Engineering, Environmental Science
• Reflected by take up of Capability Computing on HPCx– In Nov ’03, >40% of time used by jobs with 512 procs and
greater
• Key challenges– Maintain progress with Terascaling– Include new applications and new science areas– Address efficiency issues esp. with single processor performance– Fully exploit the phase 2 system: 1.7 GHz p690+, 32 proc
partitions, Federation interconnect