[Mpi3-hybridpm] Hybrid WG meeting at the Forum

[Ron Brightwell]

On 12/07/2010 08:55 AM, James Dinan wrote:
> If it's implemented using BSD mmap then all nodes will need to give the
> same filename to map.  My feeling is that if MPI can reliably generate
> the key/filename/whatever for us then it's unnecessary complexity to put
> this in the user interface.
>
>    ~Jim.
>
> On 12/7/10 7:58 AM, Douglas Miller wrote:
>> In order to ensure all nodes get the same memory segment, they all have
>> to use the same "key". At least if this is implemented on Unix SysV or
>> POSIX shmem. Then there's the possibility of some nodes allocing on a
>> sub-comm first, etc. I think its just avoiding a lot of potential
>> complications and don't see what the downside is.
>>

I agree with Jim. Communicators are supposed to hide this kind of 
complexity from the user.

We could also limit the number of shared memory regions to one per 
communicator, essentially forcing the user to dup a communicator if it 
wants more than one.

-Ron