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simple_memoryspaces.cpp
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Wed, Jul 24, 02:26

simple_memoryspaces.cpp
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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
*/
#include <Kokkos_Core.hpp>
#include <cstdio>
// The type of a two-dimensional N x 3 array of double.
// It lives in Kokkos' default memory space.
typedef Kokkos::View<double*[3]> view_type;
// The "HostMirror" type corresponding to view_type above is also a
// two-dimensional N x 3 array of double. However, it lives in the
// host memory space corresponding to view_type's memory space. For
// example, if view_type lives in CUDA device memory, host_view_type
// lives in host (CPU) memory. Furthermore, declaring host_view_type
// as the host mirror of view_type means that host_view_type has the
// same layout as view_type. This makes it easier to copy between the
// two Views.
// Advanced issues: If a memory space is accessible from the host without
// performance penalties then it is its own host_mirror_space. This is
// the case for HostSpace, CudaUVMSpace and CudaHostPinnedSpace.
typedef view_type::HostMirror host_view_type;
struct ReduceFunctor {
view_type a;
ReduceFunctor (view_type a_) : a (a_) {}
typedef int value_type; //Specify type for reduction value, lsum
KOKKOS_INLINE_FUNCTION
void operator() (int i, int &lsum) const {
lsum += a(i,0)-a(i,1)+a(i,2);
}
};
int main() {
Kokkos::initialize();
view_type a ("A", 10);
// If view_type and host_mirror_type live in the same memory space,
// a "mirror view" is just an alias, and deep_copy does nothing.
// Otherwise, a mirror view of a device View lives in host memory,
// and deep_copy does a deep copy.
host_view_type h_a = Kokkos::create_mirror_view (a);
// The View h_a lives in host (CPU) memory, so it's legal to fill
// the view sequentially using ordinary code, like this.
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 3; j++) {
h_a(i,j) = i*10 + j;
}
}
Kokkos::deep_copy (a, h_a); // Copy from host to device.
int sum = 0;
Kokkos::parallel_reduce (10, ReduceFunctor (a), sum);
printf ("Result is %i\n",sum);
Kokkos::finalize ();
}

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