Hi Tom,

Thank you.  

I haven't still changed my code to run when threading is  needed (presently working). 
I have doubt that when i calculate the MPI ranks using the MPI command  it gives only the nodes which have given in a host file.
But how can i calculate the MPI ranks as you have told i.e N=H(    number of CPUs showing on a node ) x M ( number of nodes in a cluster).

And I would like test like this if have 2 nodes and where I can use up to 50 cores. I would like to scale like 2,4,8,16,32,45 cores and at the same time if use 8 cores then I would like to take the readings as node1- 3cores and node2-5 cores. So in order to do that should I need mention anything in the host file as I have mentioned the No.of nodes.

And can provide me any tutorials which explains with an example programs.


Thanking you,
   

On Mon, Aug 13, 2012 at 6:59 PM, Elken, Tom <tom.elken@intel.com> wrote:

Hi Seshendra,

 

If you have implemented hyperthreading by Enabling it in the BIOS, then when you look at

cat /proc/cpuinfo output, you will see 2x the # of CPUs than the number of cores on your system.

 If that number of CPUs showing on a node = H, and the number of nodes in your cluster with this same configuration is M,   

Then you can run your program on up to N = H x M  MPI ranks,

and your Open MPI  mpirun command can use the

‘-np N –npernode H’   options to indicate this.

 

Note that with some applications, you may see very little benefit to hyperthreading.  In any case, you should also run on “-np N/2” ranks and add the “-npernode H/2” setting to not use more ranks per node than you have cores per node, and compare performance with N ranks (with H per node).

 

-Tom

 

 

From: users-bounces@open-mpi.org [mailto:users-bounces@open-mpi.org] On Behalf Of seshendra seshu
Sent: Monday, August 13, 2012 9:27 AM
To: Open MPI Users
Subject: [OMPI users] Regarding hyperthreding

 

Hi,

I have written an code mpi and an iam trying to implement hyperthreading  environment. So could any one tell me how to implement and run the program in open mpi.

 

Kindly help me.

 

Thanking you,

 

 


--
 WITH REGARDS
M.L.N.Seshendra


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 WITH REGARDS
M.L.N.Seshendra