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warpAggregatedAtomicsCG.cu
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warpAggregatedAtomicsCG.cu
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/* Copyright (c) 2019, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of NVIDIA CORPORATION nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``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 THE COPYRIGHT OWNER OR
* 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.
*/
#include <stdio.h>
// includes, project
#include <helper_cuda.h>
#include <helper_functions.h>
#include <cuda_runtime.h>
#include <cooperative_groups.h>
namespace cg = cooperative_groups;
#define NUM_ELEMS 10000000
#define NUM_THREADS_PER_BLOCK 512
// warp-aggregated atomic increment
__device__ int atomicAggInc(int *counter) {
cg::coalesced_group active = cg::coalesced_threads();
int mask = active.ballot(1);
// select the leader
int leader = __ffs(mask) - 1;
// leader does the update
int res = 0;
if (active.thread_rank() == leader) {
res = atomicAdd(counter, __popc(mask));
}
// broadcast result
res = active.shfl(res, leader);
// each thread computes its own value
return res + __popc(mask & ((1 << active.thread_rank()) - 1));
}
__global__ void filter_arr(int *dst, int *nres, const int *src, int n) {
int id = threadIdx.x + blockIdx.x * blockDim.x;
for (int i = id; i < n; i += gridDim.x * blockDim.x) {
if (src[i] > 0) dst[atomicAggInc(nres)] = src[i];
}
}
int main(int argc, char **argv) {
int *data_to_filter, *filtered_data, nres = 0;
int *d_data_to_filter, *d_filtered_data, *d_nres;
data_to_filter = reinterpret_cast<int *>(malloc(sizeof(int) * NUM_ELEMS));
// Generate input data.
for (int i = 0; i < NUM_ELEMS; i++) {
data_to_filter[i] = rand() % 20;
}
findCudaDevice(argc, (const char **)argv);
checkCudaErrors(cudaMalloc(&d_data_to_filter, sizeof(int) * NUM_ELEMS));
checkCudaErrors(cudaMalloc(&d_filtered_data, sizeof(int) * NUM_ELEMS));
checkCudaErrors(cudaMalloc(&d_nres, sizeof(int)));
checkCudaErrors(cudaMemcpy(d_data_to_filter, data_to_filter,
sizeof(int) * NUM_ELEMS, cudaMemcpyHostToDevice));
checkCudaErrors(cudaMemset(d_nres, 0, sizeof(int)));
dim3 dimBlock(NUM_THREADS_PER_BLOCK, 1, 1);
dim3 dimGrid((NUM_ELEMS / NUM_THREADS_PER_BLOCK) + 1, 1, 1);
filter_arr<<<dimGrid, dimBlock>>>(d_filtered_data, d_nres, d_data_to_filter,
NUM_ELEMS);
checkCudaErrors(
cudaMemcpy(&nres, d_nres, sizeof(int), cudaMemcpyDeviceToHost));
filtered_data = reinterpret_cast<int *>(malloc(sizeof(int) * nres));
checkCudaErrors(cudaMemcpy(filtered_data, d_filtered_data, sizeof(int) * nres,
cudaMemcpyDeviceToHost));
int *host_filtered_data =
reinterpret_cast<int *>(malloc(sizeof(int) * NUM_ELEMS));
// Generate host output with host filtering code.
int host_flt_count = 0;
for (int i = 0; i < NUM_ELEMS; i++) {
if (data_to_filter[i] > 0) {
host_filtered_data[host_flt_count++] = data_to_filter[i];
}
}
printf("\nWarp Aggregated Atomics %s \n",
host_flt_count == nres ? "PASSED" : "FAILED");
checkCudaErrors(cudaFree(d_data_to_filter));
checkCudaErrors(cudaFree(d_filtered_data));
checkCudaErrors(cudaFree(d_nres));
free(data_to_filter);
free(filtered_data);
free(host_filtered_data);
}