I want to stress my application by rendering lots of polygons. I use DX12 (SharpDX) and I upload all vertices to GPU memory via an upload buffer. In normal cases everything works fine, but when I try to create a large upload buffer (CreateCommittedResource) I get a non-informative exception from SharpDX, and the device is being removed. GetDeviceRemovedReason (DeviceRemovedReason in SharpDX) returns 0x887A0020: DXGI_ERROR_DRIVER_INTERNAL_ERROR. 

I'm guessing it's all because it can't find a consecutive chunk of memory big enough to create the buffer (I have 6GB on the card and I'm currently trying to allocate a buffer smaller than 1GB).

So how do I deal with this? I guess I could create several smaller buffers instead, but I can't just put the CreateCommittedResource call in a try-catch section. The exception is serious enough to remove my device, so any further attempts will fail after the first try.

Can I somehow know beforehand what size is OK to allocate?

Sounds like the problem is coming from the driver. What driver(s) have you tried this on?

Ok, that's Interesting. I have a GeForce GTX 1060 6GB, driver version 390.65. Now that I upgraded to driver 398.11 I still get the same results.

So, I'm working my way around the problem by creating several small upload buffers, but I don't know at what size I should break and create another upload buffer. Too small buffers are not efficient, and too big will trigger the error. For now I just set the limit to around 100 Mb, and it works.

It may not help but googling in OpenGL reveals you may be able to do this:

GLint size;
glGetIntegerv(GL_MAX_SHADER_STORAGE_BLOCK_SIZE, &size);

and the docs suggest:

GL_MAX_SHADER_STORAGE_BLOCK_SIZE (64-bit integer, minimum is 2^24 (16,777,216)) The maximum size in basic machine units of a shader storage block.

I'm not suggesting you fire up OpenGL just to get the max size (it may be different anyway in DX) but I wouldn't be surprised if the same minimum size applied (16 megs).

That's what I do. It's just that I take a number (for maximum buffer size) out of thin air. It feels wrong, but it works.