[mpiwg-rma] Proposed Info Key

[Jeff Hammond]

I contend that https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/397
is the right way to solve this problem.  Using overlapping windows
here is unscalable because if you have one win_create for every
process in the node on top of one win_allocate_shared per node, you
end up with ppn+1 windows to hack the effect of one win_allocate if my
ticket is passed.  This is pretty significant overhead if one wants to
run OpenSHMEM on an Intel Xeon Phi...

And note that the time to setup all these windows properly is
nontrivial.  It has been measured in the context of another project.
I can't share the details since it's not published and I'm not in a
position to decide to share it at this point.

Jeff

On Tue, Oct 14, 2014 at 7:42 AM, Jim Dinan <james.dinan at gmail.com> wrote:
> This is an info key that e.g. OSHMPI could use to tell MPI that the buffer
> being passed to MPI_Win_create was allocated via MPI_Win_allocate_shared.
> If this is already covered by another ticket, let me know the existing trac
> number and I will close this one.  If we want to pursue this as a 3.0
> erratum, we could utilize this new ticket.
>
>  ~Jim.
>
> On Tue, Oct 14, 2014 at 10:38 AM, Jeff Hammond <jeff.science at gmail.com>
> wrote:
>>
>> I don't fully understand. Is this designed to make it easier to use the
>> overlapping windows trick because we can get at shm inside of other window
>> types? I have a ticket that solves that issue holistically already...
>>
>> Sent from my iPhone
>>
>> On Oct 14, 2014, at 7:17 AM, Jim Dinan <james.dinan at gmail.com> wrote:
>>
>> Hi All,
>>
>> Please see the ticket:
>> https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/460
>>
>> For a new info key that was proposed by Mikhail Brinsky of Intel.
>>
>> Thanks,
>>  ~Jim.
>>
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-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/