Re: proposal of Thakur
Rajeev Thakur (thakur@mcs.anl.gov)
Sun, 2 Feb 1997 17:08:39 -0600
> The problem is not test_fn vs wait_fn. The problem is that a user call to
> MPI_WAIT may block the MPI process in some implementations and may put it
> in a polling cycle in other implementations. The user does not know (now)
> which is which. We would need to specify two possible behaviors for
> MPI_WAIT, one where the user callback is repeatedly invoked, and one where
> it is OK to call a blocking callback within MPI_WAIT. We would need to
> restrict implementations so that it is OK for the user to block in
> MPI_WAIT. We would need to provide a mechanism fo the user to find out
> which implemtation is used on the system it runs. It's even uglier at
> second glance
My point was that the user provides a test_fn and a wait_fn and
doesn't care which function is used by the MPI implementation within
MPI_Wait. We can specify that it is up to the implementation to decide
whether to use test_fn or wait_fn, depending on whether it chooses to
poll or block in MPI_Wait.
The user need not know which function was used; the only thing he is
guaranteed is that MPI_Wait will return after the request has
completed.
Rajeev