1. GdX -
Grid eXplorer
parXXL: A Fine Grained Development Environment on Coarse Grained Architectures
PARA 2006 – UMEǺ
Jens Gustedt - Stéphane Vialle - Amelia De Vivo

2. parXXL: Project overview
IO data &
device control
Minimize (Tdev+∑Texec) ➔
Run very large simul. ➔
Speedup fine grained
simulations. ➔
Software suite
parXXL:
par::cellnet
par::cell
par::cntrl
par::mem
par::bench
par::sys
par::cpp
Client machine:
comfortable fine
grained development
environment
Distributed server:
fine grained
simulations on
coarse grained
architecture
ParCeL-6
SSCRAP
2 previous
environments
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

3. parXXL: Programming model1 32
Coarse grained
parallelism
Fine grained parallelism
parXXL
BSP relaxed
super-steps
Dynamic cell net
evolution …
Cell net
creation
Cell net computation
Cell comm.
Cell net evolution
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

4. parXXL: BSP level (SSCRAP)
SSCRAP: Programming environment
PRO model
BSP model
Relaxed
synchronization +
par::cntrl
Encapsulation
of data:
memory or file
Handle huge
data
par::mem::chunk
POSIX
standard
High
portability
par::sys
High
performances
MPI
Threads
2 optimized
runtimes
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

5. parXXL: Cellular level (ParCeL-6)
Cell Parameters
Cell Variables
A cell:
Cell input channels
Cell output channels
Cell external IO mechanisms
//Init function …
//Iter function
//Term function
User
code
Cyclic running
Dynamic cell net evolution
3 kinds of output channels
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

6. parXXL: Optimized cell nets
Basic cell net creations:
1 PE
Basic user code:
Automatic load balancing
Neighbor cells are not grouped
1 PE
Main function
1 PE
Ex: Cubic cell net
Optimized cell nets (par::cellnet)
Optimized user/par::cellnet code:
Explicit load balancing
Neighbor cells are grouped
1PE
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

7. parXXL: Process deployment
parXXL BSP level:
par::cntrl
par::mem
par::bench
par::sys
par::cpp
Worker
TCP-Client
Worker
TCP-Server
Worker
Worker
Cell behavior functions
User code including
par::cell operations
Cell net creation
Loop:
Cell net computation
Cell communications
Cell net update
Cell net delete
User code &
optimized par::cellnet code
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

8. Relaxation perfs. on GdX machine
1 – Speed up fine grained simulations
using more processors
Number of cells
Exec time
per cell &
per cycle
(s)
2 – Extensibility:
process larger
problem on more
processors with
similar cost for
each cell iteration
Scales until
Cells
on 310 PEs
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

9. parXXL: Conclusion & Perspectives
A framework to implement fine grained applications on coarse
grained architectures
January 2006: scales up to 310 PEs (relaxation benchmark)
Optimized runtimes for shm mainframes & for clusters
Future:
Implement global IO functions & Hybrid cell communications
Extend the cellular network library (par::cellnet)
Experiment on Grid5000 (French national Grid)
Application to optic & hot plasma simulations (ITER project)
Available on before september 2006
parXXL: A Fine Grained Development
Environment on Coarse Grained Architectures
J. Gustedt , S. Vialle,
A. De Vivo

10. parXXL: A Fine Grained Development Environment on Coarse Grained Architectures
Questions?