[mpich-devel] tackling "large datatype" change

[Pavan Balaji]

Rob,

Sorry, I'll look into this next week.

Amount of time left is proportional to age of baby.

The first solution works for some cases in MPICH, but there are still 
many bugs.  I think your ticket is to fix this part?

The second solution is known not to work.

  -- Pavan

On 07/12/2013 06:25 AM, Rob Latham wrote:
> I've been trying to tackle tt #1742, #1890, and #1893 as part of some
> I/O work that uses large datatypes.
>
> Am I stepping on anyone's toes here?  Pavan, I know i bugged you about these
> tickets.  Hope I didn't waste my Thursday on this...
>
> Pavan told me there are two problems here, but I think there are
> really one solution to both:
>
> - large datatype means a datatype that describes more than 2 gigs of
>    data.  A million contigs of a million contigs, say
>
> - large count means datatypes that use MPI_Count to say how many
>    elements they have:  a contig of 3 billion MPI_BYTES, say
>
> Internally, though, there's no way to decouple those two problems.
>
> The changes are pervasive and make me really nervous.
>
> I've been sometimes pushing changes to the ticket-1742-bigio branch.
>
> Who can review datatype changes once I'm done?:
>
> ==rob
>

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