1. University of Houston So What’s Exascale Again?

2. University of Houston The Architects Did Their Best… Scale of parallelism Multiple kinds of parallelism in HW Too little memory Data transfer too slow It’s going to take a while to sort this out… And this is the result

3. University of Houston Compilers We implement Fortran, C and C++ We provide OpenMP, CUDA, UPC, CAF, accelerator directives We could add more: –Languages (would you use them?) –Enhancements to existing languages and directives –Assertions (assertions of facts) –Annotations (new kinds of control)

4. University of Houston Compiler-Based Tools Provide more information to application developer Perform “clerical” tasks Help relate information (e.g. performance data) to source Pass information to runtime Generate information and pass it to runtime (e.g. to support scheduling) Help collect performance data BT NAS Benchmark

5. University of Houston Compiler-Based Tools Call Graph Flow Graph Array Regions Dragon Analysis Tool

6. University of Houston Compilers The best thing since sliced bread A few minor limitations –Can’t reconfigure the hardware if the hardware is not reconfigurable But… don’t like to guess about what you are trying to do –So only work with information you gave them –Or obtained via a tool or the runtime –Require heavy investment –Compiler-based tools very powerful

7. University of Houston Why Isn’t It Business as Usual? Heterogeneity in our systems Scale of parallelism Too many kinds of parallelism in HW Too little memory Data transfer too slow

8. University of Houston Runtime, Dynamic Tuning, Adaptation, … Applications DRAGON Static compilation module High-end systems Performance monitoring and abstraction Dynamic compilation module Architectural parameters Problem feedback Executables Instrumentation Graphical interfac e PerfSui te workload Editing, OMP insertion Open64 KOJAK Compilers, their runtime systems and dynamic (re)optimizers can be a very powerful infrastructure for translating and adapting code

9. University of Houston Outlook