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Communicator Info Assertion: No Underflow #487

Open mpiforumbot opened 8 years ago

mpiforumbot commented 8 years ago

Originally by jdinan on 2015-09-24 03:29:27 -0500

Motivation

This info key allows the programmer to assert that the length of messages received on the given communicator will be equal to the length of their corresponding receive buffers.

Without this assertion, a receiver does not know how much data will be sent. For large messages, the receiver is not able to determine ahead of time whether the sender will use an eager or rendezvous protocol.

Proposed Info Keys

The following text would be added to page 249, line 12 of MPI 3.0:

mpi_assert_no_underflow -- If set to true, the length of any received message on the
given communicator must be equal to the length of the corresponding receive buffer.

Related Tickets

mpiforumbot commented 8 years ago

Originally by jdinan on 2015-10-16 14:33:31 -0500

Sept. 2015 meeting -- name suggestion of mpi_assert_exact_length. Comment was that no_underflow suggests that overflow could be allowed (even though MPI forbids it).

mpiforumbot commented 8 years ago

Originally by jdinan on 2015-10-16 14:44:30 -0500

Sept. 2015 meeting -- Comment: should this be an info key or a new receive operation?

mpiforumbot commented 8 years ago

Originally by jdinan on 2015-10-16 14:45:25 -0500

We may want to restrict this to point-to-point communication to avoid impacting collectives.