> -----Original Message----- > From: users-boun...@open-mpi.org > [mailto:users-boun...@open-mpi.org] On Behalf Of Reuti > Sent: Tuesday, October 21, 2008 11:36 AM > To: Open MPI Users > Subject: Re: [OMPI users] OpenMPI runtime-specific > environment variable? > > Hi, > > Am 21.10.2008 um 18:52 schrieb Ralph Castain: > > > On Oct 21, 2008, at 10:37 AM, Adams, Brian M wrote: > > > >> Doug is right that we could use an additional command line flag to > >> indicate MPI runs, but at this point, we're trying to hide > that from > >> the user, such that all they have to do is run the binary vs. > >> orterun/mpirun the binary and we detect whether it's a serial or > >> parallel run. > > And when you have this information you decide for your user, > whether to use mpirun (and the correct version to use) or > just the plain binary?
I might have created some confusion here too. The goal is to build an MPI-enabled binary 'foo' which a user may invoke as (1) ./foo -OR- (2) mpirun -np 4 ./foo The binary foo then determines at run-time whether it is to run in (1) serial, where MPI_Init will never be called; or (2) parallel, calling MPI_Init and so on. This is a historical behavior which we need to preserve, at least for our present software release. > You are making something like "strings the_binary" and grep > for indications of the compilation type? For the standard > Open MPI with shared libraries a "ldd the_binary" might > reveal some information. Hadn't thought to do that actually, since it addresses a slightly different problem than I propose above. Thanks for the suggestion. This is another possibility if instead of doing this detection directly in our binary, we decide to change to a wrapper script approach. In any case, I appreciate all the discussion -- I believe I have a reasonable path forward using a combination of pre-processor defines that the OMPI wrappers and headers make with the runtime environment variables Ralph suggested (I'll just check for both the <1.3 and >= 1.3 environment cases). Brian
