How to avoid VRAM fragmentation?

Question

I realize there's no way to avoid it for certain , as OpenGL says nothing about VRAM fragmentation.

But all the same, I have fragmentation in my app and I want to try reducing it on common platforms.

The only thing I found on the topic was this :

The best way to prevent heavy memory fragmentation is to try to and restrict the amount of varying resolutions in a project. When an asset is swapped out for one that is the same resolution, often times it can take it's place in the memory.

Which makes a lot of sense.

Is it really a good idea? And are there other things to keep in mind about this?

Note that in my usecase virtually all my VRAM usage consists of textures (and the back/front/depth buffers). Hardly any is buffer objects and such.

Answer 1

Basically you are right. Out of all the resources texture is heavy one. Not only you can use textures as buffers but as normal images also. Plus you can have multiple resolutions of same texture. You have to remember on driver side there are certain criteria that makes the resource to loaded in GPU ram or unload. So if you have textures with same resolution. Even if one of it is unloaded its memory block can be allocated to other without any fragmentation. Also when you create texture or any resource for that matter you cant be sure the memory is present in GPU Ram. It could be any where based on Driver implementation. Also during the lifetime of the resource driver might move that resource from one memory to other. Other than that at least in OpenGL you dont have any control over different memories and how they are allocated. Hence Vulkan is preferred in such cases when you need more control and you know what you are doing as you can specify not only type of memory you want but also you can specify your own allocators for that memory.