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 /*
  * SPDX-License-Identifier: BSD-3-Clause
  * Copyright © 2020-2021 Inria.  All rights reserved.
  * See COPYING in top-level directory.
  */
 
 /** \file
  * \brief Kinds of CPU cores.
  */
 
 #ifndef HWLOC_CPUKINDS_H
 #define HWLOC_CPUKINDS_H
 
 #include "hwloc.h"
 
 #ifdef __cplusplus
 extern "C" {
 #elif 0
 }
 #endif
 
 /** \defgroup hwlocality_cpukinds Kinds of CPU cores
  *
  * Platforms with heterogeneous CPUs may have some cores with
  * different features or frequencies.
  * This API exposes identical PUs in sets called CPU kinds.
  * Each PU of the topology may only be in a single kind.
  *
  * The number of kinds may be obtained with hwloc_cpukinds_get_nr().
  * If the platform is homogeneous, there may be a single kind
  * with all PUs.
  * If the platform or operating system does not expose any
  * information about CPU cores, there may be no kind at all.
  *
  * The index of the kind that describes a given CPU set
  * (if any, and not partially)
  * may be obtained with hwloc_cpukinds_get_by_cpuset().
  *
  * From the index of a kind, it is possible to retrieve information
  * with hwloc_cpukinds_get_info():
  * an abstracted efficiency value,
  * and an array of info attributes
  * (for instance the "CoreType" and "FrequencyMaxMHz",
  *  see \ref topoattrs_cpukinds).
  *
  * A higher efficiency value means greater intrinsic performance
  * (and possibly less performance/power efficiency).
  * Kinds with lower efficiency values are ranked first:
  * Passing 0 as \p kind_index to hwloc_cpukinds_get_info() will
  * return information about the CPU kind with lower performance
  * but higher energy-efficiency.
  * Higher \p kind_index values would rather return information
  * about power-hungry high-performance cores.
  *
  * When available, efficiency values are gathered from the operating system.
  * If so, \p cpukind_efficiency is set in the struct hwloc_topology_discovery_support array.
  * This is currently available on Windows 10, Mac OS X (Darwin),
  * and on some Linux platforms where core "capacity" is exposed in sysfs.
  *
  * If the operating system does not expose core efficiencies natively,
  * hwloc tries to compute efficiencies by comparing CPU kinds using
  * frequencies (on ARM), or core types and frequencies (on other architectures).
  * The environment variable HWLOC_CPUKINDS_RANKING may be used
  * to change this heuristics, see \ref envvar_heuristics.
  *
  * If hwloc fails to rank any kind, for instance because the operating
  * system does not expose efficiencies and core frequencies,
  * all kinds will have an unknown efficiency (\c -1),
  * and they are not indexed/ordered in any specific way.
  *
  * @{
  */
 
 /** \brief Get the number of different kinds of CPU cores in the topology.
  *
  * \p flags must be \c 0 for now.
  *
  * \return The number of CPU kinds (positive integer) on success.
  * \return \c 0 if no information about kinds was found.
  * \return \c -1 with \p errno set to \c EINVAL if \p flags is invalid.
  */
 HWLOC_DECLSPEC int
 hwloc_cpukinds_get_nr(hwloc_topology_t topology,
                       unsigned long flags);
 
 /** \brief Get the index of the CPU kind that contains CPUs listed in \p cpuset.
  *
  * \p flags must be \c 0 for now.
  *
  * \return The index of the CPU kind (positive integer or 0) on success.
  * \return \c -1 with \p errno set to \c EXDEV if \p cpuset is
  * only partially included in the some kind.
  * \return \c -1 with \p errno set to \c ENOENT if \p cpuset is
  * not included in any kind, even partially.
  * \return \c -1 with \p errno set to \c EINVAL if parameters are invalid.
  */
 HWLOC_DECLSPEC int
 hwloc_cpukinds_get_by_cpuset(hwloc_topology_t topology,
                              hwloc_const_bitmap_t cpuset,
                              unsigned long flags);
 
 /** \brief Get the CPU set and infos about a CPU kind in the topology.
  *
  * \p kind_index identifies one kind of CPU between 0 and the number
  * of kinds returned by hwloc_cpukinds_get_nr() minus 1.
  *
  * If not \c NULL, the bitmap \p cpuset will be filled with
  * the set of PUs of this kind.
  *
  * The integer pointed by \p efficiency, if not \c NULL will, be filled
  * with the ranking of this kind of CPU in term of efficiency (see above).
  * It ranges from \c 0 to the number of kinds
  * (as reported by hwloc_cpukinds_get_nr()) minus 1.
  *
  * Kinds with lower efficiency are reported first.
  *
  * If there is a single kind in the topology, its efficiency \c 0.
  * If the efficiency of some kinds of cores is unknown,
  * the efficiency of all kinds is set to \c -1,
  * and kinds are reported in no specific order.
  *
  * The array of info attributes (for instance the "CoreType",
  * "FrequencyMaxMHz" or "FrequencyBaseMHz", see \ref topoattrs_cpukinds)
  * and its length are returned in \p infos or \p nr_infos.
  * The array belongs to the topology, it should not be freed or modified.
  *
  * If \p nr_infos or \p infos is \c NULL, no info is returned.
  *
  * \p flags must be \c 0 for now.
  *
  * \return \c 0 on success.
  * \return \c -1 with \p errno set to \c ENOENT if \p kind_index does not match any CPU kind.
  * \return \c -1 with \p errno set to \c EINVAL if parameters are invalid.
  */
 HWLOC_DECLSPEC int
 hwloc_cpukinds_get_info(hwloc_topology_t topology,
                         unsigned kind_index,
                         hwloc_bitmap_t cpuset,
                         int *efficiency,
                         unsigned *nr_infos, struct hwloc_info_s **infos,
                         unsigned long flags);
 
 /** \brief Register a kind of CPU in the topology.
  *
  * Mark the PUs listed in \p cpuset as being of the same kind
  * with respect to the given attributes.
  *
  * \p forced_efficiency should be \c -1 if unknown.
  * Otherwise it is an abstracted efficiency value to enforce
  * the ranking of all kinds if all of them have valid (and
  * different) efficiencies.
  *
  * The array \p infos of size \p nr_infos may be used to provide
  * info names and values describing this kind of PUs.
  *
  * \p flags must be \c 0 for now.
  *
  * Parameters \p cpuset and \p infos will be duplicated internally,
  * the caller is responsible for freeing them.
  *
  * If \p cpuset overlaps with some existing kinds, those might get
  * modified or split. For instance if existing kind A contains
  * PUs 0 and 1, and one registers another kind for PU 1 and 2,
  * there will be 3 resulting kinds:
  * existing kind A is restricted to only PU 0;
  * new kind B contains only PU 1 and combines information from A
  * and from the newly-registered kind;
  * new kind C contains only PU 2 and only gets information from
  * the newly-registered kind.
  *
  * \note The efficiency \p forced_efficiency provided to this function
  * may be different from the one reported later by hwloc_cpukinds_get_info()
  * because hwloc will scale efficiency values down to
  * between 0 and the number of kinds minus 1.
  *
  * \return \c 0 on success.
  * \return \c -1 with \p errno set to \c EINVAL if some parameters are invalid,
  * for instance if \p cpuset is \c NULL or empty.
  */
 HWLOC_DECLSPEC int
 hwloc_cpukinds_register(hwloc_topology_t topology,
                         hwloc_bitmap_t cpuset,
                         int forced_efficiency,
                         unsigned nr_infos, struct hwloc_info_s *infos,
                         unsigned long flags);
 
 /** @} */
 
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
 
 
 #endif /* HWLOC_CPUKINDS_H */

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