mirror of
https://github.com/NVIDIA/cuda-samples.git
synced 2024-10-06 20:29:18 +08:00
75 lines
2.8 KiB
Plaintext
75 lines
2.8 KiB
Plaintext
/* Copyright (c) 2021, 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.
|
|
*/
|
|
|
|
/*
|
|
* This example shows how to use the clock function to measure the performance
|
|
* of block of threads of a kernel accurately. Blocks are executed in parallel
|
|
* and out of order. Since there's no synchronization mechanism between blocks,
|
|
* we measure the clock once for each block. The clock samples are written to
|
|
* device memory.
|
|
*/
|
|
|
|
// This kernel computes a standard parallel reduction and evaluates the
|
|
// time it takes to do that for each block. The timing results are stored
|
|
// in device memory.
|
|
|
|
extern "C" __global__ void timedReduction(const float *input, float *output,
|
|
clock_t *timer) {
|
|
// __shared__ float shared[2 * blockDim.x];
|
|
extern __shared__ float shared[];
|
|
|
|
const int tid = threadIdx.x;
|
|
const int bid = blockIdx.x;
|
|
|
|
if (tid == 0) timer[bid] = clock();
|
|
|
|
// Copy input.
|
|
shared[tid] = input[tid];
|
|
shared[tid + blockDim.x] = input[tid + blockDim.x];
|
|
|
|
// Perform reduction to find minimum.
|
|
for (int d = blockDim.x; d > 0; d /= 2) {
|
|
__syncthreads();
|
|
|
|
if (tid < d) {
|
|
float f0 = shared[tid];
|
|
float f1 = shared[tid + d];
|
|
|
|
if (f1 < f0) {
|
|
shared[tid] = f1;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Write result.
|
|
if (tid == 0) output[bid] = shared[0];
|
|
|
|
__syncthreads();
|
|
|
|
if (tid == 0) timer[bid + gridDim.x] = clock();
|
|
}
|