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Next: FORALL-ELSEFORALL construct Up: Explicit Parallel I/O Previous: Restrictions

Extensions

• We may want to write an array with a layout that is suited to the mapping of the array that will appear in the input item list, rather than suited to the mapping of the array in the output list. To achieve this, we need to add align/distribute information as part of the PWRITE statement.
• We may want a REMAP statement, to be used instead of the sequence CLOSE ... OPEN, in order to associate a new mapping to an existing file.
• We may want to extend the INQUIRE statement to return file mapping information. Alternatively, we may use the same query intrinsics used to query array partitions.
• A new intrinsic function of the form INDEX(filemap-name, list-of-indices) would be handy, in order to address random-access files as multi-dimensional arrays. E.g.

  READ (7, REC = INDEX(F1,3,5) ) A

• Each data transfer operation specifies an association between parts of the file and abstract processor nodes where from (where to) the data in the record is transferred. We may want to add additional directives to the OPEN statement to indicate that this association fulfills certain restrictions for as long as the file is open.
  • Accesses to a file are independent if, in all data transfers, each file part is associated with the same processor node. An INDEPENDENT argument in the OPEN statement may be used to specify this condition (which simplifies file caching).
  • A data transfer is aligned if each file part is associated with a unique processor node (is not split among two processor nodes). We may use an ALIGNED argument in the OPEN statement to specify that all data transfers are aligned. (INDEPENDENT implies ALIGNED, but not vice versa).