Another version of the atomic patch. Paul has tested it on a bunch of platforms. At this point we have confirmation from all architectures except SPARC (v8+ and v9).
George.
atomics.patch
Description: Binary data
On Jul 31, 2014, at 19:13 , George Bosilca <bosi...@icl.utk.edu> wrote: > All, > > Here is the patch that change the meaning of the atomics to make them always > return the previous value (similar to sync_fetch_and_<*>). I tested this with > the following atomics: OS X, gcc style intrinsics and AMD64. > > I did not change the base assembly files used when GCC style assembly > operations are not supported. If someone feels like fixing them, feel free. > > Paul, I know you have a pretty diverse range computers. Can you try to > compile and run a “make check” with the following patch? > > George. > > <atomics.patch> > > On Jul 30, 2014, at 15:21 , Nathan Hjelm <hje...@lanl.gov> wrote: > >> >> That is what I would prefer. I was trying to not disturb things too >> much :). Please bring the changes over! >> >> -Nathan >> >> On Wed, Jul 30, 2014 at 03:18:44PM -0400, George Bosilca wrote: >>> Why do you want to add new versions? This will lead to having two, almost >>> identical, sets of atomics that are conceptually equivalent but different >>> in terms of code. And we will have to maintained both! >>> I did a similar change in a fork of OPAL in another project but instead of >>> adding another flavor of atomics, I completely replaced the available ones >>> with a set returning the old value. I can bring the code over. >>> George. >>> >>> On Tue, Jul 29, 2014 at 5:29 PM, Paul Hargrove <phhargr...@lbl.gov> wrote: >>> >>> On Tue, Jul 29, 2014 at 2:10 PM, Nathan Hjelm <hje...@lanl.gov> wrote: >>> >>> Is there a reason why the >>> current implementations of opal atomics (add, cmpset) do not return >>> the >>> old value? >>> >>> Because some CPUs don't implement such an atomic instruction? >>> >>> On any CPU one *can* certainly synthesize the desired operation with an >>> added read before the compare-and-swap to return a value that was >>> present at some time before a failed cmpset. That is almost certainly >>> sufficient for your purposes. However, the added load makes it >>> (marginally) more expensive on some CPUs that only have the native >>> equivalent of gcc's __sync_bool_compare_and_swap(). >>> >>> -Paul >>> -- >>> 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 >>> _______________________________________________ >>> 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/2014/07/15328.php >> >>> _______________________________________________ >>> 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/2014/07/15369.php >> >> _______________________________________________ >> 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/2014/07/15370.php >
