Terry, Is there any way you can quantify the cost ? This seems reasonable, but would be nice to get an idea what the performance cost is (and not within a tight loop where everything stays in cache).
Rich On 12/16/08 10:41 AM, "Terry D. Dontje" <terry.don...@sun.com> wrote: > WHAT: To make predefined handles extern to pointers instead of an > address of an extern to a structure. > > WHY: To make OMPI more backwards compatible in regards to changes to > structures that define predefined handles. > > WHERE: In the trunk. ompi/include/mpi.h.in and places in ompi that > directly use the predefined handles. > > WHEN: 01/24/2009 > > TIMEOUT: 01/10/2009 > > > ____________________ > > The point of this change is to improve the odds that an MPI application > does not have to recompile when changes are made to the OMPI library. > In this case specifically the predefined handles that use the structures > for communicators, groups, ops, datatypes, error handlers, win, file, > and info. > > An example of the changes for the communicator predefined handles can be > found in the hg tmp workspace at > ssh://www.open-mpi.org/~tdd/hg/predefcompat. > > Note, the one downfall that Jeff and I could think of by doing this is > you potentially add one level of indirection but I believe that will be > a small overhead and if you use one of the predefined handles > repetitively (like in a loop) that the address will probably be stored > in a register once and no additional over should be seen due to this change. > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel
