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POParallel jobs using a CMake generated makefile (no speed improvement)
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12807806
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12830523
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1
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10
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2012-10-09T20:19:40.573
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2012-10-11T00:37:18.567
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2012-10-10T21:39:28.850
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5
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I have been doing some testing on a project that I recently started building with CMake. Before moving to CMake I noticed significant improvements in build time when using the <code>-j</code> option for <code>make</code> with my handwritten Makefile. Now with CMake I do the same thing and there isn't any noticeable increase in speed. Whether I run with <code>-j</code> or not, I get four processes for <code>make.exe</code>, though only one of them is clocking CPU time and never uses more the 25% of the CPU. In general, The CMake generated Makefile is much slower than my handwritten Makefile. A quick test shows build times for both CMake and handwritten makefiles with and without the <code>-j</code> flag: <pre><code>CMake: "make -j all" = 7min CMake: "make all" = 7min Handwritten: "make -j all" = 2min Handwritten: "make all" = 4min </code></pre> In general, CMake is much slower and doesn't seem to utilize parallel jobs. Can anyone explain why I'm not seeing any improvements? (Building a Fortran program with gfortran and using CMake's auto-detect dependency feature...though I don't know if that's relevant to what I'm seeing). Here's my CMakeLists.txt file: <pre><code>## CMake Version cmake_minimum_required(VERSION 2.8) ## Project Name project(PROJECT) ## Use FORTRAN enable_language(Fortran) ## Release compiler options set (CMAKE_Fortran_FLAGS_RELEASE "-O3 -cpp -ffree-line-length-none -fimplicit-none") ## Debug compiler options set (CMAKE_Fortran_FLAGS_DEBUG "-g -cpp -ffree-line-length-none -fimplicit-none") ## Set directory for FORTRAN modules set (CMAKE_Fortran_MODULE_DIRECTORY "${PROJECT_BINARY_DIR}/modules") ## Build Executable add_executable(EXE Source1.f90 Source2.f90 . . . Source219.f90 Source220.f90) </code></pre> And here's my original Makefile: <pre><code>PROG = PROGRAM.exe SRCS = Source1.f90 Source2.f90 ... Source219.o Source220.o OBJS = Source1.o Source2.o ... Source219.o Source220.o LIBS = VPATH = src BUILDDIR = debug F90 = gfortran F90FLAGS = -g -cpp -ffree-line-length-none -fimplicit-none all: $(PROG) $(PROG): $(OBJS) $(F90) -o $@ $(OBJS) $(LIBS) clean: erase -f $(BUILDDIR)$(PROG) $(BUILDDIR)\$(OBJS) $(BUILDDIR)\*.mod .SUFFIXES: $(SUFFIXES) .f90 .f90.o: $(F90) $(F90FLAGS) -c $< Source1.o: Dependency1.o Dependency2.o ... DependencyN.o Source2.o: Dependency1.o Dependency2.o ... DependencyN.o . . . Source219.o: Dependency1.o Dependency2.o ... DependencyN.o Source220.o: Dependency1.o Dependency2.o ... DependencyN.o </code></pre>
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<makefile><cmake><fortran>
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Parallel jobs using a CMake generated makefile (no speed improvement)
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