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project_6/cccl_upstream/cudax/examples/stf/launch_sum.cu
EngineX CI 56fd68e7dd [INFRA] Import NVIDIA/CCCL upstream as optimization reference library
CCCL (CUDA C++ Core Libraries) provides:
- CUB: device/block/warp-level GPU primitives (reduce, scan, sort, topk)
- Thrust: high-level parallel algorithms (transform_reduce, sort, scan)
- libcudacxx: CUDA C++ standard library (atomics, barriers, memory)
- cudax: experimental features (memory resources, allocators)
- Tuning policies: per-SM hardware-specific algorithm parameters

Competition optimization vectors mapped to CCCL:
- Output TPS (83% weight): warp_reduce, block_reduce, device_topk
- Input TPS (14% weight): device_scan, block_load, prefetch
- Cache TPS (3% weight): prefix caching strategy patterns
- Memory (0.9 util): pooled/cached/buddy allocators

Source: https://github.com/NVIDIA/cccl (shallow clone, HEAD only)
License: Apache-2.0
2026-07-30 09:35:51 +00:00

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//===----------------------------------------------------------------------===//
//
// Part of CUDASTF in CUDA C++ Core Libraries,
// under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// SPDX-FileCopyrightText: Copyright (c) 2022-2024 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//
/**
* @file
* @brief A reduction kernel written using launch
*/
#include <cuda/experimental/stf.cuh>
using namespace cuda::experimental::stf;
double X0(int i)
{
return sin((double) i);
}
int main()
{
context ctx;
const size_t N = 128 * 1024 * 1024;
std::vector<double> X(N);
double sum = 0.0;
double ref_sum = 0.0;
for (size_t ind = 0; ind < N; ind++)
{
X[ind] = sin((double) ind);
ref_sum += X[ind];
}
auto lX = ctx.logical_data(&X[0], {N});
auto lsum = ctx.logical_data(&sum, {1});
auto number_devices = 1; //
auto where = exec_place::repeat(exec_place::device(0), number_devices);
auto spec = par<16>(con<32>());
ctx.launch(spec, where, lX.read(), lsum.rw())->*[] _CCCL_DEVICE(auto th, auto x, auto sum) {
// Each thread computes the sum of elements assigned to it
double local_sum = 0.0;
for (size_t i = th.rank(); i < x.size(); i += th.size())
{
local_sum += x(i);
}
auto ti = th.inner();
__shared__ double block_sum[th.static_width(1)];
block_sum[ti.rank()] = local_sum;
for (size_t s = ti.size() / 2; s > 0; s /= 2)
{
ti.sync();
if (ti.rank() < s)
{
block_sum[ti.rank()] += block_sum[ti.rank() + s];
}
}
if (ti.rank() == 0)
{
atomicAdd(&sum(0), block_sum[0]);
}
};
ctx.finalize();
EXPECT(fabs(sum - ref_sum) < 0.0001);
}