search

NCAR / ccpp-physics

GFS physics for CCPP
Other
56 stars 145 forks source link

CMake error: include could not find detect_openmp #986

Closed michalakes closed 1 year ago

michalakes commented 1 year ago

Description

Compiling ccppV6 as part of NEPTUNE build, we now get an error:

CMake Error at CMakeLists.txt:116 (include)
  include could not find load file:
    detect_openmp

I don't think we had this problem with ccpp v5

Steps to Reproduce

I'm not sure what the non-NEPTUNE to reproduce this is, but it's happening as a result of the command:


    ./build_ccpp.sh sandy /users/michalakes/neptune_atmos "DEBUG=N           \
                    OPENMP=Y HYBRID=N STATIC=Y 32BIT=N" "NO" "NO"

in our NEPTUNE build.

Additional Context

Please provide any relevant information about your setup. This is important in case the issue is not reproducible except for under certain conditions.

Output

I'm attaching a screenshot of the line 116 in CMakeLists that's referred to in the error message, above. screenshot

dustinswales commented 1 year ago

@michalakes The snippet of code above from CMakeLists.txt appears to be from the v5 release? CMakeLists has been updated for CCPP v6.

michalakes commented 1 year ago

@michalakes The snippet of code above from CMakeLists.txt appears to be from the v5 release? CMakeLists has been updated for CCPP v6.

Thanks, Dustin. I think with NEPTUNE we've got a V6/V5 chimera at the CMake level. I found a workaround, for now, that involved recovering the errant detect_openmp.cmake from V5 and adding it back to our patchwork around V6. I think it's our problem so this issue can be closed, but before I do that, a follow up, please:

Background: We need for CCPP to be compiled without OpenMP, even when NEPTUNE is compiled with OpenMP. For the Intel compiler, we do need the -auto flag but not -qopenmp. That's because we have the threading at a higher level, above the calls to CCPP. We expect the code inside CCPP to run single threaded on each higher-level thread that it's called. The problem we ran into in V6 was that CMake was seeing OPENMP set to true in the environment and then compiling it with -qopenmp. After a couple days of hunting I see that we had put a line into the V5 detect_openmp.cmake that specifically omitted -qopenmp from the Fortran flags. When detect_openmp.cmake went missing, so did that work-around.

So the questions:

  1. Does the new V6 CMake apparatus have a way of saying not to compile with OpenMP flags but with -auto?
  2. Does CCPP physics actually build under the Intel when -qopenmp is specified? I see cascades of error messages having to do with !$omp target directives.

If you prefer, I could close the issue now and we could discuss this offline. Thanks for your reply!

John

michalakes commented 1 year ago

I am closing this issue. We found a fix that does not require the detect_openmp.cmake file or any other modifications to submodules that NEPTUNE gets from CCPP.