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project_6/cccl_upstream/cub/benchmarks/bench/reduce/nondeterministic.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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// SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: BSD-3-Clause
#include <cub/device/device_reduce.cuh>
#include <cuda/execution.determinism.h>
#include <cuda/execution.require.h>
#include <nvbench_helper.cuh>
#include <nvbench/range.cuh>
#include <nvbench/types.cuh>
// %RANGE% TUNE_ITEMS_PER_THREAD ipt 3:24:1
// %RANGE% TUNE_THREADS_PER_BLOCK tpb 128:1024:32
// %RANGE% TUNE_ITEMS_PER_VEC_LOAD_POW2 ipv 1:2:1
#if !TUNE_BASE
template <typename AccumT>
struct policy_selector
{
[[nodiscard]] _CCCL_HOST_DEVICE constexpr auto operator()(cuda::compute_capability) const -> cub::ReducePolicy
{
const auto [items, threads] =
cub::detail::scale_mem_bound(TUNE_THREADS_PER_BLOCK, TUNE_ITEMS_PER_THREAD, int{sizeof(AccumT)});
const auto policy = cub::ReducePassPolicy{
threads,
items,
1 << TUNE_ITEMS_PER_VEC_LOAD_POW2,
cub::BLOCK_REDUCE_WARP_REDUCTIONS_NONDETERMINISTIC,
cub::LOAD_DEFAULT};
return {policy, {}};
}
};
#endif // !TUNE_BASE
template <typename T, typename OffsetT>
void nondeterministic_sum(nvbench::state& state, nvbench::type_list<T, OffsetT>)
{
using op_t = cuda::std::plus<>;
using init_value_t = T;
// Retrieve axis parameters
const auto elements = static_cast<std::size_t>(state.get_int64("Elements{io}"));
thrust::device_vector<T> in = generate(elements);
thrust::device_vector<T> out(1);
auto d_in = thrust::raw_pointer_cast(in.data());
auto d_out = thrust::raw_pointer_cast(out.data());
// Enable throughput calculations and add "Size" column to results.
state.add_element_count(elements);
state.add_global_memory_reads<T>(elements, "Size");
state.add_global_memory_writes<T>(1);
caching_allocator_t alloc;
state.exec(nvbench::exec_tag::gpu | nvbench::exec_tag::no_batch, [&](nvbench::launch& launch) {
auto env = cub_bench_env(
alloc,
launch,
cuda::execution::require(cuda::execution::determinism::not_guaranteed)
#if !TUNE_BASE
,
cuda::execution::tune(policy_selector<cuda::std::__accumulator_t<op_t, T, init_value_t>>{})
#endif // !TUNE_BASE
);
_CCCL_TRY_CUDA_API(
cub::DeviceReduce::Reduce,
"Reduce failed",
d_in,
d_out,
static_cast<OffsetT>(elements),
op_t{},
init_value_t{},
env);
});
}
#ifdef TUNE_T
using value_types = nvbench::type_list<TUNE_T>;
#else
using value_types = nvbench::type_list<int32_t, int64_t, float, double>;
#endif
NVBENCH_BENCH_TYPES(nondeterministic_sum, NVBENCH_TYPE_AXES(value_types, offset_types))
.set_name("base")
.set_type_axes_names({"T{ct}", "OffsetT{ct}"})
.add_int64_power_of_two_axis("Elements{io}", nvbench::range(16, 28, 4));