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FFTW / fftw3

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Need help in building fftw . #273

Closed mohit9638iitk closed 2 years ago

mohit9638iitk commented 2 years ago

I want to overload the MPI_Sendrecv() function of fftw. I have one header file named as "lib.h" and code in file named as "lib.c".

For simple example (say mpi_3d_fftw3.cpp) I do command line compilation ;-

  1. $ mpicc -c -Wall -Werror -fpic lib.c (this create a executable "lib.o").
  2. $mpicc mpi_3d_fftw.cpp lib.o -o fftw_non_block -lfftw3_mpi -lfftw3 -lm

So, basically mpi_3d_fftw.cpp will call fftw_execute and internally it uses MPI_Sendrecv() for communication purpose. By compiling with lib.o executable, fftw uses my version of MPI_Sendrecv().

I want to know how to link my library with fftw so that I do not have to compile with my executable for every code.

Please help me in doing this thing.

hominhquan commented 2 years ago

There are two possible solutions AFAIK:

  1. Dynamic linking (most often): You can compile your code to a separate libmy_mpi.so and use the LD_PRELOAD trick.
  2. Static linking: the best way IMO is to compile FFTW with -D MPI_Sendrecv=MPI_Sendrecv_custom and ensure to have the MPI_Sendrecv_custom() symbol in your libmy_mpi.a
mohit9638iitk commented 2 years ago

Thanks @hominhquan ,it has helped me a lot.