active P3D v5 and VRAM comments

[CZZ]

FYI:

VRAM is VideoRAM, aka didicated RAM on a video card

From: https://forums.flightsimlabs.com/index.php?/topic/25234-beware-of-vram-usage-in-p3d-v5/
The problem isn't with the gpus. nVidia 10 and 11 series cards are more than capable of handling all the modern graphics apis. It's with the way the new graphics API's work.
There is a video floating around where Austin Myer essentially explains the same concerns in X-Plane when running on Vulkan.

DX12 and Vulkan are both newer graphics api's that work at a much lower level on the graphics card than earlier Direct X versions (for P3D / FSX) and OpenGL (for X-plane).

They offer performance gains because they allow developers to load graphics textures directly into GPU memory rather than having to load them into slower system memory (RAM) and developers can also take advantage of other functions in the new api's that reduce cpu overheads when processing "draw calls". All these things reduce the amount of CPU processing required compared with the previous versions of the API's. The freed up CPU cycles and the faster processing of textures by the video card is what is resulting in the increased performance we see in v5.

However, because developers are now working much closer to the graphics hardware (e.g. loading textures directly into GPU memory), they now must be much more aware of how much VRAM each texture requires and they must manage the VRAM directly themselves. Previous API's did the memory management for them as the textures were in system memory and the graphics API took care of swapping textures to VRAM as and when required. The developers didn't have to worry about the amount of free VRAM and the API managed all that for them. However, the older API's had lower performance since they took up valuable CPU processing time and waited for textures to be moved back and forward between system RAM and VRAM.

It seems that with P3Dv5 it is going to be the end user's responsibility not to load too many textures to exceed their available VRAM. LM doesn't appear to have taken any measures in their code to prevent this from happening. I've had one crash to desktop on my machine so far. Not 100% it was a lack of VRAM as I didn't investigate it too much, but I run at 4K with 4x Super Sampling AA (I use a 65" screen so AA is important) and all graphics and world settings maxed out except dynamic reflections. GPU is the 2080Ti.

I'm prepared for the fact that I might have to drop a few notches once the FSLabs is released. Not because of performance reasons, as I get superbly fluid performance with FSL, but because I might see the VRAM being exceeded from time to time.

Other comments:
P3D V4.5 does not use DX12.

Apparently, per the Internet, there is a 16.25% reduction in the amount of VRAM that the sim can use.
Re: my Nvidia 1060 with 6 GB ram
16.25% reduction = .975GB
So, v5 can only use 5 GB, and per Shift_Z keys twice: “GPU Memory: 3.6/5 GB”
And, v5 is currently using 3.6 GB

Per the Internet: "I have found that the two biggest VRAM hogs are Advanced Atmospherics (TrueSky Beta) and Texture Resolution."
Re: my tests:
Advanced Atmospherics setting for San Jose, CA airport departure:
On: 4.5 GB
Off: 3.4 GB

[FlightsWithJoel]

Thanks you for the explanation. So, it seems we went from barley making use of GPU, to using GPU almost exclusively. My 1080 is using 7GB in Honolulu. The solution is to turn things down (go backwards) form 4.5. Harrumph.

[FreeBird]

VRAM is going to be the next Achilles heal in this hobby.