1. Total Code Makeover Changing the Face of High Performance Code
Brian Foote
Wed., 18 May 2005
University of Illinois at Urbana-Champaign
11/10/2018
Total Code Makeover

2. A Roadmap
My Background, and Ralph Johnson’s UIUC Software Architecture Group
Objects, Frameworks, and HPC
Refactoring HPC Applications with Photran and Eclipse
11/10/2018
Total Code Makeover

3. An HPC Carpetbagger? An Old Fortran Hand Realtime Programming
Object-Oriented Frameworks
Reuse
Reflection
Software Evolution
Patterns
Software Architecture
High Performance Computing
11/10/2018
Total Code Makeover

4. The Gang of Four
Design Patterns: Elements of Reusable Object-Oriented Software
Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides
A landmark book that changed the way programmers think about building object-oriented programs
The essential field guide…
11/10/2018
Total Code Makeover

5. Patterns are Dispatches from the Trenches about What Works
Academics Feed the Novelty Vampires
Secrets are Important to Industry
11/10/2018
Total Code Makeover

6. A Scene from a Nightmare
11/10/2018
Total Code Makeover

7. Big Ball of Mud The de-facto standard software architecture
Why is the gap between what we preach and what we practice so large?
11/10/2018
Total Code Makeover

8. Sisyphus Revisited Writing variations of the same code becomes tedious
Libraries work well, but have their limitations
Object–Oriented Frameworks fill a void between libraries and applications
11/10/2018
Total Code Makeover

9. Frameworks
Abstract Classes and Components that together constitute a generic or template solution to problems in a particular domain
Do nothing well
Often exhibit an inversion of control; don’t call me, I’ll call you
Extend via inheritance; add fresh components
Well know in GUI World; others
Can take a long time to learn; should take a long time to build
11/10/2018
Total Code Makeover

10. Object-Oriented Frameworks
White-Box Frameworks use Inheritance
Black-Box Frameworks emphasize pluggable Components
A skeleton, or driver, or main loop calls your application-specific code
Polymorphism becomes the focus, not inheritance
11/10/2018
Total Code Makeover

11. Designing to Facilitate Change
Code evolves in an iterative, incremental fashion
Refactoring is the engine of the evolution
Mature code exhibits more black box reuse
Maturing code sports more patterns than immature code
11/10/2018
Total Code Makeover

12. Design of Scientific Applications (From Michael Frumkin http://wiki.cs.uiuc.edu/PatternsOfHPC)
Time represented as an outer loop
Iterations over time step
Space is represented by structured/unstructured grids
Important for understanding data locality
Data access patterns
Spatial parallelism
Physics is represented by an operator at each grid point
Data flow
Operator level of parallelism/dependence
11/10/2018
Total Code Makeover

13. The Last to be Shod Frameworks have been slow in coming to HPC
High Performance remains a craft; a cottage industry
Reuse and Performance often at odds
The Chasm: HPC People have been O-O Late Adopters
11/10/2018
Total Code Makeover

14. HPC: Programming Languages and Objects
FORTRAN (77, Carter era, James VI)
Fortran 90 (Bush the Elder, George II)
Fortran 2003 (Bush the Younger, George III)
ANSI C
C++
Matlab and Friends
Assembler?
11/10/2018
Total Code Makeover

15. The Imperial Vision You’ve seen one Grid; Mesh, you’ve seen ‘em all
Too hard for Physicists
Hotspots are in the Inner Loops, defy conventional SW abstraction approaches
11/10/2018
Total Code Makeover

16. Interoperatbility and Monoculture
Make them write it all in your favorite language
Interoperability is easy to achieve
Fortran / C / C++
You can build frameworks in C++
You can fake ‘em in C, with some effort
Fortran awaits F2K3 (.foo, .f00)
11/10/2018
Total Code Makeover

17. Hand Crafting Skilled Craftsmen Hand Tools Tedious and often Dangerous
Best way to achieve superior quality
We Live and Die in the Inner Loop
11/10/2018
Total Code Makeover

18. Macro Processing Use the C Preprocessor (cpp)
Even Fortran indulges this
Crude, but effective
Not easy to scale
11/10/2018
Total Code Makeover

19. Generative Approaches
Use a scripting language or preprocessor to generate code “glue”, or data
Use in lieu of of Macros
CCA, IBEAM
11/10/2018
Total Code Makeover

20. Languages and Patterns
X10
Chappel
Reflection and Metalevel Architectures (aka Aspects?)
What ever else I’ve forgotten
Patterns…
11/10/2018
Total Code Makeover

21. HPC Frameworks: Works in Progress
Frameworks have “succeeded” on a modest scale in HPC
Tension between performance and flexibility remains high
Message passing and sharing “concerns” still clutter the code
11/10/2018
Total Code Makeover

22. Refactoring Tools First developed at UIUC for Smalltalk
Made popular by Fowler, Kerievsky
Coming soon to a HPC near you
11/10/2018
Total Code Makeover

23. Refactoring “Behavior Preserving” code transformation Rename
Extract “method”
Verifies preconditions
Reconciles all occurrences
More reliable than cut ‘n’ paste, or search and replace
11/10/2018
Total Code Makeover

24. Photran: A Fortran Plugin For Eclipse

25. Photran History Opdyke’s C++ Tool
Refactory and the Refactoring Browser
IBM Eclipse Innovation Grant
IBM PERCS High Performance Computing Initiative
NASA IBEAM Project
CRefactory
11/10/2018
Total Code Makeover

26. Status: November 2004 Produced two MS Theses
Brought aboard two PhD Candidates
Repaired numerous parser bugs
Greatly Enhanced Stability
Implemented Outline Views
Make / Run / Debug under Linux
Polished the GUI
11/10/2018
Total Code Makeover

27. Status: May 2004 Hyperion Release (14 January 2005)
Parsed Full IBEAM Codebase
Support for g77, g95, debugging under Windows / Linux
Support for Lahey Fortran Windows
Eos (Eclipse 3.0.1) (4 February 2005)
11/10/2018
Total Code Makeover

28. Why Refactor Fortran Make code easier to understand
Make code easier to reuse
Improve structure
Banish duplication
Make code your own
Incrementally Cultivate the Code (XP)
Refactor to Components
Refactor to Patterns
11/10/2018
Total Code Makeover

29. What would you pay for a tools like this?
11/10/2018
Total Code Makeover

30. Something Wonderful
Tension between performance and flexibility is high
Moore and Amdahl are conspiring to help
Computational Science  Science
HP Computing  Computing
HPC Pioneers will lead the way
Pattern mining needs to begin now
11/10/2018
Total Code Makeover

31. Grid-Cogeneration Cycles too cheap to meter?
You are insatiable. I’ll sell you my Idle Process, at the going rate…
A Billion is an interesting #
11/10/2018
Total Code Makeover