Not quite. I said that it works for some cases, but there are bugs. -- Pavan On 07/12/2013 10:32 AM, Jeff Hammond wrote:
Pavan indicated to me in another conversation that the internal overflow issues were fixed. You can fight with him about the correctness of that statement :-)
Jeff
----- Original Message -----
From: "David Goodell (dgoodell)" <[email protected]> To: "<[email protected]>" <[email protected]> Sent: Friday, July 12, 2013 10:13:37 AM Subject: Re: [mpich-devel] tackling "large datatype" change
Jeff,
How could this possibly work correctly with broken (i.e., uses "int"s internally for certain calculations) datatype and communication engines?
The hard part of large count types is not constructing the actual type, it's processing that type correctly throughout the entire stack...
-Dave
On Jul 12, 2013, at 9:57 AM, Jeff Hammond <[email protected]> wrote:
Hi Rob,
I started working on something to address this a few weeks ago. I was going to write a portable (i.e. above MPI) implementation of
MPIX_Type_contiguous_x(MPI_Count count, MPI_Datatype old_type, MPI_Datatype *newtype)
and then reimplement it efficiently in MPICH. I will also try to get JeffS or DaveG to create it for OtherMPI so e.g. PETSc can use it more broadly.
Does this sound like an okay plan to you? I've not pushed the latest code to Github but when I do, I'll send you the link.
Best,
Jeff
----- Original Message -----
From: "Rob Latham" <[email protected]> To: [email protected] Sent: Friday, July 12, 2013 6:25:14 AM Subject: [mpich-devel] tackling "large datatype" change
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
-- Rob Latham Mathematics and Computer Science Division Argonne National Lab, IL USA
-- Jeff Hammond Argonne Leadership Computing Facility University of Chicago Computation Institute [email protected] / (630) 252-5381 http://www.linkedin.com/in/jeffhammond https://wiki.alcf.anl.gov/parts/index.php/User:Jhammond ALCF docs: http://www.alcf.anl.gov/user-guides
-- Pavan Balaji http://www.mcs.anl.gov/~balaji