P3D5 HF1 VR crashing on second VR entry

[truthknown]

Hi guys.

So in P3D5 HF1, I am able to successfully load the sim at KJFK using DD's NYC and NY airports with the PMDG 748. Once loaded, I start VR and it works fine. If I turn off VR, still fine but once I enter VR the second time - Boom! DXGI error, sim crash. I have tried this 10 times, does the same thing each time. Night or day, doesn't matter. Super frustrating.

Since the entire experience unfortunately cannot be run in VR, there is always the need to be able to go in and out of VR, so this is again unusable.

Chris Lezama

[truthknown]

Bump!

Using Samsung Odyssey+ HMD, 1080Ti 11GB video card, 8700K processor. Any help would be appreciated!

Thanks,
Chris

[truthknown]

Tried this again today with the QWSIM 787. Tried to enter VR and got the crash every single time, on the first try. Over and over. I was using Single Pass mode.

Then I decided to see if Stereo mode would work, and boom, I was able to enter VR and go in and out.

So something is going wrong for me with Single Pass mode. Any help would be appreciated! Definitely want the higher frames it offers.

Chris

[truthknown]

Guess i'm going to get no response. $200 spent on a sim that I cant use the way I intended to. The way I was able to in v4. Great...

[jellef]

I am using a HP Reverb headset (Steam VR) and get DXGI_ERROR_DEVICE_HUNG errors whenever I use a bit more demanding scenery or aircraft. In non-VR mode I can use this scenario even in the highest graphics settings at nice frame rates, however when switching to VR almost immediately I get the error, or even worse a CTD. I have tried the 'stereo' setting instead of the 'single pass mode'. The rate of crashes improves a bit but it does not solve the real problem.

Another problem is that the popup after the DXGI error suggests that you can continue and at least save the scenario. This is definitely not true. In fact it's best to reboot and start allover. Not very nice!

I have been experimenting with many different settings, including using only the default P3D scenery and aircraft. Of course this improves the stability, but for this setting I did not buy this sim. Initially I was impressed by the upgrade from v4.5 to v5 with the improved graphics performance. Before HF1 the VR headset was useless, due to the bad synchronisation of R and L eyes. HF1 fixed this issue, but not the underlying problem. After many experiments I see that whenever the dedicated GPU memory comes near the maximum (RTX 2080 - 8GB), the DXGI error pops up. I never see an increase of the shared GPU usage, although I have plenty (16 GB). This leads to my conclusion that the graphics memory management does not do what it should and makes no good use of the available resources. I saw another topic on this forum indicating a simplified use of the new dirextX12 driver. Does this mean we deal with an unfinished development of this sim? It looks a bit like a quick and dirty solution.

In this state P3Dv5 HF1 is unusable in VR for me. I hope there will soon come a HF2 that tackles this bug.

Jelle

[truthknown]

Thanks for responding Jelle. I completely agree. As I test this more, its really coming down to the GPU memory usage. I have 32GB of RAM and its not being used in the Shared VRAM space at all. Every crash comes down to the sim hitting or coming close to the budgeted memory max. I believe entering VR is causing a short memory spike that hits the max budget almost immediately, though it would come down to a more manageable level once its finished regenerating the views in VR.

I am typically entering VR with 5-6 GB of VRAM in use by P3D with a 9.2GB budget. Many times that budget falls to 8.7GB and I don't know why, but regardless entering VR is causing an additional 3-4GB VRAM spike for me.

In all cases, VR or not, once that max budget is hit, the sim will crash with a DXGI error and in all cases it is unrecoverable. I would not want to fly a long commercial route here when I know the chances are the sim will crash on me at any point throughout the journey. That would be a monumental waste of time and I would be beyond frustrated. So I have never flown a planned flight in this sim yet. That is pretty sad given the amount spent on this thing...

Chris

[jellef]

Chris, I was surprised to see that your findings are so similar to mine! My system seems powerful enough to cope with all conditions in P3D and VR. Testing with other applications just proves it. And just like you I see that the dedicated GPU memory nears the limit of 8GB (the VRAM size of the RTX 2080), but never seems to actually touch it. GPU load is low at that time, CPU load is relatively low (usually cpu0 is near its max, most of the others are not).The crash almost always happens when switching from non-VR to VR or back. When lowering the graphics settings you see that after the switch to VR (when it does not crash) the memory usage stabilises to a lower value, so it seems to be only a momentary situation. For my VR headset Steam VR is used and this cleary contributes to the VRAM usage. Nevertheless, if I enable Steam before switching to VR the memory load does not rise so dramatically and it looks like the problem does not originate from the use of Steam.

I never see a clear increase in the shared GPU memory usage. In Windows Task Manager I see a total of 24 GB GPU memory available (8GB dedicated and 16 GB shared memory). I am not quite sure if this is the so called memory budget, but as far as I have investigated the DX12 API this seems to be right. It should not be my job to investigate why this error occurs, but it supports your and mine thoughts about what is wrong with P3Dv5. I found some very interesting Microsoft documents on DX12 memory management: https://docs.microsoft.com/en-us/window ... strategies . It describes that it allows the app to carefully manage physical memory. The memory budget section says: More explicit memory segment choice is available in Direct3D 12 (choosing between video and system memory). This suggests that the shared gpu memory can indeed contribute to the total available budget.

If you follow the link in the document to theQueryVideoMemoryInfo method, you find a remarks section explaining:
Applications must explicitly manage their usage of physical memory explicitly and keep usage within the budget assigned to the application process. My thoughts are that in the sim this is exactly where it goes wrong. Also interesting is the text of the DXGI_ERROR_DEVICE_HUNG error (follow the DXGI_Error link): The application's device failed due to badly formed commands sent by the application. This is an design-time issue that should be investigated and fixed.

I support your statement that this not only occurs in using VR, but with any heavy load of the GPU and/or VRAM. You can find many other posts on this forum describing a similar condition. It is unacceptable that this leads to an unrecoverable error. Especially if you use the sim for commercial purposes, but even if you're not, this is not how the product is promoted.

I hope anybody from the Prepard3d product development team gets involved in the discussion or at least clarifies the steps that are taken to solve the problem.

Jelle

[truthknown]

Bingo! You and I are completely aligned. I have a 1080Ti 11GB card however, running on a system with an 8700K CPU OC'd to 5 Ghz and 32GB RAM. I should in no way be having these issues and in P3D4, I am able to run the same settings with no problems at all. I sacrifice frame rates for the visuals I want, but that is the choice I live with. I hope that I do not need to turn down settings now just to use less VRAM in order to avoid the sim crashing...

With all you have found here, I do also believe this is a case of DirectX 12 being implemented incorrectly or inefficiently. P3D5 is clearly not managing the memory properly.

Let's hope that the dev team is able to figure out and correct the issues. Until then, P3D5 is completely unusable for me.

Chris