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CUDA 5.0 separate compilation of library with cmake

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情话喂你
情话喂你 2020-12-05 11:59

The buildtime of my cuda library is increasing and so I thought that separate compilation introduced in CUDA 5.0 might help me. I couldn\'t figure out how to achieve separat

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  • 心在旅途
    2020-12-05 12:24

    EDIT (2016-03-15): Yes, it is confirmed as a bug in FindCUDA: https://cmake.org/Bug/view.php?id=15157

    TL;DR: This seems to be a bug in FindCUDA, which makes objects lose info on external definitions before the final linking.

    The problem is that, even if separable compilation is enabled, a linking step is still performed for all the targets individually before the final linking.

    For instance, I have module.cu with:

    #include "module.h"
#include <cstdio>

double arr[10] = {1,2,3,4,5,6,7,8,9,10};
__constant__ double carr[10];

void init_carr() {
  cudaMemcpyToSymbol(carr,arr,10*sizeof(double));
}

__global__ void pkernel() {
  printf("(pkernel) carr[%d]=%g\n",threadIdx.x,carr[threadIdx.x]);
}

void print_carr() {
  printf("in print_carr\n");
  pkernel<<<1,10>>>();
}

    and module.h with:

    extern __constant__ double carr[10];
extern double arr[10];

void print_carr();
void init_carr();

    and finally main.cu with:

    #include "module.h"

#include <cstdio>

__global__ void kernel() {
  printf("(kernel) carr[%d]=%g\n",threadIdx.x,carr[threadIdx.x]);
}


int main(int argc, char *argv[]) {
  printf("arr: %g %g %g ..\n",arr[0],arr[1],arr[2]);

  kernel<<<1,10>>>();
  cudaDeviceSynchronize();
  print_carr();
  cudaDeviceSynchronize();
  init_carr();
  cudaDeviceSynchronize();
  kernel<<<1,10>>>();
  cudaDeviceSynchronize();
  print_carr();
  cudaDeviceSynchronize();

  return 0;
}

    This then works fine with the following Makefile:

    NVCC=nvcc
NVCCFLAGS=-arch=sm_20
LIB=libmodule.a
OBJS=module.o main.o
PROG=extern

$(PROG): main.o libmodule.a
    $(NVCC) $(NVCCFLAGS) -o $@ $^

%.o: %.cu
    $(NVCC) $(NVCCFLAGS) -dc -c -o $@ $^

$(LIB): module.o
    ar cr $@ $^

clean:
    $(RM) $(PROG) $(OBJS) $(LIB)

    But then I try to use the following CMakeLists.txt:

    CMAKE_MINIMUM_REQUIRED(VERSION 2.8.8)

PROJECT(extern)

FIND_PACKAGE(CUDA REQUIRED)
SET(CUDA_SEPARABLE_COMPILATION ON)

SITE_NAME(HOSTNAME)

SET(CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS} -arch=sm_20)

cuda_add_library(module module.cu)

CUDA_ADD_EXECUTABLE(extern main.cu)
TARGET_LINK_LIBRARIES(extern module)

    When then compiling, what then happens is that the following:

    $ cmake ..
-- The C compiler identification is GNU 4.9.2
...
$ make VERBOSE=1
...
[ 25%] Building NVCC (Device) object CMakeFiles/module.dir//./module_generated_module.cu.o
...
-- Generating <...>/build/CMakeFiles/module.dir//./module_generated_module.cu.o
/usr/local/cuda/bin/nvcc <...>/module.cu -dc -o <...>/build/CMakeFiles/module.dir//./module_generated_module.cu.o -ccbin /usr/bin/cc -m64 -Xcompiler ,\"-g\" -arch=sm_20 -DNVCC -I/usr/local/cuda/include
[ 50%] Building NVCC intermediate link file CMakeFiles/module.dir/./module_intermediate_link.o
/usr/local/cuda/bin/nvcc -arch=sm_20 -m64 -ccbin "/usr/bin/cc" -dlink <...>/build/CMakeFiles/module.dir//./module_generated_module.cu.o -o <...>/build/CMakeFiles/module.dir/./module_intermediate_link.o
...
/usr/bin/ar cr libmodule.a  CMakeFiles/module.dir/./module_generated_module.cu.o CMakeFiles/module.dir/./module_intermediate_link.o
/usr/bin/ranlib libmodule.a
...
[ 50%] Built target module
[ 75%] Building NVCC (Device) object CMakeFiles/extern.dir//./extern_generated_main.cu.o
...
-- Generating <...>/build/CMakeFiles/extern.dir//./extern_generated_main.cu.o
/usr/local/cuda/bin/nvcc <...>/main.cu -dc -o <...>/build/CMakeFiles/extern.dir//./extern_generated_main.cu.o -ccbin /usr/bin/cc -m64 -Xcompiler ,\"-g\" -arch=sm_20 -DNVCC -I/usr/local/cuda/include -I/usr/local/cuda/include
...
[100%] Building NVCC intermediate link file CMakeFiles/extern.dir/./extern_intermediate_link.o
/usr/local/cuda/bin/nvcc -arch=sm_20 -m64 -ccbin "/usr/bin/cc" -dlink <...>/build/CMakeFiles/extern.dir//./extern_generated_main.cu.o -o <...>/build/CMakeFiles/extern.dir/./extern_intermediate_link.o
nvlink error   : Undefined reference to 'carr' in '<...>/build/CMakeFiles/extern.dir//./extern_generated_main.cu.o'

    Clearly, the problem are the nvcc -dlink obj.o -o obj_intermediate_link.o lines. Then, I guess, the info on external definitions are lost. So, the question is, it is possible to make CMake/FindCUDA not do this extra linking step?

    Otherwise, I would argue that this is a bug. Do you agree? I can file a bug report with CMake.

    0 讨论(0)
  • 失恋的感觉
    2020-12-05 12:39

    I finally got it running ;)

    In Addition to the answer of @PHD and my comment on it I modified: set(BUILD_SHARED_LIBS OFF) in my CMakeLists.txt since shared libs are not supported for separate compilation according to the nvcc manually v5.0 page 40.

    In addition to that use the latest rev (1223) from the repository instead of rev 1221. I contacted the developer and he fixed some issue blocking this. This revision doesn't set the nvcc -arch=sm_xx flag correctly, so I added this manually for my project and informed the developer of FindCUDA.cmake. So this might get fixed in the future.

    Don't forget to get cmake > 2.8.10 for this to work.

    Hope this helps anyone but me ;)

    Here is my CMakeLists.txt:

    #Required for CUDA-Check
cmake_minimum_required(VERSION 2.8.10)

project(gpulib)

set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/CMake/cuda" ${CMAKE_MODULE_PATH})
# ============================================
# === Target
# ============================================
file(GLOB_RECURSE gpuacc_SRCS "*.cu")
include_directories(.)

# ---------------------------------------
# Find Cuda
find_package(CUDA REQUIRED)

set(CUDA_ATTACH_VS_BUILD_RULE_TO_CUDA_FILE ON)

set(BUILD_SHARED_LIBS OFF)

set(CUDA_SEPARABLE_COMPILATION ON)
#list(APPEND CUDA_NVCC_FLAGS -arch=sm_20)

set(LIB_NAME "gpuacceleration")
cuda_add_library(${LIB_NAME}
  ${gpuacc_SRCS} 
  OPTIONS -DSTUFF="blah blah"
  RELEASE -DNDEBUG
  DEBUG -g -DDEBUG
)

set(PUBLIC_HEADERS "myheader1.h;myheader2.h")

INSTALL(FILES ${PUBLIC_HEADERS} DESTINATION include)
INSTALL(FILES "${CMAKE_BINARY_DIR}/src/lib${LIB_NAME}.a" DESTINATION lib)

    EDIT: this is not working! The problem is that there are undefined references to all cuda functions (eg. cudaMalloc) when linking the generated library when building a executable in the main project.

    Still working on it

    0 讨论(0)
  • 暗喜
    2020-12-05 12:42

    I couldn't make it works using CUDA_ADD_EXECUTABLE so I created a function that makes a custom target to do so.

    function(add_cuda_exe_lib name files libraries is_lib)
    set (obj_list)
    foreach(file ${files})
        add_custom_command(
            OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${file}.o
            DEPENDS ${file} 
            COMMAND ${CMAKE_COMMAND} -E cmake_echo_color --blue "Building NVCC Device object ${CMAKE_CURRENT_SOURCE_DIR}/${file}"
            COMMAND ${CUDA_NVCC_EXECUTABLE} ${CUDA_NVCC_FLAGS} -dc "${CMAKE_CURRENT_SOURCE_DIR}/${file}" -o "${CMAKE_CURRENT_BINARY_DIR}/${file}.o"
            COMMENT "Building ${CMAKE_CURRENT_SOURCE_DIR}/${file}"
            VERBATIM
        )

        LIST(APPEND obj_list ${CMAKE_CURRENT_BINARY_DIR}/${file}.o)
    endforeach()

    set (lib_list)
    LIST(APPEND lib_list "-lcudadevrt")
    foreach(library_name ${libraries})
        LIST(APPEND lib_list "-l${library_name}")
    endforeach()

    set (flags ${CUDA_NVCC_FLAGS})
    if (is_lib)
        LIST(APPEND flags "-dlink")
        set (obj_name "${CMAKE_CURRENT_BINARY_DIR}/${name}.so")
    else()
        set (obj_name "${CMAKE_CURRENT_BINARY_DIR}/${name}")
    endif()

    add_custom_target(${name} ALL 
        COMMAND ${CMAKE_COMMAND} -E cmake_echo_color --red "Linking CXX executable ${name}"
        COMMAND ${CUDA_NVCC_EXECUTABLE} ${flags} ${obj_list} ${lib_list} -o ${obj_name}
        DEPENDS ${obj_list}
        COMMENT "Linking ${name}"
    )
endfunction()

function(add_cuda_exe name files libraries)
    add_cuda_exe_lib(${name} "${files}" "${libraries}" OFF)
endfunction()

function(add_cuda_lib name files libraries)
    add_cuda_exe_lib(${name} "${files}" "${libraries}" ON)
endfunction()

    Now, to generate a lib, just use:

    add_cuda_lib(testar "devicemanager.cu;blub.cu" "")

    Or this to generate an executable:

    add_cuda_exe(testar "devicemanager.cu;blub.cu" "")

    The last param is a list of libs to be attached.

    I hope it helps.

    0 讨论(0)
  • 陌清茗
    2020-12-05 12:48

    Tested it with nvcc version:

    nvcc: NVIDIA (R) Cuda compiler driver Copyright (c) 2005-2012 NVIDIA
Corporation Built on Fri_Sep_21_17:28:58_PDT_2012 Cuda compilation
tools, release 5.0, V0.2.1221

    and svn revision:

    URL: https://gforge.sci.utah.edu/svn/findcuda/trunk
Repository Root: https://gforge.sci.utah.edu/svn/findcuda
Repository UUID: 81322f20-870f-0410-845c-a4cd4664c908
Revision: 1221
Node Kind: directory
Schedule: normal
Last Changed Rev: 1221
Last Changed Date: 2013-01-28 22:31:07 +0100 (Mon, 28 Jan 2013)

    In this example includes following classes:

    • lib.h / lib.cu
    • kernel.h / kernel.cu

    kernel.cu contains a simple CUDA kernel and a class with a public method to call the CUDA kernel. The class lib contains an instance of the class kernel and a method calling the public method of class kernel.

    Following CMakeLists.txt works with this configuration:

    cmake_minimum_required(VERSION 2.6.2)

project(Cuda-project)

set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/CMake/cuda" ${CMAKE_MODULE_PATH})

find_package(CUDA QUIET REQUIRED)

set(CUDA_ATTACH_VS_BUILD_RULE_TO_CUDA_FILE OFF)

set(BUILD_SHARED_LIBS ON)

list(APPEND CUDA_NVCC_FLAGS -DBLAH="he he" -DTEST1="this is a test")

CUDA_ADD_LIBRARY(test_lib
  kernel.cu
  lib.cu
  # SHARED
  # STATIC
  OPTIONS -DSTUFF="blah blah"
  RELEASE --use_fast_math -DNDEBUG
  DEBUG -g -DDEBUG
  )


INSTALL(FILES lib.h kernel.h
  DESTINATION include)
INSTALL(FILES "${CMAKE_BINARY_DIR}/libtest_lib.so" 
  DESTINATION lib)
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