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/*
* Copyright (c) 2020 Arm Limited.
*
* SPDX-License-Identifier: MIT
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "src/runtime/SchedulerUtils.h"
#include "arm_compute/core/Error.h"
#include <cmath>
namespace arm_compute
{
namespace scheduler_utils
{
#ifndef BARE_METAL
std::pair<unsigned, unsigned> split_2d(unsigned max_threads, std::size_t m, std::size_t n)
{
/*
* We want the same ratio of threads in M & N to the ratio of m and n problem size
*
* Therefore: mt/nt == m/n where mt*nt == max_threads
*
* max_threads/nt = mt & (max_threads/nt) * (m/n) = nt
* nt^2 = max_threads * (m/n)
* nt = sqrt( max_threads * (m/n) )
*/
//ratio of m to n in problem dimensions
double ratio = m / static_cast<double>(n);
// nt = sqrt(max_threads * (m / n) )
const unsigned adjusted = std::round(std::sqrt(max_threads * ratio));
//find the nearest factor of max_threads
for (unsigned i = 0; i != adjusted; ++i)
{
//try down
const unsigned adj_down = adjusted - i;
if (max_threads % adj_down == 0)
{
return {adj_down, max_threads / adj_down};
}
//try up
const unsigned adj_up = adjusted + i;
if (max_threads % adj_up == 0)
{
return {adj_up, max_threads / adj_up};
}
}
//we didn't find anything so lets bail out with maxes biased to the largest dimension
if (m > n)
{
return {std::min<unsigned>(m, max_threads), 1};
}
else
{
return {1, std::min<unsigned>(n, max_threads)};
}
}
#endif /* #ifndef BARE_METAL */
} // namespace scheduler_utils
} // namespace arm_compute
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