Sign in to follow this  

Slow performance of rendering quads in D3D if using big vertex buffer

This topic is 2127 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi Team,
I have an performance issue with 5770 ATI card with the latest drivers and with windows7 32 bits:
The program does the following :
It has a VertexBuffer, which is dynamic : D3DUSAGE_DYNAMIC|D3DUSAGE_WRITEONLY, D3DPOOL_DEFAULT
Assume I need to render 50K quads. Assume the buffer capacity is N quads.
How do I render :
SetTexture(0, t);
for (1..50k/N) {
LockEntireBuffer(D3DLOCK_DISCARD);
Fill The Buffer With Quads Data
Unlock();
DrawIndexedPrimitive();
}
The problem is following:
When the vertex buffer is really small ( <4kbyte) (42 quads * 24 bytes per vertex) then rendering is very fast (lets say 64 fps, no-v-sync);
When the buffer 2x times more then 4k the rendering become very slow : 43 fps,
When buffer grows to 96k (1024 quads) then fps slowly grows up to 57 FPS.
Our profiling tells that when sizeof the buffer exceeded 4k, the program starts spending too much time in D3DKMTLock.
The problem is not reproducible when we change textures frequently :
for (..) {
LockEntireBuffer(D3DLOCK_DISCARD);
Fill The Buffer With Quads Data
Unlock();
for (...) {
SetTexture(t[i]);
DrawIndexedPrimitive(part of the buffer);
}
}
In that situation : the bigger buffer is, the faster it renders.
What am I doing wrong ? Why do we have very significant boos with dynamic buffers less then 4k ?
Thanks

Share this post


Link to post
Share on other sites

This topic is 2127 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this