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OpenGl slower and slower!


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#1 wugamp   Members   -  Reputation: 109

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Posted 26 July 2012 - 08:35 PM

I'm developing a 3D software with VC6 and OpenGL to simulate a rotating-eye, i.e. when I move the mouse I can see a machine from differnent view angle. However, if I keep rotating, It often gets slower and slower after running for about 10 mins. Sometimes it also gets dead.
I have worked for days but I can't solve it.
Now I think maybe the reason lies in video card driver.
Here is information of my environment:
GL_VENDOR: NVIDIA Corp.
GL_RENDERER: GeForce GT 430/PCIe/SSSE2/3DNOW!
GL_VERSION: 4.2.0
GLU_VERSION: 1.2.2.0 Microsoft Corp.
Do you think the environment is OK? Shall I re-intall the video card driver or change the option?
Or if you can give me some other suggestion?
Thanks a lot!

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#2 jefferytitan   Crossbones+   -  Reputation: 2162

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Posted 26 July 2012 - 09:09 PM

I would doubt that a driver would be so bad that it would have that effect. If so it would affect most other graphical applications as well.

Look out for memory leaks. You may be re-creating resources instead of re-using them, or failing to dispose of resources that you're legitimately finished with. I don't know your level of experience, but are you perhaps creating your mesh or textures multiple times?

PS - I'm not an expert on this but you may want to try something like gDEBugger to get statistics and info on leaks or obsolete APIs used.

Edited by jefferytitan, 26 July 2012 - 09:43 PM.


#3 Cornstalks   Crossbones+   -  Reputation: 6995

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Posted 26 July 2012 - 09:26 PM

I'm developing a 3D software with VC6

VC6? Really? I feel so bad for you... unless you are bringing this on yourself. You should seriously upgrade if you can. And if you can't, you should still upgrade. To anything.

However, if I keep rotating, It often gets slower and slower after running for about 10 mins. Sometimes it also gets dead.
I have worked for days but I can't solve it.

What have you tried? Could be a memory leak (those can have weird effects like this), or a number of things. It's likely a) a bug in your code, or b) a poor algorithmic choice.

Now I think maybe the reason lies in video card driver.
Here is information of my environment:
GL_VENDOR: NVIDIA Corp.
GL_RENDERER: GeForce GT 430/PCIe/SSSE2/3DNOW!
GL_VERSION: 4.2.0
GLU_VERSION: 1.2.2.0 Microsoft Corp.
Do you think the environment is OK? Shall I re-intall the video card driver or change the option?
Or if you can give me some other suggestion?

No clue... You'd be better off asking NVIDIA that. I'd be surprised if it's the driver, because you'd likely notice the issue in other programs too.
[ I was ninja'd 71 times before I stopped counting a long time ago ] [ f.k.a. MikeTacular ] [ My Blog ] [ SWFer: Gaplessly looped MP3s in your Flash games ]

#4 Garrett Hoofman   Members   -  Reputation: 307

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Posted 26 July 2012 - 09:27 PM

I would also lean toward a memory leak of some sort, or the re-creation of resources.

However, it could just be that the video card is slowing the frame rate down to 60 fps. Some video cards will do this as a way to save power. If that's the case you can verify it by monitoring the frame rate. It will have very distinct drops in frame rates and wont drop below 60 fps.

#5 Dir3kt   Members   -  Reputation: 166

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Posted 27 July 2012 - 01:36 AM

Mmh yeah what do you mean by slower and slower? Frame rate is going down (numbers) ?

As others said I doubt the problem is in driver/hardware.

How is the CPU/memory usage of your process evolving?

#6 wugamp   Members   -  Reputation: 109

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Posted 27 July 2012 - 02:01 AM

Thank you ALL! It's very possible that you are right. I checked the RAM with task-manager. The software snatches more and more RAM. At the beginning it occupies about 12M, then gradually increases to 18M.
Let me take Jeffery's tool to have a try.

#7 mhagain   Crossbones+   -  Reputation: 8006

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Posted 27 July 2012 - 03:17 AM

Increase to 18mb sounds normal enough, and an extra 6mb is a quite literally tiny amount of RAM for a program to be using - extremely unlikely to be causing any issues.

What are you using for timing in your code? Are you using a high-precision timer? Are you accumulating delta times (possibly as floats) each frame or are you using an absolute time-since-program-start?

It appears that the gentleman thought C++ was extremely difficult and he was overjoyed that the machine was absorbing it; he understood that good C++ is difficult but the best C++ is well-nigh unintelligible.


#8 larspensjo   Members   -  Reputation: 1541

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Posted 27 July 2012 - 03:35 AM

It could also be a memory leak of the GPU memory. For NVIDIA, try:
[source lang="cpp"]GLint par = -1;glGetIntegerv(GPU_MEMORY_INFO_CURRENT_AVAILABLE_VIDMEM_NVX, &par);printf("GPU_MEMORY_INFO_CURRENT_AVAILABLE_VIDMEM_NVX %d\n", par);[/source]
Current project: Ephenation.
Sharing OpenGL experiences: http://ephenationopengl.blogspot.com/

#9 wugamp   Members   -  Reputation: 109

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Posted 27 July 2012 - 05:19 AM

I still cannot use gDEBugger now. Now I'm working with a very stupid method: I remmed some sentences and observed task manager.
I found even glClear() can make memory-leak.
See the code:
void CModelDisplayDlg::RenderScene()
{
static float fShadMatrix[16];
float fShadowPlane[] = {0, 1, 0, 0};
float fLightDirect[] = {0, -1, 0, 0 };
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
SwapBuffers(m_hRenderDC);
}

Call RenderScene() again and again, and it will occupies more and more memory. But if I remmed glClear, it won't.

Maybe I don't use glClear properly?


to Mhagain: I timed with my mobile phone. In fact, I'm not interested in timing now. Task-manager helps more.

to Larspensjo: I have two computers with different video car. One is NVIDIA but the other is Interl® HD Graphics Family (maybe ATI).
Now I can only use the computer with Intel HD. GPU_MEMORY_INFO_CURRENT_AVAILABLE_VIDMEM_NVX doesn't work on it. Would you tell me some other name? Thanks for telling me the very useful method.

#10 larspensjo   Members   -  Reputation: 1541

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Posted 27 July 2012 - 07:11 AM

Would you tell me some other name?

On AMD, you can do:
[source lang="cpp"][/font][font=arial,helvetica,sans-serif]GLint parATI[4];glGetIntegerv(VBO_FREE_MEMORY_ATI, parATI);if (glGetError() == GL_NO_ERROR) printf("VBO_FREE_MEMORY_ATI total %d, largest block %d, total aux %d, largest aux block %d\n", parATI[0], parATI[1], parATI[2], parATI[3]);[/font][font=arial,helvetica,sans-serif][/source]
Notice the test with glGetError(), which can be used to make sure you got a result. I do that for the NVIDIA test also.
Current project: Ephenation.
Sharing OpenGL experiences: http://ephenationopengl.blogspot.com/

#11 Cornstalks   Crossbones+   -  Reputation: 6995

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Posted 27 July 2012 - 08:37 AM

to Mhagain: I timed with my mobile phone. In fact, I'm not interested in timing now. Task-manager helps more.

What? You said your program gets slower and slower. Which indicates it's taking more and more time to accomplish a given amount of work. Which means you should be interested in its timing behavior. How on earth are you timing with Task Manager? And how did you time it with your phone?? Can you exactly define what you mean by "slower and slower?"
[ I was ninja'd 71 times before I stopped counting a long time ago ] [ f.k.a. MikeTacular ] [ My Blog ] [ SWFer: Gaplessly looped MP3s in your Flash games ]

#12 jeff8j   Members   -  Reputation: 753

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Posted 27 July 2012 - 12:14 PM

Post the code the wild guesses are not helping but ill try some anyways
1. Are you using the old fixed pipeline approach (it could be phasing out driver wise because opengl is/did drop it)
2. VC6? common with all the hotpatches and crap over the years I wouldnt be surprised if just mentioning it leaked some memory
3. What kind of machine are you on? vc6, noticeable 6mb difference in memory, cant use the gdebugger?
4. How are you timing the frames in code and screen
5. Could just be your drawing code is off causing it to look slower and slower (get the fps)

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#13 mhagain   Crossbones+   -  Reputation: 8006

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Posted 27 July 2012 - 07:06 PM

Call RenderScene() again and again, and it will occupies more and more memory. But if I remmed glClear, it won't.

Maybe I don't use glClear properly?


This is normal behaviour. Your driver will build up some memory usage over the first few seconds/minutes, then settle down. You've got a bug in your code somewhere; it's nothing to do with your driver. You need to build up some accurate profiling results using a reliable timer, because right now you're just chasing ghosts. You basically have no reliable information to base any kind of conclusion about your program's performance on.

Edited by mhagain, 27 July 2012 - 07:10 PM.

It appears that the gentleman thought C++ was extremely difficult and he was overjoyed that the machine was absorbing it; he understood that good C++ is difficult but the best C++ is well-nigh unintelligible.


#14 wugamp   Members   -  Reputation: 109

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Posted 31 July 2012 - 01:12 AM

I worked with gDEBugger for the last two days and I found:
1. when my code gets "slower and slower", the value of "GDB GL Frames/sec" is between 0 and 1. That is, more then one frame per second.
2. At the same time, an information "Debug String: Warning: hDC is NULL in CWnd::GrayCtlColor; WM_CTLCOLOR not processed." shows in "Debugged Process Events" again and again.

#15 wugamp   Members   -  Reputation: 109

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Posted 31 July 2012 - 04:04 AM

I have almost solved the problem. I didn't ReleaseDC after GetDC. After adding ReleaseDC, my code can run for 30 minutes while the fps is always very high.
Thanks for everyone replied to the topic!




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