1. Results Matter. Trust NAG. Numerical Algorithms Group Mathematics and technology for optimized performance Alternative Processors Panel IDC, Tucson, Sept 10, 2008 Andrew Jones Vice-President HPC Business

2. Results Matter. Trust NAG. Outline 4 questions (posed by Robert) 4 observations 1 rant and a suggestion

3. Results Matter. Trust NAG. Panel Question 1 What is an alternative processor? requires the programmer to re-think code/structure promises large benefits for an acceptable amount of pain

4. Results Matter. Trust NAG. Panel Question 2 How should/can they be used to increase analysis throughput? Whatever you can make work :-)

5. Results Matter. Trust NAG. Panel Question 3 What language environment, new and/or old, should be used to take advantage of these alternative processors? Rule 1: Keep it Simple! (so both C and Fortran, with simple hooks or extensions) Rule 2: enable legacy code

6. Results Matter. Trust NAG. Panel Question 4 Should the user be involved with the specific programming of these processors? At first, they will have to be. We all hope over time less so.

7. Results Matter. Trust NAG. Observation 1 Accelerators or general purpose CPU’s? Even the general purpose processors have roadmaps that start to look more like accelerators in terms of programming aspects

8. Results Matter. Trust NAG. Observation 2 Technology advance “cannot escape pace and direction of change” John Shalf, NERSC Looking for the easy road will only lead to a detour and delay the inevitable

9. Results Matter. Trust NAG. Observation 3 Increasing parallelism in a node increasing compute power per unit of memory capacity increasing compute power per unit of memory performance

10. Results Matter. Trust NAG. Observation 3: Application Impact Increasing parallelism in a node decreasing memory capacity per unit of compute decreasing memory performance per unit of compute

11. Results Matter. Trust NAG. Observation 4 Where do accelerators help? Predicting whether the pain will deliver enough benefit before investing the effort is hard Don’t seem to help with hard problems (e.g. global, capability, etc)

12. Results Matter. Trust NAG. Rant: Why? Why does the HPC community cling to a culture of not paying for software? Applications, tools, data analysis,... Applications are the encapsulation of the science and have a long lifetime, so why do we treat them as the poor cousin of the hardware?

13. Results Matter. Trust NAG. You get what you measure Top 500

14. Results Matter. Trust NAG. You get what you measure dense linear algebra compute power

15. Results Matter. Trust NAG. Suggestion How about a ranking of problems solved? N million unknowns solved in x hours? It might be even easier to link this to science or business output than HPL TFLOPS

16. Results Matter. Trust NAG. Numerical Algorithms Group Mathematics and technology for optimized performance End