[Beowulf] IB DDR: mvapich2 vs mvapich performance

[Mikhail Kuzminsky]

I have up to 1453 MB/s for 4MB message size (1453.5, 1453.7 for a pair 
of subsequent runs) on osu_bw test w/Mellanox DDR IB (Mellanox version 
of OFED-1.2, w/binary mvapich-0.9.9); OpenMPI -1.2.2-1 gives even a 
bit more (1470 MB/s - more exactly, 1469.753328,  1469.447179, 
1469.977840 for 3 subsequent test runs).

The SC'07 message of D.K.Panda
http://mvapich.cse.ohio-state.edu/publications/sc07_mpich2_bof.pdf
inform us about 1405 MB/s.

Is this throughput difference the result of MPI-2 vs MPI 
implementation or should I beleive that this difference (about 4% for 
my mvapich vs mvapich2 at SC'07 ) is not significant  - in the sense 
that it is simple because of some measurement errors (inaccuracies)? 

Mikhail Kuzminsky
Computer Assistance to Chemical Research Center
Zelinsky Institute of Organic Chemistry
Moscow