[mpich-discuss] unbalanced task distribution on SMP nodes

[Pavan Balaji]

We recommend all users to just move to the Hydra process manager. You 
can just do:

% mpiexec.hydra -f mpd.hosts -n 16 my_prog.exe

With Hydra, there's no need to do mpdboot or mpdallexit. You can find 
more information on Hydra here: 
http://wiki.mcs.anl.gov/mpich2/index.php/Using_the_Hydra_Process_Manager

If you want to continue using MPD, you are missing one option in mpdboot:

% mpdboot -n 2 -f mpd.hosts --ncpus=8

The --ncpus option tells mpdboot how many processes to launch on the 
local node.

  -- Pavan

On 05/13/2010 09:06 AM, Ping Luo wrote:
> Hi,
> 
> I am recently testing an MPI code with mpich2. The code and mpich2 
> were compiled with gcc. I tried to run the code on two nodes, each
> with 8 cores, hoping that each node will have 8 tasks. However, one
> node ended up with 11 tasks and the other 5, very unbalanced. The 
> commands that I launched the code are as follow:
> 
> $ mpdboot -n 2 -v -f mpd.hosts
> $ mpiexec -n 16 my_prog.exe
> $ mpdallexit
> 
> 
> $ more mpd.hosts 
> node001:8
> node002:8
> 
> 
> 
> What has gone wrong and how to make 8 tasks per node?
> 
> 
> Please help,
> 
> 
> 

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