[Mpi3-rma] MPI RMW operations

[Brian W. Barrett]

That makes sense.  How would an MPI_Rmw() call with the IMPLICIT  
epoch interact with explicit epochs?  If the answer is "it wouldn't",  
I think that's valid.  We just need to state it.

Also, is there any reason we're not using the standard OP defines?

Brian

On Mar 25, 2008, at 9:14 AM, Howard Pritchard wrote:

> Hello Brian,
>
> That was the idea.
>
> The problem as we saw it is that in non-mpi shared memory
> applications, atomic memory operations are typically used for  
> lightweight
> synchronization.  Having to always use potentially heavyweight lock/ 
> unlock
> sequences seems to defeat the purpose of adding rmw operations to the
> mpi specification.
>
> This is a special case of the more general discussion that we should
> have about global visibility of rma operations, etc.
>
> Howard
>
> Brian W. Barrett wrote:
>
>> If MPI_MODE_PASSIVE_EPOCH_IMPLICIT is not given, is synchronization
>> explicit using the standard epoch functions?
>>
>> Brian
>>
>> On Mar 24, 2008, at 9:09 PM, Shipman, Galen M. wrote:
>>
>>
>>
>>> Howard and I have been working on the RMW operations listed below  
>>> for
>>> consideration.
>>>
>>> - Galen Shipman - ORNL
>>>
>>>
>>> Single operand RMW operations
>>>
>>> MPI_Rmw(void *operand_addr,
>>>                     int count,
>>>                    MPI_Datatype datatype,
>>>                    void *result_addr,
>>>                    int target_rank,
>>>                    MPI_Aint target_disp,
>>>                    int assert,
>>>                    MPI_RMW_Op op,
>>>                     MPI_Win win)
>>>
>>>
>>> Two operand RMW operations
>>>
>>> MPI_Rmw2(void *operand_addr,
>>>                       int count,
>>>                       MPI_Datatype datatype,
>>>                      void *operand2_addr,
>>>                      void *result_addr,
>>>                      int target_rank,
>>>                      MPI_Aint target_disp,
>>>                       int assert,
>>>                      MPI_RMW_2_Op op,
>>>                       MPI_Win win)
>>>
>>>
>>>
>>> MPI_RMW_Op Predefined RMW single operand operations
>>> The following predefined operations are supplied for MPI_RMW and
>>> related
>>> functions. These operations are invoked  by placing the following
>>> in op.
>>>
>>> Name             Meaning
>>>
>>> MPI_RMW_INC             increment
>>> MPI_RMW_PROD    product
>>> MPI_RMW_SUM             sum
>>> MPI_RMW_LAND    logical and
>>> MPI_RMW_LOR             logical or
>>> MPI_RMW_LXOR    logical xor
>>> MPI_RMW_BAND    binary and
>>> MPI_RMW_BOR             binary or
>>> MPI_RMW_BXOR    binary xor
>>> MPI_RMW_SWAP    swap value
>>>
>>> MPI_RMW_2_Op Predefined RMW two operand operations
>>>
>>> Name                                            Meaning
>>>
>>> MPI_RMW2_MASK_SWAP      swap masked bits
>>> MPI_RMW2_COMP_SWAP      compare and swap
>>>
>>> Note: MPI_RMW2_COMP_SWAP is an equality comparison, we may wish to
>>> consider multiple comparison operations such as >, >=, <, <=, ==,  
>>> <>.
>>>
>>> Both MPI_Rmw and MPI_Rmw2 take an assert argument.
>>> When assert == MPI_MODE_PASSIVE_EPOCH_IMPLICIT MPI_Rmw/2 is
>>> equivalent to:
>>>
>>> MPI_Win_lock(target_rank,0,win);
>>> MPI_Rmw(.....);
>>> MPI_Win_unlock(target_rank,0,win);
>>>
>>> When assert  == MPI_MODE_PASSIVE_EPOCH_IMPLICIT | MPI_MODE_NOCHECK
>>> the MPI library knows that the window lock at the target need not be
>>> acquired.
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> mpi3-rma mailing list
>>> mpi3-rma at lists.mpi-forum.org
>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
>>>
>>>
>>>
>>
>>
>>
>
>
> --
>
> Howard Pritchard
> Cray Inc.
>
>
> _______________________________________________
> mpi3-rma mailing list
> mpi3-rma at lists.mpi-forum.org
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
>

-- 
   Brian W. Barrett
   Dept. 1422: Scalable Computer Architectures
   Sandia National Laboratories