udateGL() with Nvidia&ATI

Hi,

my situation is following:

I write an app that have one QWidget. This widtget contains between 9 and 12 custom QGLWidget. Every custom QGLWidget get every 40 ms an image from a worker(which works in his one thread). I use PBO to copy imgaes in textur. And I use following connects:

Code:

---

connect(mCam, SIGNAL(renderedImage(const QImage &)), this, SLOT(updateTextur(const QImage &)));
    QTimer *timer = new QTimer();
    timer->start(40);
    connect(timer,SIGNAL(timeout()),this,SLOT(updateGL()),Qt::DirectConnection);

---

updateTextur is simple:

Code:

---

void OpenGLWidget::updateTextur(const QImage &image)
{
    if(image.byteCount() > 0)
    {
        mImg = QImage(image);
 
    }
}

---

Furthermore, I stop Time between painGL's invocation. And I get 47 ms with ATI and over 100 ms with NVidia!

Have sombody an idea why?

thanks!

Change byteCount() to isNull() and see if it changes anything. Apart from that - use a profiler to see where the bottle-neck of your application is.

Thank you for Answer!

I replaced byteCount() by isNull(), and I already profiled my app, But I can't find any bottle-neck.

But I saw some other problems:
My rozessor works with 50%, but if I put other window from other app over my app, than my app works with 20% and it stay on 20% if i do ohter window off.
If I put ohter window over half of my window, than I get better stop time (60 ms)

It is very strange! With ATI it works realy fine, but with NVIDIA come this Problems.

Somebody an idea?

thanks!

Quote:

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Originally Posted by bahbah30

and I already profiled my app, But I can't find any bottle-neck.

---

Then it means you didn't profile you app. There is always a bottle-neck, it's nothing to be "found" really, it's the code path taking the most time.

Quote:

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But I saw some other problems:
My rozessor works with 50%,

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You probably have two cores in your machine and the application uses only one. Do you use threads in your app?

Quote:

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but if I put other window from other app over my app, than my app works with 20%

---

Less to calculate/display.

Quote:

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and it stay on 20% if i do ohter window off.

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I can't explain that.

Quote:

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If I put ohter window over half of my window, than I get better stop time (60 ms)

---

Less to calculate/display.

I used gprof to profile my app, but i found nothing, becouse my app is multithreded. And I use minGW. So I can't profile my app.

I have main.cpp and 3 other classes. Worker is in itsown thread. In main-tread is my MainWindows and my OpenGLWidget. OpenGLWidget will be shown between 9 and 12 times in MainWindow. If is stop time in painGL using QTime:

Code:

---

void OpenGLWidget::paintGL()
{
        endTime1= t1.elapsed();//rest of the time
        t.start();
        paint();//openGL code
        endTime = t.elapsed(); //within paintGL
        t1.start();
}

---

endTime ist always 0. But the endTime1 is between 40 and 160 ms(with 12 widgets ) or 40 and 120 ms (with 9 widgets). But i do nothing in the rest of time. If I execute the same binary on ATI I get expected time (40 ms) Because :

Code:

---

QTimer *timer = new QTimer();
timer->start(40);
connect(timer,SIGNAL(timeout()),this,SLOT(updateGL()),Qt::DirectConnection);

---

Use QT driver specific way to show an app?

thanks!

Quote:

---

Originally Posted by bahbah30

I used gprof to profile my app, but i found nothing, becouse my app is multithreded. And I use minGW. So I can't profile my app.

---

There is more than one profiling tool in the world.

So what do the threads do?

In general your application is eating up a lot of cpu power because you're repainting it constantly (even when there is nothing to repaint).

Quote:

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Originally Posted by wysota

There is more than one profiling tool in the world..

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Do you know one non commercial that works with minGW on windows (with multitreadinbg support)?

Quote:

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Originally Posted by wysota

So what do the threads do?.

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It encapsulates ffmpeg to decode Video and emits QImage as Signal.

Quote:

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Originally Posted by wysota

In general your application is eating up a lot of cpu power because you're repainting it constantly (even when there is nothing to repaint)

---

I Know, but the question ist still, why it works fine on ATI and so bad on NVIDIA?

Thanks!

Quote:

---

Originally Posted by bahbah30

Do you know one non commercial that works with minGW on windows (with multitreadinbg support)?

---

I'm not that fond of Windows, sorry. You can run linux as a virtual machine and use Valgrind. That's the best profiling tool available. As for gprof, I know it can handle threads at least on Linux with a bit of tweaking. Moreover you can rem out the thread for now and emit bogus data - then you'll be able to use gprof directly.

Quote:

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It encapsulates ffmpeg to decode Video and emits QImage as Signal.

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Can we see the code and the connect statement using the signal?

Quote:

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I Know, but the question ist still, why it works fine on ATI and so bad on NVIDIA?

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You'd have to ask ATI and NVIDIA, their GL drivers are proprietary :) Nobody will be able to tell you the exact code paths used in both cases.

I suggest you start by getting rid of the timer and updating the widget when something really changes in it.

Hi,

now I have minimal exmaple of the problem as Attachment.Attachment 5821

If I do following:

Code:

---

OpenGLWidget::OpenGLWidget( QWidget *parent):
        QGLWidget(parent)
{
    QTimer *mTimer = new QTimer();
    mTimer->start(40);
    connect(mTimer,SIGNAL(timeout()),this,SLOT(updateGL()));
}

---

I expect, that I get 40 as result of invoking this:

Code:

---

void OpenGLWidget::paintGL()
{
    int a = t.elapsed();
    t.start();
    qDebug()<<"Time out of painGL: "<<a;
}

---

but it comes every thing, but not 40 ms.

thanks!

I would expect everything but 40ms.

I got it!

It was "vsync". I disabled vsync and it works how expected.

@wysota: Thank you that you tried to find a solution (dziękuję)