[gmx-users] Scaling on IBM/SP2 Power3

[Anton Feenstra]

Hi All,


I'm examining the scaling properties on our IBM/SP2 Power3 AIX4.3
16/32 cpus/node machine here. Problem is, at 10 cpu's (all on one
node) scaling is down to 50-55% (for a 40000 atoms system). Looking
at the scaling benchmarks on the Gromacs page, I'd expect something
well above 70-80% at least! Worse, for the 2 cpu job scaling is
already only 94% while that should be close(r) to 100%. 

I am now trying to convince the loadleveler to run a new job with
MP_EAGER_LIMIT=65536, which should reduce message sending latency
for MPI. I've already set '#@network.mpi = csss,shared,us' and
MP_SHARED_MEMORY=yes, which should convince MPI to use shared
memory communication. 

I'd appreciate any comments and/or other suggestions!


-- 
Groetjes,

Anton
 ________ ___________________________________________________________
|        | Anton Feenstra                                            |
| .      | Dept. of Pharmacochemistry - Vrije Universiteit Amsterdam |
| |----  | De Boelelaan 1083 - 1081 HV Amsterdam - The Netherlands   |
| |----  | Tel: +31 20 44 47608 - Fax: +31 20 44 47610               |
| ' __   | Feenstra at chem.vu.nl - http://www.chem.vu.nl/afdelingen/FAR|
|  /  \  |-----------------------------------------------------------|
| (    ) | Dept. of Biophysical Chemistry - University of Groningen  |
|  \__/  | Nijenborgh 4 - 9747 AG Groningen - The Netherlands        |
|   __   | Tel +31 50 363 4327 - Fax +31 50 363 4800                 |
|  /  \  | K.A.Feenstra at chem.rug.nl - http://md.chem.rug.nl/~anton   |
| (    ) |-----------------------------------------------------------|
|  \__/  | "It's Bicycle Repair Man !" (Monty Python)                |
|________|___________________________________________________________|