[Mpi3-rma] RMA op compatibility matrix

Pavan Balaji balaji at mcs.anl.gov
Fri Oct 14 16:58:39 CDT 2011


I don't think believe that's correct. Both the "local update" and the 
"put or accumulate" parts apply to the overlapping window.

Here's the rule (which can be broken up into two rules):

  * A put or accumulate must not access a target window once a local 
update or a put or accumulate update to another (overlapping) target 
window have started on a location in the target window, until the update 
becomes visible in the public copy of the window.

  * Conversely, a local update in process memory to a location in a 
window must not start once a put or accumulate update to that target 
window has started, until the put or accumulate update becomes visible 
in process memory. In both cases, the restriction applies to operations 
even if they access disjoint locations in the window.

The second half is not relevant here because it's talking about the same 
location, not the same window.

The first half is not relevant here because it's talking about 
overlapping windows.

Even logically, the first rule only makes sense for overlapping windows. 
It doesn't make sense for non-overlapping windows. Why would load + 
Put/Acc be a problem?

  -- Pavan

On 10/14/2011 04:48 PM, James Dinan wrote:
> I think this rule is overloaded to define semantics for both load/store
> and multiple windows.  I believe that the parsing below with bracketed
> text removed is the correct interpretation for this case:
>
> A put or accumulate must not access a target window once a local update
> [or a put or accumulate update to another (overlapping) target window]
> have started on a location in the target window, until the update
> becomes visible in the public copy of the window. Conversely, a local
> update in process memory to a location in a window must not start once a
> put or accumulate update to that target window has started, until the
> put or accumulate update becomes visible in process memory.  In both
> cases, the restriction applies to operations even if they access
> disjoint locations in the window.
>
>    ~Jim.
>
> On 10/14/11 4:36 PM, Pavan Balaji wrote:
>>
>> That rule is for overlapping windows.
>>
>> Pavan Balaji @ iPhone
>> (Big fingers. Small email.)
>>
>> On Oct 14, 2011, at 4:33 PM, James Dinan<dinan at mcs.anl.gov>   wrote:
>>
>>> Rule #3 on page 365 of semantics and correctness:
>>>
>>> --snip--
>>>
>>> 3. A put or accumulate must not access a target window once a local update or a put or accumulate update to another (overlapping) target window have started on a location in the target window, until the update becomes visible in the public copy of the window. Conversely, a local update in process memory to a location in a window must not start once a put or accumulate update to that target window has started, until the put or accumulate update becomes visible in process memory.  In both cases, the restriction applies to operations even if they access disjoint locations in the window.
>>>
>>> A program is erroneous if it violates these rules.
>>>
>>> --snip--
>>>
>>> ~Jim.
>>>
>>> PS- This rule is like five rules.  We really should regroup once the ticket is accepted and see if it can be split into a few smaller, easier to digest rules.
>>>
>>> On 10/14/11 3:18 PM, Pavan Balaji wrote:
>>>>
>>>> Why are they incompatible in MPI-2?
>>>>
>>>> Pavan Balaji @ iPhone
>>>> (Big fingers. Small email.)
>>>>
>>>> On Oct 14, 2011, at 11:18 AM, James Dinan<dinan at mcs.anl.gov>    wrote:
>>>>
>>>>> In MPI-2, the are not compatible, but in MPI-3, it's ok as long as there is no overlap.  I've attached an updated PDF with both MPI-2 and MPI-3 tables.
>>>>>
>>>>> ~Jim.
>>>>>
>>>>> On 10/14/11 2:02 AM, Pavan Balaji wrote:
>>>>>>
>>>>>> There seem to be a few errors here: load + Put/Acc and store + Get
>>>>>> should be NOVL.
>>>>>>
>>>>>> -- Pavan
>>>>>>
>>>>>> On 10/10/2011 02:35 PM, James Dinan wrote:
>>>>>>> Hi All,
>>>>>>>
>>>>>>> We discussed creating a table that shows compatibility between
>>>>>>> concurrent RMA operations. A rough mockup of this table is attached.
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Jim.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> mpi3-rma mailing list
>>>>>>> mpi3-rma at lists.mpi-forum.org
>>>>>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
>>>>>>
>>>>> <rma_op_matrix.pdf>
>>>>> <rma_op_matrix.pptx>

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



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