[Mpi3-hybridpm] SHMEM Interface in Draft External Interfaces
dinan at mcs.anl.gov
Thu Feb 17 17:14:23 CST 2011
Right, there is a mismatch between MPI handles and shared memory
handles. IPC shared memory relies on having a portable handle
(filename, etc) in order to support asynchronous attach/detach to/from
shared allocations. In order to fully support this, we would also need
to have a portable handle. There was an earlier suggestion of letting
the programmer supply a handle. We didn't seem to like it, but that
would get around the problem of needing to share and MPI handle.
Another alternative would be to make attaching to a shmem region
collective. This is tricky too since it would be collective across a
new communicator that includes the added processes. We would also need
a collective detach.
On 2/17/11 2:27 PM, Jeff Squyres wrote:
> In fact, chapter 2 explicitly says that handles only have meaning in the local process.
> On Feb 17, 2011, at 3:19 PM, Hubert Ritzdorf wrote:
>>>> MPI_Comm_shm_attach() is a little tricky - in the current proposal I
>>>> don't think we've defined the shm handle to be portable. Can we make it
>>>> valid to send this to another node-local process in order for them to
>>>> call attach?
>>> Is there an example in MPI where we allow sending an MPI handle to
>>> object between ranks? This seems like a bad idea to me.
>> No, there isn't.
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