University of Houston

So What’s Exascale Again?

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

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)

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

University of Houston

Compiler-Based Tools

Call Graph

Flow Graph

Array Regions

Dragon Analysis Tool

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

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

University of Houston

Runtime, Dynamic Tuning, Adaptation, …

Applications DRAGON

Static compilation module

High-endsystems

Performancemonitoring and abstraction

Dynamiccompilation

module

Architectural param

eters

Problem feedback

Executables

Instrumentation

Graphical interface

PerfSuite

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

University of Houston

Outlook