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lammps/lib/kokkos/example/relocatable_function/main.cpp
2024-12-13 09:23:03 -07:00

51 lines
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C++

//@HEADER
// ************************************************************************
//
// Kokkos v. 4.0
// Copyright (2022) National Technology & Engineering
// Solutions of Sandia, LLC (NTESS).
//
// Under the terms of Contract DE-NA0003525 with NTESS,
// the U.S. Government retains certain rights in this software.
//
// Part of Kokkos, under the Apache License v2.0 with LLVM Exceptions.
// See https://kokkos.org/LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//@HEADER
#include <Kokkos_Core.hpp>
#include <iostream>
KOKKOS_RELOCATABLE_FUNCTION void count_even(const long i, long& lcount);
int main(int argc, char* argv[]) {
Kokkos::ScopeGuard scope_guard(argc, argv);
for (int n = 10; n <= 100'000'000; n *= 10) {
Kokkos::Timer timer;
long count = 0;
// Compute the number of even integers from 0 to n-1 using a relocatable
// functor
Kokkos::parallel_reduce(
n, KOKKOS_LAMBDA(const long i, long& lcount) { count_even(i, lcount); },
count);
double count_time_relocatable = timer.seconds();
timer.reset();
// Compute the number of even integers from 0 to n-1 using an inline lambda
Kokkos::parallel_reduce(
n,
KOKKOS_LAMBDA(const long i, long& lcount) { lcount += (i % 2) == 0; },
count);
double count_time_inline = timer.seconds();
std::cout << std::scientific << n * 1. << ' ' << count_time_relocatable
<< "s (relocatable) vs. " << count_time_inline << "s (inline)\n";
}
}