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How do you set configure.ac (autoconf) in my own application to auto-discover LAPACK, ATLAS, OpenBLAS, and KMP? – CentOS

I’m new to autoconf as well as linear algebra libraries. So far as I can tell, LAPACK, ATLAS, OpenBLAS, and KML can co-exist on the filesystem but you can only use one of the libraries at link-time and I would like to let ./configure choose whatever is available or let the user select it with ./configure –something.

Different distributions put things in different directories and it would be nice if autoconf can figure that out.

  • LAPACK is -llapack
  • ATLAS is -lsatlas -L /usr/lib64/atlas # CentOS
    • or -ltatlas for the threaded version
  • OpenBLAS is -lopenblas
    • or -lopenblasp for the pthread version
    • or -lopenblaso for the OpenMP version

Questions:

  • Is there already a "proper" way to do this with AC_ macros?
    • Do AC_ macros already exist for these libraries?
  • How would you setup configure.ac to find the first available library that is installed but default to threaded ATLAS if available?
  • How would you setup configure.ac to allow the user to select, for example, the OpenMP version of OpenBLAS?
    • Would you use an option like –with-openblas-openmp ?
    • What would the configure.ac code look like?

Thank you for your help!

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    The PSFEX package does this, see https://github.com/astromatic/psfex/blob/master/configure.ac#L285 :

    # Provide special options for INTEL MKL and force the use of icc
AC_MSG_CHECKING([whether INTEL's MKL is enabled])
AC_ARG_ENABLE(mkl,
    [AS_HELP_STRING([--enable-mkl],
    [Use INTEL's MKL for solvers and FFTs (default = no)])],
        enable_icc="yes"
        CC="icc"
    AC_MSG_RESULT([yes]),
    AC_MSG_RESULT([no]))
    
# Provide special options for ATLAS
AC_ARG_WITH(atlas-libdir,
    [AS_HELP_STRING([--with-atlas-libdir=<ATLAS library path>],
    [Provide an alternative path to the ATLAS library])])
AC_ARG_WITH(atlas-incdir,
    [AS_HELP_STRING([--with-atlas-incdir=<ATLAS header dir>],
    [Provide an alternative path to the ATLAS header directory])])
    
# Provide special options for OpenBLAS
AC_MSG_CHECKING([whether OpenBLAS is enabled])
AC_ARG_ENABLE(openblas,
    [AS_HELP_STRING([--enable-openblas],
    [Use the OpenBLAS library instead of ATLAS (default = no)])],
    AC_MSG_RESULT([yes]),
    AC_MSG_RESULT([no]))
AC_ARG_WITH(openblas-libdir,
    [AS_HELP_STRING([--with-openblas-libdir=<OpenBLAS library path>],
    [Provide an alternative path to the OpenBLAS library])])
AC_ARG_WITH(openblas-incdir,
    [AS_HELP_STRING([--with-openblas-incdir=<OpenBLAS header dir>],
    [Provide an alternative path to the OpenBLAS header directory])])


############ handle the INTEL MKL library (FFTW + LAPACKe) ###########
if test "$enable_mkl" = "yes"; then
  convlibs="${srcdir}/../src/wcs/libwcs_c.a,${srcdir}/../src/levmar/liblevmar.a"
  ACX_MKL($with_mkl_dir,no,$enable_best_link,$convlibs)
  AC_MSG_CHECKING([for the INTEL MKL])
  if test "$MKL_WARN" == ""; then
    AC_MSG_RESULT([yes])
  else
    AC_MSG_RESULT([no])
    AC_MSG_WARN([$MKL_WARN])
  fi
  AM_CFLAGS="$AM_CFLAGS $MKL_CFLAGS "
  AM_LDFLAGS="$AM_LDFLAGS $MKL_LDFLAGS "
  LIBS="$LIBS $MKL_LIBS"

############ Select either openblas or atlas ############
else    
  if test "x$enable_openblas" = "xyes"; then
    ######## Handle the OpenBLAS library (linear algebra: BLAS + LAPACKe) ########
    ACX_OPENBLAS($with_openblas_libdir, $with_openblas_incdir, $use_pthreads, no,
      [
        AM_CFLAGS="$AM_CFLAGS $OPENBLAS_CFLAGS "
        AM_LDFLAGS="$AM_LDFLAGS $OPENBLAS_LDFLAGS "
        LIBS="$OPENBLAS_LIBS $LIBS"
        if test "$OPENBLAS_WARN" != ""; then
          AC_MSG_WARN([$OPENBLAS_WARN])
        fi
      ],
      AC_MSG_ERROR([$OPENBLAS_ERROR Exiting.])
    )

  else
    ######### handle the ATLAS library (linear algebra: BLAS + cLAPACK) ##########
    ACX_ATLAS($with_atlas_libdir, $with_atlas_incdir, $use_pthreads,
      [
        [LIBS="$ATLAS_LIBS $LIBS"]
        if test "$ATLAS_WARN" != ""; then
      AC_MSG_WARN([$ATLAS_WARN])
    fi
      ],
      AC_MSG_ERROR([$ATLAS_ERROR Exiting. You could try --enable-openblas if Atlas is unavailable.])
    )
  fi
fi

AC_ARG_WITH([lapack],
  [AS_HELP_STRING([--without-lapack],
  [disable support for lapack])],
  [],
  [with_lapack=no])

LIBLAPACK=
  AS_IF([test "x$with_lapack" != xno],
  [
    AX_BLAS([], [AC_MSG_ERROR([BLAS library not found])])
    AX_LAPACK([], [AC_MSG_ERROR([LAPACK library not found])])

    LIBS="$LAPACK_LIBS $BLAS_LIBS $LIBS $FLIBS"
    AC_CHECK_LIB(
    [lapack], [zgetrf], 
    [AC_SUBST([LIBLAPACK], ["$LAPACK_LIBS $BLAS_LIBS $LIBS $FLIBS"]) AC_DEFINE([LAPACK], [1], [Define if you have liblapack])],
    [AC_MSG_FAILURE([lapack library test failed (--without-lapack to disable)])],
    [])
  ])

    Also note that you will need their macro libraries (available here) which are too big to paste into the answer:

    • acx_mkl.m4
    • acx_atlas.m4
    • acx_openblas.m4

  2. 0

    You could use dlopen() to dynamically load the library functions that you need. Then you needn’t worry about configure.ac settings since your application would auto-detect the available libraries at runtime.

    The xnec2c antenna simulator does this using their mathlib.c and mathlib.h implementations for the zgetrf() and zgetrs() calls. It could be extended to support other linear algebra calls as well. Maybe someone will write a unified linear algebra meta-library to dynamically back all the various implementations in one front-end library! (If you do, be sure to tell the xnec2c maintainer so they might use your changes.)

    The mathlib.c file contains a typedef struct mathlib_t that defines the library names, shared object path, and function prefix for each library. It supports shared object library names for autodetecting Ubuntu/Debian, CentOS/RHEL, and openSUSE at runtime; other distributions more-or-less use the same library names, so, effectively, far more than just the above listed distributions are supported:

    static mathlib_t mathlibs[] = {
    {.type = MATHLIB_ATLAS, .lib = "libtatlas.so.3", .name = "ATLAS, Threaded", .f_prefix = "clapack_"},
    {.type = MATHLIB_OPENBLAS, .lib = "libopenblaso.so", .name = "OpenBLAS+LAPACKe, OpenMP", .f_prefix = "LAPACKE_"},
}

    Note that ATLAS and OpenBLAS use different function prefixes: clapack_ vs LAPACKE_; so having a wrapper around the different libraries is useful. Xnec2c supports ATLAS, OpenBLAS+LAPACK, and Intel MKL.

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