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Kokkos_hwloc.hpp
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Kokkos_hwloc.hpp
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/*
//@HEADER
// ************************************************************************
//
// Kokkos v. 2.0
// Copyright (2014) Sandia Corporation
//
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// 3. Neither the name of the Corporation nor the names of the
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Questions? Contact H. Carter Edwards (hcedwar@sandia.gov)
//
// ************************************************************************
//@HEADER
*/
#ifndef KOKKOS_HWLOC_HPP
#define KOKKOS_HWLOC_HPP
#include <utility>
namespace Kokkos {
/** \brief Minimal subset of logical 'hwloc' functionality available
* from http://www.open-mpi.org/projects/hwloc/.
*
* The calls are NOT thread safe in order to avoid mutexes,
* memory allocations, or other actions which could give the
* runtime system an opportunity to migrate the threads or
* touch allocated memory during the function calls.
*
* All calls to these functions should be performed by a thread
* when it has guaranteed exclusive access; e.g., for OpenMP
* within a 'critical' region.
*/
namespace hwloc {
/** \brief Query if hwloc is available */
bool available();
/** \brief Query number of available NUMA regions.
* This will be less than the hardware capacity
* if the MPI process is pinned to a NUMA region.
*/
unsigned get_available_numa_count();
/** \brief Query number of available cores per NUMA regions.
* This will be less than the hardware capacity
* if the MPI process is pinned to a set of cores.
*/
unsigned get_available_cores_per_numa();
/** \brief Query number of available "hard" threads per core; i.e., hyperthreads */
unsigned get_available_threads_per_core();
} /* namespace hwloc */
} /* namespace Kokkos */
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// Internal functions for binding persistent spawned threads.
namespace Kokkos {
namespace hwloc {
/** \brief Recommend mapping of threads onto cores.
*
* If thread_count == 0 then choose and set a value.
* If use_numa_count == 0 then choose and set a value.
* If use_cores_per_numa == 0 then choose and set a value.
*
* Return 0 if asynchronous,
* Return 1 if synchronous and threads_coord[0] is process core
*/
unsigned thread_mapping( const char * const label ,
const bool allow_async ,
unsigned & thread_count ,
unsigned & use_numa_count ,
unsigned & use_cores_per_numa ,
std::pair<unsigned,unsigned> threads_coord[] );
/** \brief Query core-coordinate of the current thread
* with respect to the core_topology.
*
* As long as the thread is running within the
* process binding the following condition holds.
*
* core_coordinate.first < core_topology.first
* core_coordinate.second < core_topology.second
*/
std::pair<unsigned,unsigned> get_this_thread_coordinate();
/** \brief Bind the current thread to a core. */
bool bind_this_thread( const std::pair<unsigned,unsigned> );
/** \brief Can hwloc bind threads? */
bool can_bind_threads();
/** \brief Bind the current thread to one of the cores in the list.
* Set that entry to (~0,~0) and return the index.
* If binding fails return ~0.
*/
unsigned bind_this_thread( const unsigned coordinate_count ,
std::pair<unsigned,unsigned> coordinate[] );
/** \brief Unbind the current thread back to the original process binding */
bool unbind_this_thread();
} /* namespace hwloc */
} /* namespace Kokkos */
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
#endif /* #define KOKKOS_HWLOC_HPP */

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