[MPICH] Problem with MPI_Gather

[Pavan Balaji]

Sending the correction patch to mpich-discuss as well.

 -- Pavan

Jonathan Patterson wrote:
>> Hello, Jonathan!
>> I have tested your example with mpich2 1.0.6 the previous stable release of 
> mpich2 and
>> found the example work correctly. I have compiled your program with 
> mpich2-1.0.6p1 with
>> gather.c taken from src/mpi/coll of mpich2-1.0.6 distribution and found the 
> example to work
>> as well. The problem with 1.0.6p1 seems to show only with messages of size 
> greater than the
>> value of MPIR_GATHER_VSMALL_MSG set in mpiimpl.h . Currently this constant is 
> set to
>> 1024 bytes which explains why reducing DATASIZE to less than 256 removes the 
> bug on
>> 32 bit machines. I hope someone from the developers will come up with a fix 
> soon, since
>> the algorithm seems to have been slightly modified in 1.0.6p1.
> 
> 	Thanks a lot for your very helpful reply. I'll submit it as a bug.
> 

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