On Tuesday 19 May 2009, Roman Martonak wrote:
> On Tue, May 19, 2009 at 3:29 PM, Peter Kjellstrom <c...@nsc.liu.se> wrote:
> > On Tuesday 19 May 2009, Roman Martonak wrote:
> > ...
> >> openmpi-1.3.2                           time per one MD step is 3.66 s
> >>    ELAPSED TIME :    0 HOURS  1 MINUTES 25.90 SECONDS
> >>  = ALL TO ALL COMM           102033. BYTES               4221.  =
> >>  = ALL TO ALL COMM             7.802  MB/S          55.200 SEC  =
...
> With TASKGROUP=2 the summary looks as follows
...
>  = ALL TO ALL COMM           231821. BYTES               4221.  =
>  = ALL TO ALL COMM            82.716  MB/S          11.830 SEC  =

Wow, according to this it takes 1/5th the time to do the same number (4221) of 
alltoalls if the size is (roughly) doubled... (ten times better performance 
with the larger transfer size)

Something is not quite right, could you possibly try to run just the alltoalls 
like I suggested in my previous e-mail?

/Peter

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