glBindVertexArray going crazy [solved: OS / Driver issue]

[obi]

I'm just wondering if someone might have a clue to why glBindVertexArray can behave like this? Can I have initialized one or more of the VAOs in a bad way?

My case:

I am generating 3D terrain where every chunk is a mesh and has one VAO. The only difference between the profiling cases is that I have rendered one extra row of terrain chunks. For some reason glBindVertexArray goes crazy.

[Fool Running]

Your initialization and rendering code (maybe just the code that binds the buffer) would help.

[obi]

Debuging my lib gives:


17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glGenBuffers() => 7
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBindBuffer( ELEMENT_ARRAY_BUFFER, 7 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBufferData( ELEMENT_ARRAY_BUFFER, 80000, DYNAMIC_DRAW )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBufferSubData( ELEMENT_ARRAY_BUFFER, 0, java.nio.DirectByteBufferR[pos=0 lim=2352 cap=80000] )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBindBuffer( ELEMENT_ARRAY_BUFFER, 0 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glGenBuffers() => 8
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBindBuffer( ARRAY_BUFFER, 8 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBufferData( ARRAY_BUFFER, 108000, DYNAMIC_DRAW )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBufferSubData( ARRAY_BUFFER, 0, java.nio.DirectByteBuffer[pos=0 lim=19104 cap=108000] )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBindBuffer( ARRAY_BUFFER, 0 )

17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL30.glGenVertexArrays() => 3
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL30.glBindVertexArray( 3 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBindBuffer( ELEMENT_ARRAY_BUFFER, 7 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL15.glBindBuffer( ARRAY_BUFFER, 8 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL20.glVertexAttribPointer( 0, 3, 5126, false, 24, 0 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL20.glEnableVertexAttribArray( 0 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL20.glVertexAttribPointer( 4, 3, 5126, false, 24, 12 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL20.glEnableVertexAttribArray( 4 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL11.glDrawArrays( TRIANGLES, 1176, UNSIGNED_SHORT, 0 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL30.glBindVertexArray( 0 )


any calls to draw terrain meshes after the initialization is simply this


17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL30.glBindVertexArray( 3 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL11.glDrawArrays( TRIANGLES, 1176, UNSIGNED_SHORT, 0 )
17:35:01 [main] DEBUG obigl.lwjgl.OGL - GL30.glBindVertexArray( 0 )

[obi]

There is some very weird correlations to this issue arising when I have more than 255 meshes / VAOs visible during a frame.
I have to investigate further but right now it seems to weird to be a coincidence.

The thing is I know I have rendered with more than 255 VAOs every frame without problems so maybe it has to do with how many VAOs I can initialize during a single frame and not how many I display. Just speculation for now.

Edit: I have a 8800GTS with 512MB memory

[obi]

Yes it seems that as soon as I bind a VAO with an id bigger than 0xff(255) the glBindVertexArray call will spend more than 50-60% of all cpu time in kernel code. eg. red cpu usage in windows xp.

The thing is that I can use a lot of VAOs without any visual issues rendering. I know I have tried 1500 without problems.
On rare occasions I can render with 1000+ VAOs without spending most cpu time in kernel code. I have had this happen, that suddenly my app stops spending so much time in glBindVertexArray and my application runs smooth like a sport car! But this is pretty rare occasions.

I must figure out why so much time is spent in kernel code when running glBindVertexArray. Any suggestions how to debug this?

[obi]

I just upgraded to Windows 7 x64 from Windows XP x32.

This issue went away completely and the performance is awesome! It's actually so great I didn't expect to render realtime procedural terrain this fast on my old computer.

LWJGL really whips the llama's ass!