I suppose this means it's going to run on multiple OSes, including linux and Google's Chrome OS?

excellant stuff, on a related note Ild never even heard of O3d until now

Congratulations! This is good news indeed.

Crysis has a major confound when judging D3D10 performance in the form of it's in-engine texture streamer. It's disabled at the lower two texture settings and kicks in at the higher two.

It is a major confound because DX10 already does a form of streaming of it's own in addition to the engine based one. Disabling texture streaming in the engine brings memory usage up to ~1.5gb in DX9 while remaining at 1gb in DX10 mode at the highest texture detail settings. The in-engine streamer also introduces artifacts so it becomes an apples-to-oranges scenario.

The same memory usage behavior is true of all DX10 games I've tried, but with nowhere near the performance drop. Far Cry 2, for example, drops from ~700mb to ~400mb going from DX9 to DX10 while still managing to perform faster.

Doesn't that have to do with the virtual videomemory system in D3D10 though?
From what I understood, in DX9 all texturememory is mapped into the virtual address space at all times. But with DX10 they aren't mapped into the address space at all unless you specifically Map() them...?

Can we stop with the video memory "virtualization" once and for all? It's been established as WDDM 2.x vaporware.

That's pretty much what I meant. What I was getting at (poorly, now that I re-read the post) was that because the game features an in-engine streamer you may have to control for it.

From what I understand, this built-in streaming engine was introduced to prevent the game from crashing at the 32-bit limit in DX9 mode at the higher texture settings. While I've never experienced it myself, I know that some setups can't run the game at full detail with streaming disabled for that reason. But while it's a fine solution to a DX9 issue, it's wholly unnecessary when running in DX10 while still being enabled by default. So, ideally, you'd want to disable in-engine texture streaming manually during testing (edit: setting textures to low or medium achieves the same result).

Don't get me wrong, I've never managed to get Crysis to run faster under DX10 than DX9 and I think it's definitely an engine issue. But if you want to test the actual rendering section of the engine (especially since you're using custom shaders) then you'd want to make sure that the streaming portion is disabled because it's a performance affecting workaround to an altogether unrelated problem.

wouldnt the crysis devs know about streaming in dx10 and disable it in preference of their own streaming
plus the 32bit limit in dx9 would surely still exist in dx10 (vista32)

Not if you only map memory when required.
As long as the CPU doesn't need to access the videomemory, there's no reason for it to take up address space on the CPU side.

All I know is that he has a point.
I have a PC with a Radeon X1900XTX, which reports WAY higher memory usage than when running Crysis on a GeForce 8800.
The Radeon goes over 1.5 GB, sometimes close to 2 GB, while the GeForce uses about 1 GB to 1.2 GB. I don't know what causes it, but the DX9 machine just uses way more memory than the DX10 one does, despite having higher detail.

How many times this is comes up again?

The typical video memory window is 256 MB. It needs to be mapped to the address space of any application that uses Direct3D. Vista is somewhat smarter here as it can dynamically change the size of the mapped window. But this can although cause crashes if the window needs to grow and there is no address space left.

When it comes to resource allocation Direct3D 9 and 10 behaves different.

10 is quite easy as any resource needs its own size of the address space. This is even true for textures that are in the video memory. The reason for this is that the virtual video memory manager must be able to swap the resource to the system memory. For different reasons they are swapped to the process that owns the resource.

9 is more complicated. Before SP1 any managed resource needs twice the address space. One time for the system memory copy and one time for the real video resource. This was done for compatibility reasons. But with graphics cards that contain a large amount of video memory and only 2 GB address space you run in problems. Therefore there was a hotfix that becomes part of SP1. This hotfix tries to eliminate the address space requirement for the real resource when possible. But it still needs more address space then 10.

I don’t have the exact numbers for BattleForge here but it requires significant less address space with Direct3D 10 compared to 9.