diff --git a/doc/src/Build_settings.rst b/doc/src/Build_settings.rst index 7576cae3eb..33b0508fe9 100644 --- a/doc/src/Build_settings.rst +++ b/doc/src/Build_settings.rst @@ -51,14 +51,18 @@ LAMMPS can use them if they are available on your system. .. code-block:: bash -D FFT=value # FFTW3 or MKL or KISS, default is FFTW3 if found, else KISS + -D FFT_KOKKOS=value # FFTW3 or MKL or KISS or CUFFT or HIPFFT, default is KISS -D FFT_SINGLE=value # yes or no (default), no = double precision -D FFT_PACK=value # array (default) or pointer or memcpy .. note:: - The values for the FFT variable must be in upper-case. This is - an exception to the rule that all CMake variables can be specified - with lower-case values. + When the Kokkos variant of a package is compiled and selected at run time, + the FFT library selected by the FFT_KOKKOS variable applies. Otherwise, + the FFT library selected by the FFT variable applies. + The same FFT settings apply to both. FFT_KOKKOS must be compatible with the + Kokkos backend - for example, when using the CUDA backend of Kokkos, + you must use either CUFFT or KISS. Usually these settings are all that is needed. If FFTW3 is selected, then CMake will try to detect, if threaded FFTW @@ -87,6 +91,8 @@ LAMMPS can use them if they are available on your system. FFT_INC = -DFFT_FFTW3 # -DFFT_FFTW3, -DFFT_FFTW (same as -DFFT_FFTW3), -DFFT_MKL, or -DFFT_KISS # default is KISS if not specified + FFT_INC = -DFFT_KOKKOS_CUFFT # -DFFT_KOKKOS_{FFTW,FFTW3,MKL,CUFFT,HIPFFT,KISS} + # default is KISS if not specified FFT_INC = -DFFT_SINGLE # do not specify for double precision FFT_INC = -DFFT_FFTW_THREADS # enable using threaded FFTW3 libraries FFT_INC = -DFFT_MKL_THREADS # enable using threaded FFTs with MKL libraries @@ -97,6 +103,8 @@ LAMMPS can use them if they are available on your system. FFT_INC = -I/usr/local/include FFT_PATH = -L/usr/local/lib + FFT_LIB = -lhipfft # hipFFT either precision + FFT_LIB = -lcufft # cuFFT either precision FFT_LIB = -lfftw3 # FFTW3 double precision FFT_LIB = -lfftw3 -lfftw3_omp # FFTW3 double precision with threads (needs -DFFT_FFTW_THREADS) FFT_LIB = -lfftw3 -lfftw3f # FFTW3 single precision @@ -141,6 +149,10 @@ The Intel MKL math library is part of the Intel compiler suite. It can be used with the Intel or GNU compiler (see the ``FFT_LIB`` setting above). +The CUFFT and HIPFFT FFT libraries are packaged with NVIDIA's CUDA and AMD's +HIP installations, respectively. These FFT libraries require the Kokkos acceleration +package to be enabled and the Kokkos backend to be GPU-resident (ie, HIP or CUDA). + Performing 3d FFTs in parallel can be time-consuming due to data access and required communication. This cost can be reduced by performing single-precision FFTs instead of double precision. Single precision diff --git a/doc/src/Howto_cmake.rst b/doc/src/Howto_cmake.rst index 42324cf2f1..8b710d1065 100644 --- a/doc/src/Howto_cmake.rst +++ b/doc/src/Howto_cmake.rst @@ -349,6 +349,8 @@ Some common LAMMPS specific variables - when set to ``name`` the LAMMPS executable and library will be called ``lmp_name`` and ``liblammps_name.a`` * - ``FFT`` - select which FFT library to use: ``FFTW3``, ``MKL``, ``KISS`` (default, unless FFTW3 is found) + * - ``FFT_KOKKOS`` + - select which FFT library to use in Kokkos-enabled styles: ``FFTW3``, ``MKL``, ``HIPFFT``, ``CUFFT``, ``KISS`` (default) * - ``FFT_SINGLE`` - select whether to use single precision FFTs (default: ``off``) * - ``WITH_JPEG`` diff --git a/doc/src/kspace_style.rst b/doc/src/kspace_style.rst index 38a6fce375..78d7380c01 100644 --- a/doc/src/kspace_style.rst +++ b/doc/src/kspace_style.rst @@ -450,7 +450,10 @@ relative RMS error. For the KOKKOS package, the *pppm/kk* style performs charge assignment and force interpolation calculations, along with the FFTs themselves, on the GPU or (optionally) threaded on the CPU when - using OpenMP and FFTW3. + using OpenMP and FFTW3. The specific FFT library is selected using + the FFT_KOKKOS CMake parameter. See the + :doc:`Build settings ` doc page for how to select a + 3rd-party FFT library. ----------