4.2 WRAPPER

A significant element of the software architecture utilized in MITgcm is a software superstructure and substructure collectively called the WRAPPER (Wrappable Application Parallel Programming Environment Resource). All numerical and support code in MITgcm is written to ``fit'' within the WRAPPER infrastructure. Writing code to ``fit'' within the WRAPPER means that coding has to follow certain, relatively straightforward, rules and conventions ( these are discussed further in section 4.3.1 ).

The approach taken by the WRAPPER is illustrated in figure 4.2 which shows how the WRAPPER serves to insulate code that fits within it from architectural differences between hardware platforms and operating systems. This allows numerical code to be easily retargetted.

Figure 4.2: Numerical code is written to fit within a software support infrastructure called WRAPPER. The WRAPPER is portable and can be specialized for a wide range of specific target hardware and programming environments, without impacting numerical code that fits within the WRAPPER. Codes that fit within the WRAPPER can generally be made to run as fast on a particular platform as codes specially optimized for that platform.

• 4.2.1 Target hardware
• 4.2.2 Supporting hardware neutrality
• 4.2.3 WRAPPER machine model
• 4.2.4 Machine model parallelism
  • 4.2.4.1 Tiles
  • 4.2.4.2 Tile layout
  
  
• 4.2.5 Communication mechanisms
• 4.2.6 Shared memory communication
  • 4.2.6.1 Memory consistency
  • 4.2.6.2 Cache effects and false sharing
  • 4.2.6.3 Operating system support for shared memory.
  
  
• 4.2.7 Distributed memory communication
• 4.2.8 Communication primitives
• 4.2.9 Memory architecture
• 4.2.10 Summary

Copyright © 2002 Massachusetts Institute of Technology