src/gromacs/mdrunutility/threadaffinity.h

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  36 /*! \libinternal \file
  37  * \brief
  38  * Declares functions for managing mdrun thread affinity.
  39  *
  40  * \inlibraryapi
  41  * \ingroup module_mdrunutility
  42  */
  43 #ifndef GMX_MDRUNUTILITY_THREADAFFINITY_H
  44 #define GMX_MDRUNUTILITY_THREADAFFINITY_H
  45
  46 #include <cstdio>
  47
  48 #include "gromacs/utility/basedefinitions.h"
  49
  50 struct gmx_hw_opt_t;
  51 struct gmx_multisim_t;
  52 struct t_commrec;
  53
  54 namespace gmx
  55 {
  56
  57 class HardwareTopology;
  58 class MDLogger;
  59 class PhysicalNodeCommunicator;
  60
  61 class IThreadAffinityAccess
  62 {
  63 public:
  64     virtual bool isThreadAffinitySupported() const        = 0;
  65     virtual bool setCurrentThreadAffinityToCore(int core) = 0;
  66
  67 protected:
  68     virtual ~IThreadAffinityAccess();
  69 };
  70
  71 } // namespace gmx
  72
  73 /*! \brief Communicates within physical nodes to discover the
  74  * distribution of threads over ranks. */
  75 void analyzeThreadsOnThisNode(const gmx::PhysicalNodeCommunicator& physicalNodeComm,
  76                               int                                  numThreadsOnThisRank,
  77                               int*                                 numThreadsOnThisNode,
  78                               int*                                 intraNodeThreadOffset);
  79
  80 /*! \brief
  81  * Sets the thread affinity using the requested setting stored in hw_opt.
  82  *
  83  * See analyzeThreadsOnThisNode(), which prepares some of the input.
  84  *
  85  * \param[out] mdlog                  Logger.
  86  * \param[in]  cr                     Communication handler.
  87  * \param[in]  hw_opt                 Accesses user choices for thread affinity handling.
  88  * \param[in]  hwTop                  Detected hardware topology.
  89  * \param[in]  numThreadsOnThisRank   The number of threads on this rank.
  90  * \param[in]  numThreadsOnThisNode   The number of threads on all ranks of this node.
  91  * \param[in]  intraNodeThreadOffset  The index of the first hardware thread of this rank
  92  *   in the set of all the threads of all MPI ranks within a node (ordered by MPI rank ID).
  93  * \param[in]  affinityAccess         Interface for low-level access to affinity details.
  94  */
  95 void 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 gmx_check_thread_affinity_set(const gmx::MDLogger& mdlog,
 119                                    gmx_hw_opt_t*        hw_opt,
 120                                    int                  ncpus,
 121                                    gmx_bool             bAfterOpenmpInit);
 122
 123 #endif