Hi Andrew, In your distribution of ompi, do you include versions of ompi to support different MPI thread safetylevels? In particular, do you include a library which supports MPI_THREAD_MULTIPLE? Just trying to better understand the requirements of you ompi package in terms of MPI thread safety.
Thanks, Howard 2014-10-30 8:10 GMT-06:00 Friedley, Andrew <andrew.fried...@intel.com>: > Hi, > > I'm reporting a performance (message rate 16%, latency 3%) regression when > using PSM that occurred between OMPI v1.6.5 and v1.8.1. I would guess it > affects other networks too, but I haven't tested. The problem stems from > the --enable-smp-locks and --enable-opal-multi-threads options. > > --enable-smp-locks defaults to enabled and, on x86, causes a 'lock' prefix > to be prepended to ASM instructions used by atomic primitives. Disabling > removes the 'lock' prefix. > > In OMPI 1.6.5, --enable-opal-multi-threads defaulted to disabled. When > enabled, OPAL would be compiled with multithreading support, which included > compiling in calls to atomic primitives. Those atomic primitives, in turn, > potentially use a lock prefix (controlled by --enable-smp-locks). > > SVN r29891 on the trunk changed the above. --enable-opal-multi-threads > was removed. CPP macros (#if OPAL_ENABLE_MULTI_THREADS) controlling > various calls to atomic primitives were removed, effectively changing the > default behavior to multithreading ON for OPAL. This change was then > carried to the v1.7 branch in r29944, Fixes #3983. > > We can use --disable-smp-locks to make the performance regression go away > for the builds we ship, but we'd very much prefer if performance was good > 'out of the box' for people that grab an OMPI tarball and use it with PSM. > > My question is, what's the best way to do that? It seems obvious to just > make --disable-smp-locks the default, but I presume the change was done on > purpose, so I'm looking for community feedback. > > Thanks, > > Andrew > _______________________________________________ > devel mailing list > de...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/devel > Link to this post: > http://www.open-mpi.org/community/lists/devel/2014/10/16130.php >
