src/gromacs/mdrunutility/threadaffinity.h

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  35 /*! \libinternal \file
  36  * \brief
  37  * Declares functions for managing mdrun thread affinity.
  38  *
  39  * \inlibraryapi
  40  * \ingroup module_mdrunutility
  41  */
  42 #ifndef GMX_MDRUNUTILITY_THREADAFFINITY_H
  43 #define GMX_MDRUNUTILITY_THREADAFFINITY_H
  44
  45 #include <cstdio>
  46
  47 #include "gromacs/utility/basedefinitions.h"
  48
  49 struct gmx_hw_opt_t;
  50 struct gmx_multisim_t;
  51 struct t_commrec;
  52
  53 namespace gmx
  54 {
  55
  56 class HardwareTopology;
  57 class MDLogger;
  58 class PhysicalNodeCommunicator;
  59
  60 class IThreadAffinityAccess
  61 {
  62     public:
  63         virtual bool isThreadAffinitySupported() const        = 0;
  64         virtual bool setCurrentThreadAffinityToCore(int core) = 0;
  65
  66     protected:
  67         virtual ~IThreadAffinityAccess();
  68 };
  69
  70 } // namespace gmx
  71
  72 /*! \brief Communicates within physical nodes to discover the
  73  * distribution of threads over ranks. */
  74 void analyzeThreadsOnThisNode(const gmx::PhysicalNodeCommunicator &physicalNodeComm,
  75                               int                                  numThreadsOnThisRank,
  76                               int                                 *numThreadsOnThisNode,
  77                               int                                 *intraNodeThreadOffset);
  78
  79 /*! \brief
  80  * Sets the thread affinity using the requested setting stored in hw_opt.
  81  *
  82  * See analyzeThreadsOnThisNode(), which prepares some of the input.
  83  *
  84  * \param[out] mdlog                  Logger.
  85  * \param[in]  cr                     Communication handler.
  86  * \param[in]  hw_opt                 Accesses user choices for thread affinity handling.
  87  * \param[in]  hwTop                  Detected hardware topology.
  88  * \param[in]  numThreadsOnThisRank   The number of threads on this rank.
  89  * \param[in]  numThreadsOnThisNode   The number of threads on all ranks of this node.
  90  * \param[in]  intraNodeThreadOffset  The index of the first hardware thread of this rank
  91  *   in the set of all the threads of all MPI ranks within a node (ordered by MPI rank ID).
  92  * \param[in]  affinityAccess         Interface for low-level access to affinity details.
  93  */
  94 void
  95 gmx_set_thread_affinity(const gmx::MDLogger         &mdlog,
  96                         const t_commrec             *cr,
  97                         const gmx_hw_opt_t          *hw_opt,
  98                         const gmx::HardwareTopology &hwTop,
  99                         int                          numThreadsOnThisRank,
 100                         int                          numThreadsOnThisNode,
 101                         int                          intraNodeThreadOffset,
 102                         gmx::IThreadAffinityAccess  *affinityAccess);
 103
 104 /*! \brief
 105  * Checks the process affinity mask and if it is found to be non-zero,
 106  * will honor it and disable mdrun internal affinity setting.
 107  *
 108  * This function should be called first before the OpenMP library gets
 109  * initialized with the last argument FALSE (which will detect affinity
 110  * set by external tools like taskset), and later, after the OpenMP
 111  * initialization, with the last argument TRUE to detect affinity changes
 112  * made by the OpenMP library.
 113  *
 114  * Note that this will only work on Linux as we use a GNU feature.
 115  * With bAfterOpenmpInit false, it will also detect whether OpenMP environment
 116  * variables for setting the affinity are set.
 117  */
 118 void
 119 gmx_check_thread_affinity_set(const gmx::MDLogger &mdlog,
 120                               gmx_hw_opt_t *hw_opt, int ncpus,
 121                               gmx_bool bAfterOpenmpInit);
 122
 123 #endif