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Kokkos_ClockTic.hpp
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Fri, Aug 16, 20:01

Kokkos_ClockTic.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_CLOCKTIC_HPP
#define KOKKOS_CLOCKTIC_HPP
#include <Kokkos_Macros.hpp>
#include <stdint.h>
#include <chrono>
namespace Kokkos {
namespace Impl {
/**\brief Quick query of clock register tics
*
* Primary use case is to, with low overhead,
* obtain a integral value that consistently varies
* across concurrent threads of execution within
* a parallel algorithm.
* This value is often used to "randomly" seed an
* attempt to acquire an indexed resource (e.g., bit)
* from an array of resources (e.g., bitset) such that
* concurrent threads will have high likelihood of
* having different index-seed values.
*/
KOKKOS_FORCEINLINE_FUNCTION
uint64_t clock_tic(void) noexcept
{
#if defined( __CUDA_ARCH__ )
// Return value of 64-bit hi-res clock register.
return clock64();
#elif defined( __i386__ ) || defined( __x86_64 )
// Return value of 64-bit hi-res clock register.
unsigned a = 0, d = 0;
__asm__ volatile( "rdtsc" : "=a" (a), "=d" (d) );
return ( (uint64_t) a ) | ( ( (uint64_t) d ) << 32 );
#elif defined( __powerpc ) || defined( __powerpc__ ) || \
defined( __powerpc64__ ) || defined( __POWERPC__ ) || \
defined( __ppc__ ) || defined( __ppc64__ )
unsigned int cycles = 0;
asm volatile( "mftb %0" : "=r" (cycles) );
return (uint64_t) cycles;
#else
return (uint64_t)
std::chrono::high_resolution_clock::now().time_since_epoch().count();
#endif
}
} // namespace Impl
} // namespace Kokkos
#endif // KOKKOS_CLOCKTIC_HPP

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