https://github.com/open-mpi/ompi/pull/285 is a potential answer. I would like to hear Dave Goodell comment on this before pushing it upstream.
George. On Wed, Nov 19, 2014 at 12:56 PM, George Bosilca <bosi...@icl.utk.edu> wrote: > Dave, > > You’re right, we screwed up (some #define not correctly set). I have a > patch, I’ll push it asap. > > George. > > > On Nov 19, 2014, at 05:19 , Dave Love <d.l...@liverpool.ac.uk> wrote: > > > > "Daniels, Marcus G" <mdani...@lanl.gov> writes: > > > >> On Mon, 2014-11-17 at 17:31 +0000, Dave Love wrote: > >>> I discovered from looking at the mpiP profiler that OMPI always uses > >>> gettimeofday rather than clock_gettime to implement mpi_wtime on > >>> GNU/Linux, and that looks sub-optimal. > >> > >> It can be very expensive in practice, especially for codes that have > >> fine-grained instrumentation. > > > > OK, but I assumed VT would take that sort of thing into account for > > platforms I don't have. clock_gettime(CLOCK_MONOTONIC,) is as fast as > > gettimeofday on our mainstream sort of system (RHEL6, sandybridge); > > CLOCK_MONOTONIC_COARSE is about three times faster. [I can't find that > > sort of information in Linux doc.] > > > > Perhaps there should be a choice via an MCA parameter, but it looks as > > though it should default to clock_gettime on x86_64 Linux. I suppose > > one can argue what "high resolution" means in the mpi_wtime doc, but I'd > > rather not. > > _______________________________________________ > > users mailing list > > us...@open-mpi.org > > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > > Link to this post: > http://www.open-mpi.org/community/lists/users/2014/11/25844.php > >
