asyncapi.cu

来自「CUDA开发计算」· CU 代码 · 共 139 行

/*
 * Copyright 1993-2007 NVIDIA Corporation.  All rights reserved.
 *
 * NOTICE TO USER:
 *
 * This source code is subject to NVIDIA ownership rights under U.S. and
 * international Copyright laws.  Users and possessors of this source code
 * are hereby granted a nonexclusive, royalty-free license to use this code
 * in individual and commercial software.
 *
 * NVIDIA MAKES NO REPRESENTATION ABOUT THE SUITABILITY OF THIS SOURCE
 * CODE FOR ANY PURPOSE.  IT IS PROVIDED "AS IS" WITHOUT EXPRESS OR
 * IMPLIED WARRANTY OF ANY KIND.  NVIDIA DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOURCE CODE, INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE.
 * IN NO EVENT SHALL NVIDIA BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL,
 * OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
 * OF USE, DATA OR PROFITS,  WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION,  ARISING OUT OF OR IN CONNECTION WITH THE USE
 * OR PERFORMANCE OF THIS SOURCE CODE.
 *
 * U.S. Government End Users.   This source code is a "commercial item" as
 * that term is defined at  48 C.F.R. 2.101 (OCT 1995), consisting  of
 * "commercial computer  software"  and "commercial computer software
 * documentation" as such terms are  used in 48 C.F.R. 12.212 (SEPT 1995)
 * and is provided to the U.S. Government only as a commercial end item.
 * Consistent with 48 C.F.R.12.212 and 48 C.F.R. 227.7202-1 through
 * 227.7202-4 (JUNE 1995), all U.S. Government End Users acquire the
 * source code with only those rights set forth herein.
 *
 * Any use of this source code in individual and commercial software must
 * include, in the user documentation and internal comments to the code,
 * the above Disclaimer and U.S. Government End Users Notice.
 *
 *
 * This sample illustrates the usage of CUDA events for both GPU timing and
 * overlapping CPU and GPU execution.  Events are insterted into a stream
 * of CUDA calls.  Since CUDA stream calls are asynchronous, the CPU can
 * perform computations while GPU is executing (including DMA memcopies
 * between the host and device).  CPU can query CUDA events to determine
 * whether GPU has completed tasks.
 *
*/

#include <stdio.h>
#include <cutil.h>

__global__ void increment_kernel(int *g_data, int inc_value)
{ 
   int idx = blockIdx.x * blockDim.x + threadIdx.x;
   g_data[idx] = g_data[idx] + inc_value;
}


int correct_output(int *data, const int n, const int x)
{
    for(int i = 0; i < n; i++)
        if(data[i] != x)
            return 0;
    return 1;
}

int main(int argc, char *argv[])
{
    CUT_DEVICE_INIT(argc, argv);

    int n = 16 * 1024 * 1024;
    int nbytes = n * sizeof(int);
    int value =26;

#ifdef __DEVICE_EMULATION__
    n = 1024;   // reduce workload for emulation
#endif
    
    // allocate host memory
    int *a = 0;
    CUDA_SAFE_CALL( cudaMallocHost((void**)&a, nbytes) );
	memset(a, 0, nbytes);
      //printf("nbytes is %d\n",nbytes);//I  want to see the value of nbytes
    // allocate device memory
    int *d_a=0;
    CUDA_SAFE_CALL( cudaMalloc((void**)&d_a, nbytes) );
    CUDA_SAFE_CALL( cudaMemset(d_a, 255, nbytes) );

    // set kernel launch configuration
    dim3 threads = dim3(512, 1);
    dim3 blocks  = dim3(n / threads.x, 1);

    // create cuda event handles
    cudaEvent_t start, stop;
    CUDA_SAFE_CALL( cudaEventCreate(&start) );
    CUDA_SAFE_CALL( cudaEventCreate(&stop)  );
    
    unsigned int timer;
    CUT_SAFE_CALL(  cutCreateTimer(&timer)  );
    CUT_SAFE_CALL(  cutResetTimer(timer)    );
    CUDA_SAFE_CALL( cudaThreadSynchronize() );
    float gpu_time = 0.0f;

    // asynchronously issue work to the GPU (all to stream 0)
        CUT_SAFE_CALL( cutStartTimer(timer) );
        cudaEventRecord(start, 0);
        cudaMemcpyAsync(d_a, a, nbytes, cudaMemcpyHostToDevice, 0);
        increment_kernel<<<blocks, threads, 0, 0>>>(d_a, value);
        cudaMemcpyAsync(a, d_a, nbytes, cudaMemcpyDeviceToHost, 0);
        cudaEventRecord(stop, 0);
    CUT_SAFE_CALL( cutStopTimer(timer) );

    // have CPU do some work while waiting for stage 1 to finish
    unsigned long int counter=0;
    while( cudaEventQuery(stop) == cudaErrorNotReady )
    {
        counter++;
    }
    CUDA_SAFE_CALL( cudaEventElapsedTime(&gpu_time, start, stop) );

    // print the cpu and gpu times
    printf("time spent executing by the GPU: %.2f\n", gpu_time);
    printf("time spent by CPU in CUDA calls: %.2f\n", cutGetTimerValue(timer) );
    printf("CPU executed %d iterations while waiting for GPU to finish\n", counter);

    // check the output for correctness
    printf("--------------------------------------------------------------\n");
    if( correct_output(a, n, value) )
        printf("Test PASSED\n");
    else
        printf("Test FAILED\n");

    // release resources
    CUDA_SAFE_CALL( cudaEventDestroy(start) );
    CUDA_SAFE_CALL( cudaEventDestroy(stop) );
    CUDA_SAFE_CALL( cudaFreeHost(a) );
    CUDA_SAFE_CALL( cudaFree(d_a) );

    CUT_EXIT(argc, argv);

    return 0;
}