[MPI3-IO] New MPI-IO routines

[Mohamad Chaarawi]

Hi all,

We would like to get a discussion going on adding new routines to the 
standard that would support non-blocking but ordered access routines, 
and non-blocking ordered file manipulation routines. They would be two 
separate tickets but they share similar semantics.

So basically what we would like is that when we call:
1) iwrite_at()
2) iread_at()
3) iwrite_at()
...
4) waitall()

We would like to see the data accessed as if the calls were blocking. 
This could translate to something like:
iwrite_at()
iwait()
iread_at()
iwait()
iwrite_at()
iwait()

There is ofcourse no such thing as iwait, but you get the idea :-)

Our use case for this is the SWMR functionality that is being worked on, 
where the non-blocking version would require the MPI library to remember 
the order in which the operations were called; otherwise I don't see how 
we can enforce this ordering and at the same time keep the entire I/O 
access nonblocking.
We probably need to rename the routines (something other than the i 
prefix) because the semantics are different from the current 
non-blocking routines. Maybe aread/awrite (a for asynchronous).

Another feature we are considering is the non-blocking file manipulation 
routines. Similarly to the semantics described above, the library needs 
to remember the order they are called.
iopen
iset_view
iwrite
iclose
...
waitall()

Again since the semantics are different in the way other immediate 
routines are defined, we need to reconsider the naming.

Any thoughts?

Thanks,
Mohamad