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).





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



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,