parXXL : A Fine Grained Development Environment on Coarse Grained Architectures

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

2. 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 ParCeL-6 2 previous environments SSCRAP parXXL: A Fine Grained Development Environmenton Coarse Grained Architectures J. Gustedt , S. Vialle, A. De Vivo parXXL: Project overview Distributed server: fine grained simulations on coarse grained architecture Client machine: comfortable fine graineddevelopment environment

3. 32 1 1 1 1 1 1 1 1 • BSP relaxed • super-steps • Dynamic cell net • evolution • … Cell net computation Cell net creation Cell comm. Cell net evolution parXXL: A Fine Grained Development Environmenton Coarse Grained Architectures J. Gustedt , S. Vialle, A. De Vivo parXXL: Programming model Coarse grained parallelism Fine grained parallelism parXXL

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

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

6. 1PE parXXL: A Fine Grained Development Environmenton Coarse Grained Architectures J. Gustedt , S. Vialle, A. De Vivo parXXL: Optimized cell nets Basic cell net creations: • Basic user code: • Automatic load balancing • Neighbor cells are not grouped 1 PE 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

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

8. Exec time per cell & per cycle (s) Number of cells parXXL: A Fine Grained Development Environmenton Coarse Grained Architectures J. Gustedt , S. Vialle, A. De Vivo Relaxation perfs. on GdX machine 1 – Speed up fine grained simulations using more processors 2 – Extensibility: process larger problem on more processors with similar cost for each cell iteration Scales until 420 106 Cells on 310 PEs

9. parXXL: A Fine Grained Development Environmenton Coarse Grained Architectures J. Gustedt , S. Vialle, A. De Vivo 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 http://gforge.inria.fr/ before september 2006

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