Are GPUs presently used in AEFS2 for other calculations, including systems / fdm ?
No the graphics card renders the displays and the 3D model and scenery, the CPU is calculating the physics and a lot of other things. About a thousand per second as far as I know. There are other threads of the aerofly FS 2 engine that are running on multiple cores as well. Not just physics but also the preparation and selection of ground textures, loading scenery from disk and uploading content to the graphics card in the background, etc.
So each processor it's doing it's designed job in the Aerofly FS 2 engine.
It's immediately apparent when you open AFS2, that there is no bottleneck due to overloading of one or another subsystem.
Coming from the legacy sims, I was immediately struck by the fluidity of the experience.
I am curious as to what will eventually bring performance to its knees: High-res textures? Too many artifacts? Planes? Systems complexity?
Even though I have an almost-bleeding-edge computer there must be some limitation ultimately.
The graphics card performance decreases when you have more objects on the screen to render. This threshold is actually very high, the Aerofly FS 2 engine probably can render millions of houses without sacrificing 120FPS. What will bring it down are clouds, or at least if they aren't done right. Transparency is always a bit more tricky because then the order in which you render matters.
In terms of systems: As one of the IPACS systems developers I'm expecting fully developed study level aircraft to work without any performance issues, at least if we stick to the current way of implementing systems. Having outside scripts or libraries (DLLs) will slow it down more compared to a native implementation but the overall performance will probably remain fairly high. If you do it properly and share the load amongst the cores, only compute the things that need to be fast at a fast rate (1000x per second) and allow systems that are slow in the real world to be simulated slow (60x per second) as well (e.g. FMS, menus in a glass cockpit as an example) you can maintain a very good performance.
A detailled weather simulation could demand a lot of CPU performance for the detailled wind calculation and cloud formation. The more accurate you want the weather to be simulated the more you head into the direction of super-computers and actual weather forecast computations, so we have to pick the middle ground that is just right for the performance limits that we have. The graphics card would need to render a lot of clouds and fog as well, that isn't that "cheap" on the performance side either. I'm hoping we can get the lighting of the clouds just right so that is looks convicing.
To sum that up: Currently I don't see a performance limitation coming up. The engine has a lot of headroom right now, we can do a lot more systems and probably a lot more graphic features before we need to be concerned about performance. But we shouldn't be careless with the great headroom that we have we still have to optimize the new things.
An insightful read, thanks for that!
I did think weather might be the biggest potential issue - in my legacy sim flying out of Tolmachevo (despite being very far from anything else) with Real Russian Weather could cripple my computer.
The AFS2 engine does sound good, I hope it can stay "clean".
Thanks for the indeed insightful answer Jan !