1. Cactus Workshop - NCSA Sep 27 - Oct 1 1999 Generic Cactus Workshop: Summary and Future Ed Seidel Albert Einstein Institute eseidel@aei-potsdam.mpg.de

2. Generic Cactus Workshop: Summary and Future n What have you learned? l What cactus is… –Try again: who can define it in a nutshell? Please tell me! –We hope it will be useful to many communities, from relativity to…to I/O research groups... l How to use it for your –Science, engineering –CS research l Portability on different parallel systems (try it this afternoon) –Without it, how would you run on an NT cluster, a T3E, an SGI, or even a combo? n We have tried to show you l A great set of tools for solving your problems, across many disciplines l Our view of where the future of computational science is going n Back to the wave equation: it was extra overhead to use Cactus compared to simple F77, but look at what you get!

3. Beyond the wave equation: Extra functionality Cactus provides NOW l Different parallel I/O layers that work wherever you run (relieving the nightmares…) –Checkpointing –Downsampling –Single/double –Portability across platforms –Choices of different systems l Parallelism on different architectures with different driver layers –PUGH unigrid driver –GrACE parallel dirver (with AMR) –Add something new l Elliptic solver technologies (parameters allow choices from many systems/methods) –PETSc –SOR –Other multigrid coming soon l Collaborative/community aspects l Metacomputing/scheduling tools it provides l AMR (almost…) l Visualisation tools (you can make beautiful movies, too)

4. How to add new functionality l Adding Driver layers l Adding interfaces to make it easier to configure a Cactus code –Module composition –Parameter inputs –Resource selection l Adding I/O layers l Adding AMR layers l Adding new elliptic solvers l Adding new physics modules l Adding performance monitoring tools (Autopilot) l Where do you want to go today?…

5. Cactus Computational Toolkit Science, Autopilot, AMR, Petsc, HDF, MPI, GrACE, Globus, Remote Steering... 1. User has science idea... Global Computational Grid: choose your PC, cluster, T3E, or string ‘em together... 3. Selects Appropriate Resources... 5. Collaborators log in to monitor... 4. Steers simulation, monitors performance... 2. Composes/Builds Code Components w/Interface... Looking Ahead at the Portal to Your Science: The Cactus Collaboratory

6. Summary n Lab to reinforce the lectures n Cactus Again, a new community code for 3D simulations l Portable toolkit/language for many PDE systems l Integration of many advanced tools l Collaborative infrastructure l Metacomputing for the general user: remote/distributed computing possible. n Tomorrow focus on Relativity n We hope we got you excited about some of these things...

7. Now, discuss l What do you think? l What you can do to help it move forward? l Afternoon lab (same rooms as yesterday): –I-Desk demo first in the NL lab –Test out parallelism of different machines, look at scaling –Test out elliptic solvers within Cactus –Try out thorn IsoSurfacer, thorn http –Try different I/O layers –Explore Viz tools... –Possibly see live demos of your thorns running in cactus... –Etc…have fun! –Pick up handouts at the table by the door! l Don’t forget, join us at Joe’s Brewery 8PM, 5th and Green l Please leave the comment forms on the table by the door!