> - I guess you have your MPI implementaion w/ ummunotify, right? Yes, Jeff Squyres (cc'ed) has an Open MPI prototype (mercurial tree at http://bitbucket.org/jsquyres/ummunot/).
> - I guess you have test sevaral pattern, right? > if so, can we see your test result? Open MPI has a pretty extensive automated test fabric -- I don't have a link handy but I believe all the tests that pass with unmodified Open MPI currently still pass with ummunotify. Maybe Jeff has a link. > - I think you can explain your MPI advantage/disadvantage against > current OpenMPI (or mpich et al). The advantage is as Jeff explained in his blog post (http://blogs.cisco.com/ciscotalk/performance/comments/better_linux_memory_tracking/), namely the performance improvement of memory registration caching without the reliability problems caused by previous approaches to caching such as trying to hook malloc etc (which are fragile because the great diversity of MPI-using codes find ways to mess up all previous userspace-only approaches). > - I guess your patch dramatically improve MPI implementaion, but > it's not free. it request some limitation to MPI application, right? Not that I know of, beyond already existing limitations. > - I imagine multi thread and fork. Is there another linmitaion? There are no new limitations on multi-threaded codes or on use of fork that I know of. Of course, buggy code that does something like passing a buffer to MPI in one thread and then freeing that buffer from another thread before MPI is done with it is still buggy; but ummunotify actually increases the ability of the MPI implementation to detect such bugs and give useful diagnostic information. > - In past discuttion, you said ummunotify user should not use > multi threading. you also think user should not fork? I don't recall where I said ummunotify users should not be multithreaded. I don't know of any problem with that. Also code using ummunotify can fork -- ummunotify simply does not fix issues with copy-on-write for buffers that are in use, just as it does not fix multithreaded code that has a race between using a buffer and freeing the same buffer. Hope this clarifies things. - Roland _______________________________________________ general mailing list general@lists.openfabrics.org http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general