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https://github.com/NVIDIA/cuda-samples.git
synced 2026-10-25 22:28:17 +08:00
Apply consistent code formatting across the repo. Add clang-format and pre-commit hooks.
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@@ -48,43 +48,46 @@
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// This kernel computes a standard parallel reduction and evaluates the
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// time it takes to do that for each block. The timing results are stored
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// in device memory.
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__global__ static void timedReduction(const float *input, float *output,
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clock_t *timer) {
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// __shared__ float shared[2 * blockDim.x];
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extern __shared__ float shared[];
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__global__ static void timedReduction(const float *input, float *output, clock_t *timer)
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{
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// __shared__ float shared[2 * blockDim.x];
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extern __shared__ float shared[];
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const int tid = threadIdx.x;
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const int bid = blockIdx.x;
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const int tid = threadIdx.x;
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const int bid = blockIdx.x;
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if (tid == 0) timer[bid] = clock();
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if (tid == 0)
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timer[bid] = clock();
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// Copy input.
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shared[tid] = input[tid];
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shared[tid + blockDim.x] = input[tid + blockDim.x];
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// Copy input.
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shared[tid] = input[tid];
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shared[tid + blockDim.x] = input[tid + blockDim.x];
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// Perform reduction to find minimum.
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for (int d = blockDim.x; d > 0; d /= 2) {
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__syncthreads();
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if (tid < d) {
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float f0 = shared[tid];
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float f1 = shared[tid + d];
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if (f1 < f0) {
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shared[tid] = f1;
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}
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}
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}
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// Write result.
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if (tid == 0)
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output[bid] = shared[0];
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// Perform reduction to find minimum.
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for (int d = blockDim.x; d > 0; d /= 2) {
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__syncthreads();
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if (tid < d) {
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float f0 = shared[tid];
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float f1 = shared[tid + d];
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if (f1 < f0) {
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shared[tid] = f1;
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}
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}
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}
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// Write result.
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if (tid == 0) output[bid] = shared[0];
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__syncthreads();
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if (tid == 0) timer[bid + gridDim.x] = clock();
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if (tid == 0)
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timer[bid + gridDim.x] = clock();
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}
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#define NUM_BLOCKS 64
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#define NUM_BLOCKS 64
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#define NUM_THREADS 256
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// It's interesting to change the number of blocks and the number of threads to
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@@ -104,50 +107,46 @@ __global__ static void timedReduction(const float *input, float *output,
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// the memory. With more than 32 the speed scales linearly.
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// Start the main CUDA Sample here
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int main(int argc, char **argv) {
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printf("CUDA Clock sample\n");
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int main(int argc, char **argv)
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{
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printf("CUDA Clock sample\n");
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// This will pick the best possible CUDA capable device
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int dev = findCudaDevice(argc, (const char **)argv);
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// This will pick the best possible CUDA capable device
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int dev = findCudaDevice(argc, (const char **)argv);
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float *dinput = NULL;
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float *doutput = NULL;
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clock_t *dtimer = NULL;
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float *dinput = NULL;
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float *doutput = NULL;
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clock_t *dtimer = NULL;
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clock_t timer[NUM_BLOCKS * 2];
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float input[NUM_THREADS * 2];
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clock_t timer[NUM_BLOCKS * 2];
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float input[NUM_THREADS * 2];
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for (int i = 0; i < NUM_THREADS * 2; i++) {
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input[i] = (float)i;
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}
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for (int i = 0; i < NUM_THREADS * 2; i++) {
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input[i] = (float)i;
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}
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checkCudaErrors(
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cudaMalloc((void **)&dinput, sizeof(float) * NUM_THREADS * 2));
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checkCudaErrors(cudaMalloc((void **)&doutput, sizeof(float) * NUM_BLOCKS));
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checkCudaErrors(
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cudaMalloc((void **)&dtimer, sizeof(clock_t) * NUM_BLOCKS * 2));
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checkCudaErrors(cudaMalloc((void **)&dinput, sizeof(float) * NUM_THREADS * 2));
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checkCudaErrors(cudaMalloc((void **)&doutput, sizeof(float) * NUM_BLOCKS));
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checkCudaErrors(cudaMalloc((void **)&dtimer, sizeof(clock_t) * NUM_BLOCKS * 2));
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checkCudaErrors(cudaMemcpy(dinput, input, sizeof(float) * NUM_THREADS * 2,
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cudaMemcpyHostToDevice));
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checkCudaErrors(cudaMemcpy(dinput, input, sizeof(float) * NUM_THREADS * 2, cudaMemcpyHostToDevice));
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timedReduction<<<NUM_BLOCKS, NUM_THREADS, sizeof(float) * 2 * NUM_THREADS>>>(
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dinput, doutput, dtimer);
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timedReduction<<<NUM_BLOCKS, NUM_THREADS, sizeof(float) * 2 * NUM_THREADS>>>(dinput, doutput, dtimer);
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checkCudaErrors(cudaMemcpy(timer, dtimer, sizeof(clock_t) * NUM_BLOCKS * 2,
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cudaMemcpyDeviceToHost));
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checkCudaErrors(cudaMemcpy(timer, dtimer, sizeof(clock_t) * NUM_BLOCKS * 2, cudaMemcpyDeviceToHost));
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checkCudaErrors(cudaFree(dinput));
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checkCudaErrors(cudaFree(doutput));
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checkCudaErrors(cudaFree(dtimer));
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checkCudaErrors(cudaFree(dinput));
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checkCudaErrors(cudaFree(doutput));
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checkCudaErrors(cudaFree(dtimer));
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long double avgElapsedClocks = 0;
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long double avgElapsedClocks = 0;
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for (int i = 0; i < NUM_BLOCKS; i++) {
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avgElapsedClocks += (long double)(timer[i + NUM_BLOCKS] - timer[i]);
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}
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for (int i = 0; i < NUM_BLOCKS; i++) {
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avgElapsedClocks += (long double)(timer[i + NUM_BLOCKS] - timer[i]);
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}
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avgElapsedClocks = avgElapsedClocks / NUM_BLOCKS;
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printf("Average clocks/block = %Lf\n", avgElapsedClocks);
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avgElapsedClocks = avgElapsedClocks / NUM_BLOCKS;
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printf("Average clocks/block = %Lf\n", avgElapsedClocks);
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return EXIT_SUCCESS;
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return EXIT_SUCCESS;
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}
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