[mpich-discuss] Restrict number of cores, not threads

Dear all, I am working on a shared memory processor with 256 cores. I am working from the command line directly. Can I restict the number of cores that I deploy.The command mpirun -n 100 myprog will automatically start on 100 cores. I wish to use only 10 cores and have 10 threads on each core. Can I do this with mpich ? Rememebre that this an smp abd I can not identify each core individually(as in a cluster) Regards, bob