RealityGrid: ESLEA Task E2
Robin Pinning
University of Manchester
ESLEA Technical Collaboration Mtg.
20 June 2006, NeSC
Overview
• RealityGrid Projects
– TeraGyroid
– SPICE
– MPICH-G2 based Applications
•
•
•
•
NAMD Performance Profiling
Port Forwarding
MPICH-G2
Future Work
RealityGrid projects
• TeraGyroid
– TeraGyroid project coupling HPC (LB3D), HPV, high
performance networks and Grid-infrastructure
– Network focus on high bandwidth links
• SPICE
– SPICE project coupling HPC (NAMD), Vis., high quality
networks and Grid-infrastructure
– Network focus on high quality, dedicated, low latency links
• MPICH-G2 based LB3D/LAMMPS
– Nektar and Vortonics used MPICH-G2 during SPICE
demos, now extended to LB3D/LAMMPS simulations
– Network focus on high bandwidth and low latency links
RealityGrid Architecture
SPICE
Simulation
Steering library
VRPN
Haptic
g
r in e s
e
e
g
St ssa II)
me ASC
(
Data
transfer
(binary)
Client
Steering library
Steering library
Visualization
IMD
Performance Profiling
• Investigate how differing network characteristics affect the
performance of an instrumented interactive NAMD job
• Define performance as ‘wall time per simulation timestep’
• NAMD simulation sends simulation state over network to VMD
client for visualisation and monitoring
• Latency sensitive as simulation is stalled during send to VMD
• Nistnet used to vary latency, bandwidth and introduce packet
loss to simulate congestion
Newton
(NAMD)
UKLight
Dual-homed
Linux PC
(Nistnet)
Pt-to-pt
GigE
Workstation
(VMD)
Port Forwarding
• Hidden node problem on many HPC resources
• Head node connected to internet but back end nodes are only
connected to head node and each other (on internal network).
Port forwarding needed
• Modified Dante package used on HPCx
N ode 1
N ode 2
Internet
Head N ode
N ode 3
N ode 4
MPICH-G2
• MPICH-G2 is a grid-enabled MPI implementation
• Uses vendor-MPI for intramachine communications and TCP
for intermachine
• Due to inevitable latency of going off machine, best suited to
inherently distributed applications
• Useful if your problem is too large for one machine
• Nektar and Vortonics applications demoed during SC05 used
MPICH-G2 partly across UKLight
• Plans to use MPICH-G2 based versions of LAMMPS and
LB3D
Future Work
• Deployment of MPICH-G2 based codes
• Profiling of MPICH-G2 based code
performance
• Use of Application Hosting Environment
with these codes
• Testing and deployment of Clive’s network
reservation work