On Mon, 17 Jan 2011, Matthew Knepley wrote: > > (3) Should I run the mpd daemon before using mpiexec??? On the MPICH2 that > > I had installed prior to my PETSc it required me type "mpd &" > > before program execution. > > > > But it seems for my PETSc mpiexec I don;t need mpd. But should I type it in > > ?? I mean I am not sure if this affects program performance > > > > The new version of MPICH uses hydra, not mpd, to manage the startup.
Actually with petsc-3.1 download-mpich uses pm=gforker [not hydra], which limits MPI to a single node [with fork for all the mpi jobs] If you need something more specific with MPI config you should build your own MPI appropriately - and then configure PETSc with it - or specify additional configure options to --download-mpich ./configure --help |grep mpich With petsc-dev we default to '--with-pm=hydra --with-hydra-bss=fork,ssh' so again mpiexec will again default to fork [i.e 1 node] But one can use ' mpiexec -bootstrap ssh' to switch to multi-node hydra. PETSc defaults cater to easy software deveopment [this default works for most users]. Performance runs with mult-nodes are usually done on clusters/high performance machines - which usually have a tuned MPI installed on it anyway.. Satish
