[Mpi3-hybridpm] Hybrid WG meeting at the Forum

[Douglas Miller]

It's just that providing a "more meaningful" key can help when debugging or
managing through the OS. You still have to generate some sort of "sequence"
number per-communicator, as successive allocations on the same communicator
must return different memory. So, communicator alone is not enough to
uniquely identify/select an allocation. Implementations will have to
generate a "key" to pass to the OS, and so all ranks must be able to
generate identical keys for corresponding calls.


_______________________________________________
Douglas Miller                  BlueGene Messaging Development
IBM Corp., Rochester, MN USA                     Bldg 030-2 A410
dougmill at us.ibm.com               Douglas Miller/Rochester/IBM


                                                                           
             Pavan Balaji                                                  
             <balaji at mcs.anl.g                                             
             ov>                                                        To 
                                       mpi3-hybridpm at lists.mpi-forum.org   
             12/07/2010 08:08                                           cc 
             AM                        Douglas Miller/Rochester/IBM at IBMUS  
                                                                   Subject 
                                       Re: [Mpi3-hybridpm] Hybrid WG       
                                       meeting at the Forum                
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





On 12/07/2010 07:58 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.

In that sense, isn't the communicator a "key"?

  -- Pavan

--
Pavan Balaji
http://www.mcs.anl.gov/~balaji

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