Hi Jerry, I can not compile the example from Toon. I get two issues:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120843 and https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120847 Can you reproduce? - Andre On Thu, 26 Jun 2025 16:49:59 -0700 Jerry Delisle <jvdelis...@gmail.com> wrote: > Toon, thank you! I will give it a try here so we can have some data points. > > Jerry > > On Thu, Jun 26, 2025, 2:08 PM Toon Moene <t...@moene.org> wrote: > > > On 6/26/25 21:34, Thomas Koenig wrote: > > > > > Am 26.06.25 um 10:15 schrieb Andre Vehreschild: > > > > >> Hi Thomas, > > >> > > >>> I have a few questions. > > >>> > > >>> First, I see that your patch series does not use gfortran's descriptors > > >>> for accessing coarrays via shared memory, as the original work by > > >>> Nicolas did. Can you comment on that? > > >> > > >> The ABI for invoking coarray functionality is sufficient for doing the > > >> job. > > >> Modifying the compiler to access coarrays directly, i.e., having > > >> implementation > > >> detail on a certain library in the compiler did not appeal to me. > > >> Furthermore > > >> has the new library in conjunction with the other library available the > > >> potential to get to a stable and maintained ABI. Having another ABI in > > >> the > > >> compiler would have lead to two badly maintained ones (in my opinion). I > > >> therefore decided to just have one ABI and figured that all that is > > >> needed can > > >> be done in a library. This also allows link-time polymorphism. And > > >> last but not > > >> least, there is a major rework on the array descriptor going on and > > >> that would > > >> have had the potential to conflict with my work. > > > > > > We are very probably not going to get performance out of it that is > > > comparable with the original design; I would be quite surprised if it > > > was appreciably better than using shared memory MPI, and in that > > > case I don't see an advantage of your patch over a better wrapper. > > > > When I learned about the "Koenig" implementation of "native coarrays" in > > 2018 (as they called it at that time, and I since noticed also Intel > > calls it), I wrote a "mock weather forecasting program" using coarrays > > to test it against the then working implementation of OpenCoarrays using > > MPI calls. > > > > You can find the program here: https://moene.org/~toon/random-weather > > > > [ note that I improved on this program until early in 2021. ] > > > > When I compared the run time of the two implementations with the same > > input parameters on a 128 Gbyte RAM Intel machine, the "native" > > implementation was around a factor of 5 faster. Of course, the > > OpenCoarrays based MPI implementation (using OpenMPI) used shared memory > > MPI (which OpenMPI calls "vader" for reasons that escape me). > > > > So I am certainly interested to compare Andre's implementation against > > OpenCoarrays. > > > > Kind regards, > > > > -- > > Toon Moene - e-mail: t...@moene.org - phone: +31 346 214290 > > Saturnushof 14, 3738 XG Maartensdijk, The Netherlands > > -- Andre Vehreschild * Email: vehre ad gmx dot de
