Merged in feature/mkl-off-by-default-and-performance-docs (pull request #393)
Turn MKL off by default. Add section on performance to INSTALL.md Approved-by: Frank Dellaert <dellaert@cc.gatech.edu>release/4.3a0
Chris Beall
commit
e2bae62b01
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@ -61,8 +61,8 @@ option(GTSAM_POSE3_EXPMAP "Enable/Disable using Pose3::EXPMAP as the defau
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option(GTSAM_ROT3_EXPMAP "Ignore if GTSAM_USE_QUATERNIONS is OFF (Rot3::EXPMAP by default). Otherwise, enable Rot3::EXPMAP, or if disabled, use Rot3::CAYLEY." OFF)
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option(GTSAM_ENABLE_CONSISTENCY_CHECKS "Enable/Disable expensive consistency checks" OFF)
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option(GTSAM_WITH_TBB "Use Intel Threaded Building Blocks (TBB) if available" ON)
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option(GTSAM_WITH_EIGEN_MKL "Eigen will use Intel MKL if available" ON)
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option(GTSAM_WITH_EIGEN_MKL_OPENMP "Eigen, when using Intel MKL, will also use OpenMP for multithreading if available" ON)
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option(GTSAM_WITH_EIGEN_MKL "Eigen will use Intel MKL if available" OFF)
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option(GTSAM_WITH_EIGEN_MKL_OPENMP "Eigen, when using Intel MKL, will also use OpenMP for multithreading if available" OFF)
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option(GTSAM_THROW_CHEIRALITY_EXCEPTION "Throw exception when a triangulated point is behind a camera" ON)
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option(GTSAM_BUILD_PYTHON "Enable/Disable building & installation of Python module" OFF)
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option(GTSAM_ALLOW_DEPRECATED_SINCE_V4 "Allow use of methods/functions deprecated in GTSAM 4" ON)
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@ -564,10 +564,10 @@ if(GTSAM_WITH_TBB AND NOT TBB_FOUND)
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message(WARNING "TBB was not found - this is ok, but note that GTSAM parallelization will be disabled. Set GTSAM_WITH_TBB to 'Off' to avoid this warning.")
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endif()
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if(GTSAM_WITH_EIGEN_MKL AND NOT MKL_FOUND)
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message(WARNING "MKL was not found - this is ok, but note that MKL yields better performance. Set GTSAM_WITH_EIGEN_MKL to 'Off' to disable this warning.")
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message(WARNING "MKL was not found - this is ok, but note that MKL will be disabled. Set GTSAM_WITH_EIGEN_MKL to 'Off' to disable this warning. See INSTALL.md for notes on performance.")
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endif()
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if(GTSAM_WITH_EIGEN_MKL_OPENMP AND NOT OPENMP_FOUND AND MKL_FOUND)
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message(WARNING "Your compiler does not support OpenMP - this is ok, but performance may be improved with OpenMP. Set GTSAM_WITH_EIGEN_MKL_OPENMP to 'Off' to avoid this warning.")
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message(WARNING "Your compiler does not support OpenMP. Set GTSAM_WITH_EIGEN_MKL_OPENMP to 'Off' to avoid this warning. See INSTALL.md for notes on performance.")
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endif()
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if(GTSAM_BUILD_PYTHON AND GTSAM_PYTHON_WARNINGS)
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message(WARNING "${GTSAM_PYTHON_WARNINGS}")
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37
INSTALL.md
37
INSTALL.md
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@ -23,18 +23,22 @@ $ make install
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disable the CMake flag GTSAM_WITH_TBB (enabled by default). On Ubuntu, TBB
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may be installed from the Ubuntu repositories, and for other platforms it
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may be downloaded from https://www.threadingbuildingblocks.org/
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- GTSAM may be configured to use MKL by toggling `GTSAM_WITH_EIGEN_MKL` and
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`GTSAM_WITH_EIGEN_MKL_OPENMP` to `ON`; however, best performance is usually
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achieved with MKL disabled. We therefore advise you to benchmark your problem
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before using MKL.
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Tested compilers:
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- GCC 4.2-4.7
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- OSX Clang 2.9-5.0
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- OSX GCC 4.2
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- MSVC 2010, 2012
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- GCC 4.2-7.3
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- OS X Clang 2.9-10.0
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- OS X GCC 4.2
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- MSVC 2010, 2012, 2017
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Tested systems:
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- Ubuntu 11.04 - 18.04
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- MacOS 10.6 - 10.9
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- Ubuntu 16.04 - 18.04
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- MacOS 10.6 - 10.14
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- Windows 7, 8, 8.1, 10
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Known issues:
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@ -134,6 +138,27 @@ MEX_COMMAND: Path to the mex compiler. Defaults to assume the path is included i
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$MATLABROOT can be found by executing the command `matlabroot` in MATLAB
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## Performance
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Here are some tips to get the best possible performance out of GTSAM.
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1. Build in `Release` mode. GTSAM will run up to 10x faster compared to `Debug` mode.
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2. Enable TBB. On modern processors with multiple cores, this can easily speed up
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optimization by 30-50%. Please note that this may not be true for very small
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problems where the overhead of dispatching work to multiple threads outweighs
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the benefit. We recommend that you benchmark your problem with/without TBB.
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3. Add `-march=native` to `GTSAM_CMAKE_CXX_FLAGS`. A performance gain of
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25-30% can be expected on modern processors. Note that this affects the portability
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of your executable. It may not run when copied to another system with older/different
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processor architecture.
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Also note that all dependent projects *must* be compiled with the same flag, or
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seg-faults and other undefined behavior may result.
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4. Possibly enable MKL. Please note that our benchmarks have shown that this helps only
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in very limited cases, and actually hurts performance in the usual case. We therefore
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recommend that you do *not* enable MKL, unless you have benchmarked it on
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your problem and have verified that it improves performance.
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## Debugging tips
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Another useful debugging symbol is _GLIBCXX_DEBUG, which enables debug checks and safe containers in the standard C++ library and makes problems much easier to find.
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