The effects of texture resolution on performance

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BusyBeaverHP

Limp Gawd
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Jun 22, 2009
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I know larger texture uses up more VRAM, but if VRAM is limitless, does increased texture size significantly impact GPU rendering performance?

I imagine that increasing the texture resolution would increase the fidelity of things like bump-maps, hence putting more rendering load on the GPU. I could be wrong, I have little understanding of this.

Suppose that you have a card like a 6GB Titan... assuming you kept resolution the same, and VRAM is not a bottleneck, what effect does increased texture size have on rendering and post-processing?
 
Im interested as well. I know absolutely nothing, however, I'd venture a guess that there would still be a delay of some kind due to memory bandwidth and such.
 
You still are limited by the memory controller bandwidth. Larger textures means more data is moving between the GPU and RAM. Even with endless RAM, you only have so many GB/s to work with. Often times the way GPU manufacturers slow down their cards is not by the GPU clock but by reducing the memory bandwidth or memory type.
 
Texture resolution is generally as close to free on modern hardware as you can hope to get, unless you manage to run out of VRAM. Mip mapping in turn also works well here, as it effectively makes sure you're not using needlessly large textures at distance, so you end up sampling from lower resolution versions ~* automagically *~.
 
It's reasonable to think of GPUs as sampling from textures and other surfaces as they draw out individual pixels in a frame. In that respect, texture resolution doesn't matter terribly: the executing shader understands the texture coordinate system and how to sample from it to rasterize pixels based on texture data, so it's essentially a constant time process.
 
Oh, okay, so it's definitely not like it used to be, where drawing the pixels meant essentially loading the whole texture. Interesting, so it is free, sort of, now. Good to know!
 
low, medium, high or very high textures have zero impact on Crysis 3 performance with my gtx660ti.
 
bigdogchris said:
You still are limited by the memory controller bandwidth. Larger textures means more data is moving between the GPU and RAM.
Click to expand...
Maybe I'm overlooking something, but aren't you taking the same number of texture samples regardless of the texture resolution?

Kai said:
Oh, okay, so it's definitely not like it used to be, where drawing the pixels meant essentially loading the whole texture.
Click to expand...
It does, but memory is cheap enough that it doesn't make a difference.
 
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