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Long integers in GSMap needed for large grids #31

Open rljacob opened 9 years ago

rljacob commented 9 years ago

(copied from MCT's old bugzilla)

User's with large grids need long int support in GSMap. "I am using MCT to perform communication and remapping operations between two dummy models. For that tests, I'm defining the domain sizes, let say, 32768x32768 and 49152x49152. That produces a sparse matrix for the interpolation with size in the order of 1.07 billion and 2.4 billion of points respectively. However, when I compile MCT in a Cray XE6 machine (Hopper) and I try to run it, I got negative values for the number of points indicating the integer data type is not long enough."

"What I'm doing is very simple. A 2048x1024x1024 3D array is redistributed from M processes of component 1 to N processes of component 2. In this case the total number of grid points is 2048_1024_1024=2147483648, which overflow the 32bit integer. As a result, the init of MCT global map gave the following errors: "mGlobalSegMap::initp: non-positive value of gsize error, stat =-2147483648""

jedwards4b commented 9 years ago

The mct_gsmap_orderedpoints rountine will return an integer array with overflowed values without reporting an error.

rljacob commented 9 years ago

This sounds like a bug. How did you trigger it?

jedwards4b commented 9 years ago

Found it in a call from seq_io_mod - before I go about trying to reproduce it I'm pretty sure that you will see the problem by just looking at the code in OrderedPoints in m_GlobalSegMap.F90

On Fri, Jul 10, 2015 at 1:24 PM, Robert Jacob notifications@github.com wrote:

This sounds like a bug. How did you trigger it?

— Reply to this email directly or view it on GitHub https://github.com/MCSclimate/MCT/issues/31#issuecomment-120501601.

Jim Edwards

CESM Software Engineer National Center for Atmospheric Research Boulder, CO