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CUDA Warp's Sum and Scan
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#include <stdio.h> | |
#include <thrust/device_vector.h> | |
#include <thrust/sequence.h> | |
__global__ | |
void warpSum(int *data) { | |
int idx = blockIdx.x * blockDim.x + threadIdx.x; | |
int value = data[idx]; | |
#pragma unroll | |
for (int i = 1; i < warpSize; i *= 2) | |
value += __shfl_xor(value, i); | |
printf("idx=%d\tvalue=%d\n", idx, value); | |
} | |
__global__ | |
void warpScan(int *data) { | |
int idx = blockIdx.x * blockDim.x + threadIdx.x; | |
int value = data[idx]; | |
int laneId = threadIdx.x % warpSize; | |
#pragma unroll | |
for (int i = 1; i < warpSize; i *= 2) { | |
int n = __shfl_up(value, i); | |
if (laneId >= i) value += n; | |
} | |
printf("idx=%d\tvalue=%d\n", idx, value); | |
} | |
int main() { | |
int warpSize = 32; | |
// warp sum | |
thrust::device_vector<int> A(warpSize); | |
thrust::sequence(A.data(), A.data() + warpSize); | |
warpSum<<<1, warpSize>>>(thrust::raw_pointer_cast(A.data())); | |
// warp scan | |
thrust::device_vector<int> B(warpSize); | |
thrust::sequence(B.data(), B.data() + warpSize); | |
warpScan<<<1, warpSize>>>(thrust::raw_pointer_cast(B.data())); | |
cudaDeviceSynchronize(); | |
return 0; | |
} |
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