Unexpected opencv performance on TK1, and CUDA crash

Robotics & Edge Computing Jetson Systems Jetson TK1
1

Hello developers,

I’m writing a simple piece of code which is trying to use the OpenCV 3.2.0 library’s CUDA optimised code to do some image processing. However, I got an unexpectedly poor performance on my TK1. Performing a box filter on a 4k by 1k image using kernel size of 5 runs for 0.017 seconds on CPU. I have tested the same box filter on GPU, but I got an unexpected execution time of 2 seconds. What’s worse is, when I tried to use a loop to filter 25 images, the GPU process got killed. This is rather poor. I have attached the code. Would you guys help me with this problem? I would be grateful if you could share me some docs on GPU programming.

In the code below, SPImage is a class I wrote for generating images containing random salt&pepper noise. Full code could be found in https://github.com/sthy14/TK1CV

#include "SPImage.hpp"
#include "omp.h"
#include <vector>
#include <opencv2/opencv.hpp>
#include <string>
#include <iostream>
#include <fstream>

#define NUMBER 1

using namespace cv;
using namespace std;

int main(int argc, char* argv[]) {
  cuda::DeviceInfo gpu;
  if (!gpu.isCompatible()) {
    cout << "GPU is not compatible\n";
    exit(-1);
  }
  SPImage generator;
  Mat image[25];
  for (int i = 0; i < NUMBER; i++) {
    image[i] = generator.Generate(4096, 1024);
    string fileName = "imgO" + to_string(i) + ".bmp";
    imwrite(fileName, image[i]);
  }
  cuda::GpuMat gImage[25];
  for (int i = 0; i < NUMBER; i++) {
    gImage[i].upload(image[i]);
  }
  Ptr<cuda::Filter> gpuBlur = cuda::createBoxFilter(CV_8UC1, CV_8UC1, Size(5, 5));
  Mat imageOut[25];
  cuda::GpuMat gOut[25];
  Mat gImageOut[25];
  Mat mpImageOut[25];

  double sStart = (double) getTickCount();
  for (int i = 0; i < NUMBER; i++) {
    blur(image[i], imageOut[i], Size(5, 5));
  }
  double sTime = ((double) getTickCount() - sStart) / getTickFrequency();
  cout << sTime << "\n";

  double mpStart = (double) getTickCount();
#pragma omp parallel for
  for (int i = 0; i < NUMBER; i++) {
    blur(image[i], mpImageOut[i], Size(5, 5));
  }
  double mpTime = ((double) getTickCount() - mpStart) / getTickFrequency();
  cout << mpTime << "\n";

  double gStart = (double) getTickCount();
  for (int i = 0; i < NUMBER; i++) {
    gpuBlur->apply(gImage[i], gOut[i]);
  }
  double gTime = ((double) getTickCount() - gStart) / getTickFrequency();
  cout << gTime << "\n";

  for (int i = 0; i < 25; i++) {
    gOut[i].download(gImageOut[i]);
  }

  for (int i = 0; i < NUMBER; i++) {
    // Output processed images.
    string sName = "imgS" + to_string(i) + ".bmp";
    string gName = "imgG" + to_string(i) + ".bmp";
    string mpName = "imgMP" + to_string(i) + ".bmp";
    imwrite(sName, imageOut[i]);
    imwrite(gName, gImageOut[i]);
    imwrite(mpName, mpImageOut[i]);
  }
}

Kind regards,

Dawen

2

Hi,

Thanks for your question.
Could you maximize the cpu/gpu frequency and try it again.

sudo ./tegrastats

Thanks.

3

Hi,

Thank you for your reply. I followed the instructions in [url]http://elinux.org/Jetson/Performance[/url] to set the performance. The performance of GPU is slightly better, the blurring time decreases from 2sec to 1sec. However, this is still far more than CPU process(0.015s). Are there any other tunes I could try, or any guides I could follow?

Thanks.

4

Could you make a previous call to gpublur before your gpu measurement loop ?

<b>gpuBlur->apply(gImage[0], gOut[0]);</b>
double gStart = (double) getTickCount();
...

I use to experience long delay for the first call. Seems it takes time to load/initialize everything (cuda/opencv/…). This setup time is also variable, making latency measurements not repeatable.

If someone knows a clean way to get everything ready, please share.

[EDIT: you may also have a look to http://stackoverflow.com/questions/31523216/opencv-gpu-blurring-is-slow ]