从CMake设置'make'默认使用'-j'选项 [英] From CMake setup 'make' to use '-j' option by default

问题描述

每当我从终端调用 make 时，我都希望我的CMake项目由 make -j N 构建。我不想每次都手动设置 -j 选项。

I want my CMake project to be built by make -j N, whenever I call make from the terminal. I don't want to set -j option manually every time.

为此，我设置了特定命令行的CMAKE_MAKE_PROGRAM 变量。我使用 ProcessorCount（）函数，该函数给出并行执行构建的处理器数量。

For that, I set CMAKE_MAKE_PROGRAM variable to the specific command line. I use the ProcessorCount() function, which gives the number of procesors to perform build in parallel.

当我做 make ，我看不到有任何提高。但是，如果我使用 make -j N ，那么它的构建速度肯定会更快。

When I do make, I do not see any speed up. However if I do make -j N, then it is built definitely faster.

请您帮我这个问题？ （我正在Linux上进行开发。）

Would you please help me on this issue? (I am developing this on Linux.)

这是我在 CMakeList.txt ：

include(ProcessorCount)
ProcessorCount(N)
message("number of processors: "  ${N})
if(NOT N EQUAL 0)
  set(CTEST_BUILD_FLAGS -j${N})
  set(ctest_test_args ${ctest_test_args} PARALLEL_LEVEL ${N})
  set(CMAKE_MAKE_PROGRAM "${CMAKE_MAKE_PROGRAM} -j ${N}")      
endif()
message("cmake make program" ${CMAKE_MAKE_PROGRAM})

非常感谢。

推荐答案

通过设置要影响构建过程的 CMAKE_MAKE_PROGRAM 变量。但是：

Via setting the CMAKE_MAKE_PROGRAM variable you want to affect the build process. But:

1. 该变量仅通过 cmake --build ，而不是在本地工具（ make ）调用中：

1. This variable affects only the build via cmake --build, not on native tool (make) call:

CMAKE_MAKE_PROGRAM 变量设置为由项目代码使用。该值也由cmake（1）-build 和ctest（1）-build-and-test 启动本机构建过程的工具。

The CMAKE_MAKE_PROGRAM variable is set for use by project code. The value is also used by the cmake(1) --build and ctest(1) --build-and-test tools to launch the native build process.

此变量应为 CACHE d一。类似 make 的生成器以这种方式使用它：

This variable should be a CACHEd one. It is used in such way by make-like generators:

这些生成器将CMAKE_MAKE_PROGRAM存储在CMake缓存中，因此

These generators store CMAKE_MAKE_PROGRAM in the CMake cache so that it may be edited by the user.

也就是说，您需要使用

set(CMAKE_MAKE_PROGRAM <program> CACHE PATH "Path to build tool" FORCE)

此变量应引用可执行文件本身，而不是带有参数的程序：

This variable should refer to the executable itself, not to a program with arguments:

该值可以是可执行文件的完整路径，也可以是工具名称（如果期望它位于PATH中）。

The value may be the full path to an executable or just the tool name if it is expected to be in the PATH.

也就是说，值 make -j 2不能用于该变量（将参数拆分为列表

That is, value "make -j 2" cannot be used for that variable (splitting arguments as list

set(CMAKE_MAKE_PROGRAM make -j 2 CACHE PATH "Path to build tool" FORCE)

总而言之，您可能会通过将 CMAKE_MAKE_PROGRAM 变量设置为 script （调用<$ c），重新定义 cmake --build 调用的行为$ c> make 和并行选项。但是您可能不会影响直接拨打的行为。

In summary, you may redefine the behavior of cmake --build calls with setting the CMAKE_MAKE_PROGRAM variable to the script, which calls make with parallel options. But you may not affect the behavior of direct make calls.

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