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Kokkos_Rendezvous.hpp
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Tue, May 21, 06:05

Kokkos_Rendezvous.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_IMPL_RENDEZVOUS_HPP
#define KOKKOS_IMPL_RENDEZVOUS_HPP
#include <cstdint>
namespace Kokkos { namespace Impl {
inline
constexpr int rendezvous_buffer_size( int max_members ) noexcept
{
return (((max_members + 7) / 8) * 4) + 4 + 4;
}
/** \brief Thread pool rendezvous
*
* Rendezvous pattern:
* if ( rendezvous(root) ) {
* ... only root thread here while all others wait ...
* rendezvous_release();
* }
* else {
* ... all other threads release here ...
* }
*
* Requires: buffer[ rendezvous_buffer_size( max_threads ) ];
*
* When slow != 0 the expectation is thread arrival will be
* slow so the threads that arrive early should quickly yield
* their core to the runtime thus possibly allowing the late
* arriving threads to have more resources
* (e.g., power and clock frequency).
*/
int rendezvous( volatile int64_t * const buffer
, int const size
, int const rank
, int const slow = 0 ) noexcept ;
void rendezvous_release( volatile int64_t * const buffer ) noexcept ;
}} // namespace Kokkos::Impl
#endif // KOKKOS_IMPL_RENDEZVOUS_HPP

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