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