Probably the part of the calculation done on the GPU is not rate limiting. There's no point having four chefs to make one dish...
Look at the beginning and end of your .log files for diagnostic information. If this is a single node, you should be using threadMPI, not real MPI. Generally four CPU cores vs four GPU cores will require an extremely large PP load for the GPUs to all be effective. Mark On Fri, Apr 26, 2013 at 8:35 PM, Albert <mailmd2...@gmail.com> wrote: > Dear: > > I've got two GTX690 in a a workstation and I found that when I run the md > production with following two command: > > mpirun -np 4 md_run_mpi > > or > > mpirun -np 2 md_run_mpi > > the efficiency are the same..... I notice that gromacs can detect 4 GPU > (probably because GTX690 have two core..): > > 4 GPUs detected on host node4: > #0: NVIDIA GeForce GTX 690, compute cap.: 3.0, ECC: no, stat: compatible > #1: NVIDIA GeForce GTX 690, compute cap.: 3.0, ECC: no, stat: compatible > #2: NVIDIA GeForce GTX 690, compute cap.: 3.0, ECC: no, stat: compatible > #3: NVIDIA GeForce GTX 690, compute cap.: 3.0, ECC: no, stat: compatible > > > why the "-np 2" and "-np 4" are the same efficiency? shouldn't it be > faster for "-np 4" ? > > thank you very much > > Albert > > -- > gmx-users mailing list gmx-users@gromacs.org > http://lists.gromacs.org/**mailman/listinfo/gmx-users<http://lists.gromacs.org/mailman/listinfo/gmx-users> > * Please search the archive at http://www.gromacs.org/** > Support/Mailing_Lists/Search<http://www.gromacs.org/Support/Mailing_Lists/Search>before > posting! > * Please don't post (un)subscribe requests to the list. Use the www > interface or send it to gmx-users-requ...@gromacs.org. > * Can't post? Read > http://www.gromacs.org/**Support/Mailing_Lists<http://www.gromacs.org/Support/Mailing_Lists> > -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
