[Mpi3-rma] [EXTERNAL] Re: Disp_unit in allocate_shared should be returned by win_shared_query?

[Bronis R. de Supinski]

Torsten:

It is too large of a change for a chapter committee just to add.
In the least, you need to poll the full forum list.

Bronis



On Sun, 22 Jul 2012, Torsten Hoefler wrote:

> Dear All,
>
> I think we should discuss this more. Right now, we still have more votes
> in favor of this than against. The change is still committed and part of
> the "official release". The deadline is 7/26.
>
> Please advise what to do!
>
> Thanks,
>  Torsten
>
> On Wed, Jul 18, 2012 at 08:11:23PM +0000, Barrett, Brian W wrote:
>> I'm concerned with the change (and don't think it should happen at this point, as I want to be able to tell other people their changes are too big).  It's probably not another O(p) structure, since a process will have to know the other rank's disp_unit to do the memcpy during the communication operations, so we crossed the O(p) bridge when we added disp_unit to allocate_shared.
>>
>>
>> Brian
>>
>> --
>>   Brian W. Barrett
>>   Scalable System Software Group
>>   Sandia National Laboratories
>> ________________________________________
>> From: mpi3-rma-bounces at lists.mpi-forum.org [mpi3-rma-bounces at lists.mpi-forum.org] on behalf of Jim Dinan [dinan at mcs.anl.gov]
>> Sent: Wednesday, July 18, 2012 12:46 PM
>> To: mpi3-rma at lists.mpi-forum.org
>> Subject: [EXTERNAL] Re: [Mpi3-rma] Disp_unit in allocate_shared should be returned by win_shared_query?
>>
>> It's not inherently damaging, but it requires us to maintain/provide
>> access to another O(p) structure and suggests to users that another
>> process' disp_unit is useful information, which is incorrect.  IIRC, we
>> did discuss this in the working group and intentionally omitted it.
>>
>>   ~Jim.
>>
>> On 7/18/12 1:38 PM, Torsten Hoefler wrote:
>>> On Wed, Jul 18, 2012 at 01:18:53PM -0500, James Dinan wrote:
>>>> On 7/18/12 1:06 PM, Torsten Hoefler wrote:
>>>>> On Wed, Jul 18, 2012 at 01:08:43PM -0500, Pavan Balaji wrote:
>>>>>>
>>>>>> On 07/18/2012 01:02 PM, Torsten Hoefler wrote:
>>>>>>> Jim,
>>>>>>>> Is one process' disp_unit meaningful at another process?  I thought that
>>>>>>>> this is not the case.  MPI provides no other routines to query another
>>>>>>>> process' disp_unit.
>>>>>>> It is something that the user is passing in. I don't know of a
>>>>>>> particular use-case but we can query all other arguments that each
>>>>>>> process passed. One more integer seemed safe to me.
>>>>>>>
>>>>>>>> Also, what meaning does a disp_unit have in the context of load/store
>>>>>>>> operations that will result from win_shared_query?
>>>>>>> Nothing.
>>>>>>>
>>>>>>>> Maybe I'm missing something, but this doesn't seem necessary.
>>>>>>> Well, it's better to have it than to introduce it with a different name
>>>>>>> later. That was my main motivation. One could also use it in a library
>>>>>>> context to query. But that's weak, I know.
>>>>>>
>>>>>> This doesn't seem critical, and can always be added in MPI-3.1 if we
>>>>>> find it necessary.  No reason to rush it.
>>>>>
>>>>> It cannot be added without a new function name. That was the concern
>>>>> here. Adding it seems less risk than not adding it. In addition, it is
>>>>> already added ;-).
>>>>
>>>> I am concerned that this is a harmful change.  The disp_unit from one
>>>> process has no meaningful use at another process.  If the user wants to
>>>> know it for some reason, they can use a separate communication operation.
>>> I believe the potential damage is very limited. But we can have a vote.
>>>
>>> So far it's still yes: 5, no: 1
>>>
>>> I'm just mediating, not making decisions.
>>>
>>> Torsten
>>>
>>
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>
> -- 
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> Torsten Hoefler         | Performance Modeling and Simulation Lead
> Blue Waters Directorate | University of Illinois (UIUC)
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