[Mpi3-bwcompat] MPI_Count mixing with int...

[Quincey Koziol]

On Jul 8, 2010, at 11:26 AM, Fab Tillier wrote:

> Quincey Koziol wrote on Thu, 8 Jul 2010 at 06:44:37
> 
>> 
>> On Jul 7, 2010, at 8:16 AM, Rajeev Thakur wrote:
>> 
>>> Can we define both (to be the same) since we are familiar with count
>>> for messages (it is a count of datatypes) and size for others.
>> 
>> 	I agree - we shouldn't conflate counts and sizes, they are
>> totally different things.  Defining them both makes sense to me.
> 
> But they are the same for the MPI_PACKED datatype, so really shouldn't be different.

        I'm not looking at the standard document right now, but that just strikes me as the standard being vague about the difference between the two.

> As an aside, can count ever be larger than size_t?

        I would imagine so - on a 32-bit CPU/system with a 64-bit file system.

                Quincey

> -Fab
> 
>>>> -----Original Message----- From: mpi3-bwcompat-bounces_at_[hidden]
>>>> [mailto:mpi3-bwcompat-bounces_at_[hidden]] On Behalf Of Jeff Squyres
>>>> Sent: Wednesday, July 07, 2010 7:24 AM To: MPI-3 backwards
>>>> compatability WG Subject: Re: [Mpi3-bwcompat] MPI_Count mixing with
>>>> int...
>>>> 
>>>> On Jul 7, 2010, at 2:23 AM, Fab Tillier wrote:
>>>> 
>>>>> Would anyone object if we defined MPI_Size rather than
>>>> MPI_Count, and used it for count, position, and size
>>>> parameters?  We could then tackle the issues with
>>>> MPI_Pack/Unpack/Pack_size/Type_size at the same time as
>>>> counts.  We can't use MPI_Aint here since we want to be able
>>>> to be backward compatible, so must provide a separate type
>>>> that can be defined as a standard integer.
>>>> 
>>>> I agree that tackling them all at the same time is the Right
>>>> Thing to do.  I also agree with all your other points.
>>>> 
>>>> I still am a little uncomfortable with the name "MPI_Size"
>>>> because sizes and counts are theoretically different things.
>>>> But then again, I can't think of a better name offhand...
>>>> 
>>>> --
>>>> Jeff Squyres
>>>> jsquyres_at_[hidden]
>>>> For corporate legal information go to:
>>>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>>> 
>>>> 
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