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Professur Praktische Informatik
Projekte
Professur Praktische Informatik 


The T w o L Project

T w o L
Parallel programs realized within a mixed task and data parallel programming model can lead to a reduction of the communication overhead and can improve scalability properties. The TwoL project (Two-Level parallelism) aims at supporting the  application programmer to develop task and data parallel programs by providing a flexible interface allowing an efficient implementation on different parallel machines with distributed address space.
 
The specification provided by the programmer is organized in two well-separated levels (giving the model its name). The upper level describes the task parallel part, which allows multi-processor tasks to be executed sequentially or in parallel. The task level is fully hierarchical: any multi-processor task may introduce parallel tasks, even if it is already running in parallel with sibling tasks. The lower level consists of data parallel SPMD tasks. This results in a group-SPMD execution model at runtime.
 
Two different approaches are supported:
  1. a library-based approach in which the programmer specifies the exact task structure used for the execution at runtime;
  2. a compiler approach in which the final task structure is derived by a compiler tool using a series of transformation steps that are selected with the help of a suitable runtime prediction mechanism.