opm-simulators/opm/models/utils/prefetch.hh
2019-09-19 10:14:17 +02:00

55 lines
1.9 KiB
C++

// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
/*
This file is part of the Open Porous Media project (OPM).
OPM is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
OPM is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with OPM. If not, see <http://www.gnu.org/licenses/>.
Consult the COPYING file in the top-level source directory of this
module for the precise wording of the license and the list of
copyright holders.
*/
/*!
* \file
* \copydoc prefetch
*/
#ifndef EWOMS_PREFETCH_HH
#define EWOMS_PREFETCH_HH
namespace Opm {
/*!
* \brief Template function which emits prefetch instructions for a range of memory
*
* This function does not change the semantics of the code, but used correctly it will
* improve performace because the number of cache misses will be reduced.
*/
template <int temporalLocality = 3, int writeOnly = 0, class T = void>
void prefetch(const T& val, unsigned n = 1)
{
#if __clang__ || __GNUC__
// this value is architecture specific, but a cache line size of 64 bytes seems to be
// used by all contemporary architectures.
static const int cacheLineSize = 64;
const char *beginPtr = reinterpret_cast<const char*>(&val);
const char *endPtr = reinterpret_cast<const char*>(&val + n);
for (; beginPtr < endPtr; beginPtr += cacheLineSize)
__builtin_prefetch(beginPtr, writeOnly, temporalLocality);
#endif
}
} // namespace Opm
#endif