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FindMPI: Use physical cores for MPIEXEC_MAX_NUMPROCS

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Since commit v3.9.0-rc1~224^2~1 (FindMPI: MPIEXEC handling improvements,
2017-04-21) the `ProcessorCount` module is being used to initialize
`MPIEXEC_MAX_NUMPROCS`.  However, this leads to the logical cores being
counted rather than the physical ones, and some MPI implementations like
OpenMPI will error if mpiexec is called with that number.  Switch it to
the number of physical cores using `cmake_host_system_information`.

This ensures that if `MPIEXEC_MAX_NUMPROCS` is being used to set up MPI
tests with CTest or similar that the tests won't spuriously fail due to
OpenMPI refusing to start the application.
This commit is contained in:
Christian Pfeiffer
2017-10-24 16:14:14 +02:00
committed by Brad King
parent a91eb5e41f
commit 1610f757ac
1 changed files with 2 additions and 7 deletions
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9
Modules/FindMPI.cmake
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@@ -1036,13 +1036,8 @@ set(MPIEXEC_NUMPROC_FLAG "-n" CACHE STRING "Flag used by MPI to specify the num
set(MPIEXEC_PREFLAGS "" CACHE STRING "These flags will be directly before the executable that is being run by mpiexec.")
set(MPIEXEC_POSTFLAGS "" CACHE STRING "These flags will be placed after all flags passed to mpiexec.")
# Set the number of processes to the processor count and the previous default
# of 2 if that couldn't be determined.
include(${CMAKE_CURRENT_LIST_DIR}/ProcessorCount.cmake)
ProcessorCount(_MPIEXEC_NUMPROCS)
if("${_MPIEXEC_NUMPROCS}" EQUAL "0")
set(_MPIEXEC_NUMPROCS 2)
endif()
# Set the number of processes to the physical processor count
cmake_host_system_information(RESULT _MPIEXEC_NUMPROCS QUERY NUMBER_OF_PHYSICAL_CORES)
set(MPIEXEC_MAX_NUMPROCS "${_MPIEXEC_NUMPROCS}" CACHE STRING "Maximum number of processors available to run MPI applications.")
unset(_MPIEXEC_NUMPROCS)
mark_as_advanced(MPIEXEC_EXECUTABLE MPIEXEC_NUMPROC_FLAG MPIEXEC_PREFLAGS MPIEXEC_POSTFLAGS MPIEXEC_MAX_NUMPROCS)