On 12/26/2011 12:12 PM, Torsten Hoefler wrote:
> On Mon, Dec 26, 2011 at 12:22:38AM -0600, Pavan Balaji wrote:
>>
>> On 12/09/2011 03:36 PM, Torsten Hoefler wrote:
>>>> 3) allocate_shared proposal with MPI_Win_lock_all(exclusive)
>>> - remove MPI_Win_lock_all(exclusive) from the proposal and re-read
>>
>> Why was this removed?
> Brian and others felt that an implementation on a distributed-memory
> network would put a huge burden on the implementers and may cause other
> problems. A workaround offering essentially the same functionality by
> using point-to-point and collective synchronization (i.e., block p-1
> processes in a barrier while one process updates the shared memory) was
> identified.

Didn't we already discuss this in one of the working groups (though I 
forget whether it was RMA or hybrid)?  If I recall correctly, a non-RMA 
solution was shot down because it doesn't provide the memory barriers 
that a lock/unlock would do.

Someone also pointed out that we could do a for loop of 
Win_lock(exclusive) to achieve the same result, but it was not scalable.

  -- Pavan

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