Uploading gpumat is too slow in jetson TX1

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Hi. I'm now working on jetson TX1 with cuda8.0. I compiled opencv3.1 with cuda and it looks successful.

However, when I tried some samples, I found cuda calclation pretty slow mostly because of uploading images.

For example, I tried surf feature extraction and matching from opencv sample cord. The result is like below:

upLoad = 39.9022

Device 0:  "NVIDIA Tegra X1"  3995Mb, sm_53, Driver/Runtime ver.8.0/8.0
FOUND 158 keypoints on first image
FOUND 137 keypoints on second image

Findcuda = 0.000123487  Extraction = 0.0952315
Matching = 0.00152424 Download = 0.00137919

This means uploading two images took about 40sec! Are there any solutions? Thank you.

I put my code here.

#include <iostream>

#include "opencv2/opencv_modules.hpp"

#ifdef HAVE_OPENCV_XFEATURES2D

#include "opencv2/core.hpp"
#include "opencv2/features2d.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/cudafeatures2d.hpp"
#include "opencv2/xfeatures2d/cuda.hpp"

using namespace std;
using namespace cv;
using namespace cv::cuda;

static void help()
{
    cout << "\nThis program demonstrates using SURF_CUDA features detector, descriptor extractor and BruteForceMatcher_CUDA" << endl;
    cout << "\nUsage:\n\tsurf_keypoint_matcher --left <image1> --right <image2>" << endl;
}

int main(int argc, char* argv[])
{
    if (argc != 5)
    {
        help();
        return -1;
    }

    GpuMat img1, img2;
    cv::Mat raw1,raw2;
    raw1 = imread(argv[2], IMREAD_GRAYSCALE);
    raw2= imread(argv[4], IMREAD_GRAYSCALE);
    int64 t0 = cv::getTickCount();
    for (int i = 1; i < argc; ++i)
    {
        if (string(argv[i]) == "--left")
        {
            img1.upload(raw1);
            CV_Assert(!img1.empty());
        }
        else if (string(argv[i]) == "--right")
        {
            img2.upload(raw2);
            CV_Assert(!img2.empty());
        }
        else if (string(argv[i]) == "--help")
        {
            help();
            return -1;
        }
    }

    int64 t1 = cv::getTickCount();
    cout <<  " upLoad = " << (t1-t0)/cv::getTickFrequency() << endl;

    cv::cuda::printShortCudaDeviceInfo(cv::cuda::getDevice());

    int64 t2 = cv::getTickCount();
    SURF_CUDA surf;

    // detecting keypoints & computing descriptors
    GpuMat keypoints1GPU, keypoints2GPU;
    GpuMat descriptors1GPU, descriptors2GPU;
    surf(img1, GpuMat(), keypoints1GPU, descriptors1GPU);
    surf(img2, GpuMat(), keypoints2GPU, descriptors2GPU);

    int64 t3 = cv::getTickCount();
    cout << "FOUND " << keypoints1GPU.cols << " keypoints on first image" << endl;
    cout << "FOUND " << keypoints2GPU.cols << " keypoints on second image" << endl;

        cout << " Findcuda = " << (t2-t1)/cv::getTickFrequency() << " Extraction = " << (t3-t2)/cv::getTickFrequency() << endl;

    // matching descriptors
    Ptr<cv::cuda::DescriptorMatcher> matcher = cv::cuda::DescriptorMatcher::createBFMatcher(surf.defaultNorm());
    vector<DMatch> matches;
    matcher->match(descriptors1GPU, descriptors2GPU, matches);
    int64 t4 = cv::getTickCount();

    // downloading results
    vector<KeyPoint> keypoints1, keypoints2;
    vector<float> descriptors1, descriptors2;
    surf.downloadKeypoints(keypoints1GPU, keypoints1);
    surf.downloadKeypoints(keypoints2GPU, keypoints2);
    surf.downloadDescriptors(descriptors1GPU, descriptors1);
    surf.downloadDescriptors(descriptors2GPU, descriptors2);
    int64 t5 = cv::getTickCount();


    cout <<  " Matching = " << (t4-t3)/cv::getTickFrequency() <<  " Download = " << (t5-t4)/cv::getTickFrequency() << endl;

    // drawing the results
    Mat img_matches;
    drawMatches(Mat(img1), keypoints1, Mat(img2), keypoints2, matches, img_matches);

    namedWindow("matches", 0);
    imshow("matches", img_matches);
    waitKey(0);

    return 0;
}

#else

int main()
{
    std::cerr << "OpenCV was built without xfeatures2d module" << std::endl;
    return 0;
}

#endif