The problem

Redistribution Example

• Problem:
  Change the block size of a block-cyclic data distribution from r to kr.

  Example, k=2, P=3 processes, blocks.

  • initial block size is r elements
  • final block size is 2r elements

  

  MPI can create a general datatype consisting of r elements so blocks can be moved around as units.

  Note repeating communication after the first P*k blocks.