Up: Explicit Parallel I/O Previous: Parallel Data Transfer
The following restrictions allow for a simpler, more efficient
implementation of parallel I/O. We may either put them in the
language, or list them as recommended programming style.
- Items in the item list of a PREAD or PWRITE statements are
restricted to be variables (no io-implied-do). [Compilers may want
to relax this rule, by considering an io-implied-do as being an
operation that defines a new variable, akin to an array section,
with a distribution induced by the distribution of the variables
appearing in the implied-do-loop.]
- All values needed to determine which entities are specified by a
parallel I/O item list need be specified before the I/O statement.
That is, we prohibit a statement of the form PREAD (...) N,