On Thu, 4 Apr 2024, Frank Bramkamp wrote: > Dear PETSC Team, > > I found the following problem: > I compile petsc 3.20.5 with Nvidia compiler 23.7. > > > I use a pretty standard configuration, including > > --with-cc=mpicc --with-cxx=mpicxx --with-fc=mpifort COPTFLAGS="-O2 -g" > CXXOPTFLAGS="-O2 -g" FOPTFLAGS="-O2 -g" --with-debugging=0 --with-log=1 > --download-fblaslapack --with-cuda=0 > > I exclude cuda, since I was not sure if the problem was cuda related.
Can you try using (to exclude cuda): --with-cudac=0 > > > The problem is now, if I have s simple fortran program where I link the petsc > library, but I actually do not use petsc in that program > (Just for testing). I want to use OpenACC directives in my program, e.g. > !$acc parallel loop . > The problem is now, as soon I link with the petsc library, the openacc > commands do not work anymore. > It seems that openacc is not initialised and hence it cannot find a GPU. > > The problem seems that you link with -lnvc. > In “petscvariables” => PETSC_WITH_EXTERNAL_LIB you include “-lnvc”. > If I take this out, then openacc works. With “-lnvc” something gets messed up. > > The problem is also discussed here: > https://urldefense.us/v3/__https://forums.developer.nvidia.com/t/failed-cuda-device-detection-when-explicitly-linking-libnvc/203225/1__;!!G_uCfscf7eWS!dlXNyKBzSbximQ13OXxwO506OF71yRM_H5KEnarqXE75D6Vg-ePZr2u6SJ5V3YpRETatvb9pMOUVmpyN0-19SFlbug$ > > <https://urldefense.us/v3/__https://forums.developer.nvidia.com/t/failed-cuda-device-detection-when-explicitly-linking-libnvc/203225/1__;!!G_uCfscf7eWS!dlXNyKBzSbximQ13OXxwO506OF71yRM_H5KEnarqXE75D6Vg-ePZr2u6SJ5V3YpRETatvb9pMOUVmpyN0-19SFlbug$ > > > > My understanding is that libnvc is more a runtime library that does not need > to be included by the linker. > Not sure if there is a specific reason to include libnvc (I am not so > familiar what this library does). > > If I take out -lnvc from “petscvariables”, then my program with openacc works > as expected. I did not try any more realistic program that includes petsc. > > > > 2) > When compiling petsc with cuda support, I also found that in the petsc > library the library libnvJitLink.so.12 > Is not found. On my system this library is in $CUDA_ROOT/lib64 > I am not sure where this library is on your system ?! Hm - good if you can send configure.log for this. configure attempts '$CC -v' to determine the link libraries to get c/c++/fortran compatibility libraries. But it can grab other libraries that the compilers are using internally here. To avoid this - you can explicitly list these libraries to configure. For ex: for gcc/g++/gfortran ./configure CC=gcc CXX=g++ FC=gfortran LIBS="-lgfortran -lstdc++" Satish > > > Thanks a lot, Frank Bramkamp > > > > > > > > > > > >
