Sounds like the problem comes down to just 32-bit systems that fault on unaligned 8-byte loads. That would be SPARC, IA64 and MIPS. For IB only SPARC is relevant.
So perhaps alignment>2 should be conditional on 32-bit SPARC target. Additionally, an experiment to see if 4-byte alignment is "good enough" (instead of 8) might allow one to save a little space. -Paul On Wed, Feb 20, 2013 at 1:51 PM, Nathan Hjelm <hje...@lanl.gov> wrote: > I talked to Pasha about the change. He suggests fragments are 2-byte > aligned to save space. I suspect that on 64-bit platforms the fragment size > is already a multiple of 8 bytes so this change will likely only affect > 32-bit systems (which is where the bus error is occurring). > > -Nathan > > On Wed, Feb 20, 2013 at 09:39:09PM +0000, Joshua Ladd wrote: > > I would hold off, if possible, until I can investigate the issue. I > don't, off-hand, know why the 2-byte alignment, although I would suspect > it's for performance reasons. > > > > > > Josh > > > > > > -----Original Message----- > > From: devel-boun...@open-mpi.org [mailto:devel-boun...@open-mpi.org] On > Behalf Of Jeff Squyres (jsquyres) > > Sent: Wednesday, February 20, 2013 4:35 PM > > To: <de...@open-mpi.org> > > Subject: [OMPI devel] openib fragment alignment > > Importance: High > > > > Arrgh. I think you're going to make me eat my words ( > http://www.open-mpi.org/community/lists/devel/2013/02/12143.php). > > > > I just recently lost my access to InfiniBand test gear, so I can't test > this myself. Hypothetically, it should be fine. But throwing in an > untested change literally right before a release without IB vendor say-so > really, really gives me pause... > > > > Mellanox? > > > > > > On Feb 20, 2013, at 4:27 PM, Open MPI <b...@open-mpi.org> wrote: > > > > > #3519: Move r28083 to v1.6 branch > > > -----------------------------------+-------------------------- > > > Reporter: hjelmn | Owner: hjelmn > > > Type: changeset move request | Status: new > > > Priority: major | Milestone: Open MPI 1.6 > > > Version: trunk | > > > -----------------------------------+-------------------------- > > > (In [28083]) btl/openib: don't align fragments on 2 byte boundaries > > > (changed to 8) > > > > > > cmr:v1.6,v1.7 > > > > > > -- > > > Ticket URL: <https://svn.open-mpi.org/trac/ompi/ticket/3519> > > > Open MPI <http://www.open-mpi.org/> > > > > > > _______________________________________________ > > > bugs mailing list > > > b...@open-mpi.org > > > http://www.open-mpi.org/mailman/listinfo.cgi/bugs > > > > > > -- > > Jeff Squyres > > jsquy...@cisco.com > > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > > > > > _______________________________________________ > > devel mailing list > > de...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/devel > > > > _______________________________________________ > > devel mailing list > > de...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/devel > _______________________________________________ > devel mailing list > de...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/devel > -- Paul H. Hargrove phhargr...@lbl.gov Future Technologies Group Computer and Data Sciences Department Tel: +1-510-495-2352 Lawrence Berkeley National Laboratory Fax: +1-510-486-6900
