[gmx-developers] alternate parallelization in src/gmxlib/network.c ?

Nathan Moore nmoore at physics.umn.edu
Tue Jun 14 03:55:30 CEST 2005

I'm presently working to port Gromacs to the IBM Blue Gene architecture. 
The parallel benchmark on the GROMACS website (dpcc) scales only to about
30-40 processors, and seems to slow down at sizes larger than 128 nodes. 
I'm hoping to extend scalability to at least 512 processors and thought a
first step might be to try a different message passing scheme (tuned
versions of All to All are available for the architecture and the message
passing intereconnect is quite fast).  From reading the manual this change
seems easy to implement in the communicate_r function but much to my
embarrassment I seem to be completely incapable of finding the function
definition in the source.  Would anyone care to share where this function
is defined?  grep "communicate_r" * */* */*/* doesn't return anything from
the top of the source tree...  I assume there's a similar "communicate_f"
that would need to be revised as well.

Also, if this sort of message passing routine has been implemented in
previous source revisions, I'd love to read about it.

best regards,

Nathan Moore
Minneapolis MN

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