[mpich-discuss] Not able to run MPI program parallely...

[Pavan Balaji]

On 05/02/2012 04:35 AM, Albert Spade wrote:
> Here is my sample runs with different number of processes. One thing
> which I observed and not able to figure out is, as I am increasing the
> number of processes the error is decreasing upto 5 processes. But when I
> run it for 16 processes the error has increased, which I think has to be
> decreased. Can you please tell me why this is happening?

The program is not trying to increase accuracy with more processes. 
It's just trying to increase speed.  If you increase the number of 
computations (default is 10000), you'll see a speed difference.  You can 
look through the benchmark in examples/cpi.c.

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