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[INVESTIGATING]DCS Causing SteamVR Fail | Description, evidence and how to replicate


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This post is 1) a description of an issue that has been plaguing DCS VR for at least two patches now. 2) Overview of how to replicate for ED 3) link to the mission file used in the video 4) Things I’ve already tried

 

[YOUTUBE]v0ootTLNbdI[/YOUTUBE]

 

Video Link:

The left side is the direct feed from my HMD, the right is a desktop capture to see what the crash looks like. In the video, after the crash the (left) HMD view seems to just freeze. That is just how its captured, it's very much turning off/going black when the fail message pops up

 

Timestamps:

2:00 is where I get into the game and fly around for just a bit.

3:18 I start intentionally making it mad

4:10 Crash is called out, HMD goes blank when the error pops up (just freezes in video)

 

 

Issue Description

DCS is seemingly causing VR HMDs to turn off, leaving DCS running but giving a fail in the VR client (steam) or just outright closing (Oculus). This has happened to me on virtually every map at this point, I used Syria because it’s fairly heavy and I can trigger the issue on it like clockwork.

 

My speculation is this has to do with when a lot of things are moving into/out of RAM. This is more common with SteamVR, but I’ve been able to replicate this with the Rift S as well.

 

How to replicate

 

Leading with the assumption made about RAM I/O, using the Syria map (although PG would work as well), and swapping between modules/F-10 will usually cause the crash as shown in the video. One of my friends put it perfectly when he says “There is a 60% chance if I hit F-10 on Syria that my VR will shut off.” The most egregious example of this was going quickly from the Syria map itself, quitting and opening the mission editor for a Nevada map caused the issue. In summary:

 

• Using the F-10 map, especially if toggling quickly

• Switching modules, especially to the F-14 and ESPECIALLY when it’s on the Super Carrier

• Bringing up the VR overlay (Steam or Oculus)

 

“But this doesn’t happen to me / I've not had any problems”

This seems to only happen on missions/servers where the game is stressed and moving a lot of things into and out of memory. This is exacerbated by 1) using the F10 map 2) Switching modules, especially to the F-14 + Super Carrier and 3) Bringing up VR overlay (Steam). Chances are very good if you are not using multiplayer, or even missions with a lot of memory I/O this will not happen to you. I actually thought I'd fixed the issue when I went for about two weeks with only doing single player and lightweight 1v1 instant actions.

 

“This is probably Steam, your HMD, your CPU etc., not DCS”

 

Believe me, I thought so too. In fact, I suspect a LOT of people that are impacted by this are making that assumption. Between the small group of people, I usually fly with, some random people’s comments in multiplayer chat and the FoH tournament voice chat, this issue is not uncommon and most folks think it is their HMD/CPU/Steam so they are not reporting it.

 

So how do I know this is DCS? I don’t, but if I combine all the steps I’ve done below to troubleshoot with uptick of similar issues being reported by others in the linked threads along with the demonstrated replication should hopefully at least present a case for ED to look into it.

 

Things I’ve tried already

 

Look, I get it you have to do all the “make sure it’s plugged in” steps, hopefully between the video, steps I’ve outlined below and the threads showing multiple other people having this issue we can quickly move past the basics.

Disclaimer: My CPU/GPU/RAM are not overclocked, nor is there any notable heat issues presenting on either system.

 

• Have tried this on two different computers

• Happens on both Oculus Rift S and Index, albeit the Rift S it’s less frequent

• Have tried different USB/Display ports

• Closing SRS / running a virgin (repaired, no mods) instance of DCS

• Drivers/Windows/DCS all running latest versions, this problem has existed through at least 2x updates of both drivers and DCS. Switching Steam between stable/OB doesn’t matter, as mentioned this will happen on the Rift S as well (running native Oculus SDK)

 

Someone is going to inevitably say you need to update _______, turn off ______, it’s your _______. Ask yourself this before offering such advice, “Would a different HMD and/or test system invalidate my suggestion?” If the answer is yes, consider it invalidated :)

 

Reference threads (People having the same problem):

 

https://forums.eagle.ru/showthread.php?p=4472903

https://forums.eagle.ru/showthread.php?t=231473

https://forums.eagle.ru/showthread.php?t=267004&highlight=crash

 

Attachments:

  • Mission used in the video
  • Dxdiag.txt file
  • DCS.log file, had to rar it because uploader wouldn't take it due to 500kb limit

System 1:

2080ti / 32gb ram / 9900k

 

System 2 :

1080 / 16gb ram / 7700k

Syria Dynamic Sandbox v.10b.miz

DxDiag.txt

dcs-log.rar

Edited by Stal2k
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  • ED Team

Hi

 

I am unable to reproduce on my system.

 

For testing purposes please remove all unofficial mods.

 

C:\Users\stal2\Saved Games\DCS.openbeta\Mods

 

run a full cleanup and repair https://www.digitalcombatsimulator.com/en/support/faq/repair/

 

Do you always run the second mirror? if so disable it and only use the dcs mirror.

 

let us know if it helps

 

https://www.digitalcombatsimulator.com/en/support/faq/repair/

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This did happen to me before but it's inconsistent. It happened when I was fairly deep into a campaign mission in Ka-50 and kept flipping in and out of F10 map, measuring, zooming in and out, turning on labels in F10 map, Ctrl+F11 to get closer look at the target... Target was obscured by something and I wanted to see what it was. Then same type of crash. Happened to me twice and I just limited F10 map usage.

 

Didn't try to replicate or troubleshoot it because as I said, happens to me only when fairly deep into a mission.

 

Vive Pro.

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Hi

 

I am unable to reproduce on my system.

 

For testing purposes please remove all unofficial mods.

 

C:\Users\stal2\Saved Games\DCS.openbeta\Mods

 

run a full cleanup and repair https://www.digitalcombatsimulator.com/en/support/faq/repair/

 

Do you always run the second mirror? if so disable it and only use the dcs mirror.

 

let us know if it helps

 

https://www.digitalcombatsimulator.com/en/support/faq/repair/

 

BIGNEWY, I know its a bit of a wall of text but you can see I've tried these things under the "Things I've tried section." It happens on two different computers with effectively independent hardware.

 

When I was trying to get it to stop previously I've removed all mods. I'm happy to do it again and video if that is the only way to get someone to look into this. Clearly, from this thread and the others I linked it's not just me.

 

As far as running a 2nd VR mirror goes, no I do not, I simply did that for the recording to let illustrate what was going on in the HMD vs the desktop where you can actually see the crash.

 

To everyone else, yes it's very inconsistent for me as well and I've gotten decent at "playing around" the issue in terms of not doing things that will piss the game off. As I said, I went for roughly a two week spell where I was just running Raven One and very light missions and it never crashed. I just also figured out how to kind of force it to happen which made the video an unedited 4 minutes instead of a fairly lengthy capture just waiting for it to happen on it's own.

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This did happen to me before but it's inconsistent. It happened when I was fairly deep into a campaign mission in Ka-50 and kept flipping in and out of F10 map, measuring, zooming in and out, turning on labels in F10 map, Ctrl+F11 to get closer look at the target... Target was obscured by something and I wanted to see what it was. Then same type of crash. Happened to me twice and I just limited F10 map usage.

 

Didn't try to replicate or troubleshoot it because as I said, happens to me only when fairly deep into a mission.

 

Vive Pro.

 

This is very similar to what happens to both myself and another guy I fly with a lot. That is why I'm speculating it has to do with moving a lot of data into and out of the RAM when it is at, or very nearly full. That would make sense with spending a lot of time in a mission, the F10 map is very much a kiss of death for us (and this bug) as well.

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@Stal2K

 

Can you do another test? This time let GPU-Z running it's sensors page and have a closer look at VRAM usage. Also let SteamVR performance graph running parallel and post your settings for DCS PD setting and SteamVR SS (resolution per eye in Video and per-App setting for "DCS"). I know this problem very well from my old 2080ti running DCS at extremely high settings, when DCS tries to allocate more than 11GB VRAM. In my case i solved this by throwing a s**tload of money at the problem (RTX3090). I can switch to the F10 map in an instant now, no hanging or occasional SteamVR crash anymore, i can also switch to every module in an instant.

Edited by Alec Delorean

i9 10920X @4.8GHz, 3090 OC, 64 GB RAM @3600, Valve Index, HOTAS & Rudder: all Virpil with FFB base mod (G940)

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@Stal2K

 

Can you do another test? This time let GPU-Z running it's sensors page and have a closer look at VRAM usage. Also let SteamVR performance graph running parallel and post your settings for DCS PD setting and SteamVR SS (resolution per eye in Video and per-App setting for "DCS"). I know this problem very well from my old 2080ti running DCS at extremely high settings, when DCS tries to allocate more than 11GB VRAM. In my case i solved this by throwing a s**tload of money at the problem (RTX3090). I can switch to the F10 map in an instant now, no hanging or occasional SteamVR crash anymore, i can also switch to every module in an instant.

 

I mean sure, but what will that accomplish? That kind of lends some credence to my theory of this being memory-related. The intent of my post was to 1) illustrate this issue and 2) get them to fix it.

 

If someone on the dev team (or you are on the dev team) would benefit from doing that I'd be happy to. I'm hesitant to really get lost in the settings as then this becomes a conversation about my settings and not the issue of VR HMDs shutting down. My settings haven't really changed in ~5 months or so on my main rig and are very conservative on my 2nd system. I'm not using any in-game PD and about 150% SS total via steam.

 

My DCS settings are effectively in line with the latest VR best practice video, no MSAA, low anisotropic, low/flat shadows, low terrain texture etc. Even if they were cranked, it's not a valid reason for the game to crash like this during moments of intense memory I/O.

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+1 for this thread.. ever since the last couple Open Beta patches, this problem has been happening to me as well. about 90% of the time, if I switch to F10 from cockpit view, or switch to any other view, other than cockpit, DCS crashes SteamVR.

 

I'm glad that I'm not the only person having this issue. I also checked the Steam Discord and have seen similar posts regarding this issue recently.

 

I have an i7 9700k at 3.60GHz, 32GB ram, GeForce RTX 2080 with 8GB ram and an HP Reverb. DCS is the only sim that crashes Steam VR on my system. I can fly IL2 for hours, changing views constantly, no issues. Try to fly DCS, change to F10 one or two times, and SteamVR crashes. I have reloaded my sim rig 2 times now, making sure it is clean, and have tried researching and adjusting WMR settings, Steam VR settings, and to no avail.... can't get past this issue.

 

 

Very frustrating.....

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@Stal2k

 

Try to set your SS via steam setting to 100% and check if the problem persists, just to be sure. After that start to raise to 110% 120% ... Keep an eye on VRAM allocation. Lowering texture quality also helps with VRAM usage.

We all know DCS's core engine is pretty much unoptimized for todays hardware, it's VRAM usage is actually pretty normal for a game that was made for running on just one monitor. VR needs more VRAM because it needs to reserve more videomemory for 3 screenbuffers instead of just one (your monitor and 2 additional panels in your HMD). The higher the resolution, the more videomemory is needed for these screen buffers. Put geometry and texture load plus some effect buffers on top of it and bamm, VRAM runs out of space. DCS definitely needs better memory management, frequent purges to get rid of unused data. But they are working on it and we may have to wait for 2.7.0 or 3.0 idk.

Edited by Alec Delorean

i9 10920X @4.8GHz, 3090 OC, 64 GB RAM @3600, Valve Index, HOTAS & Rudder: all Virpil with FFB base mod (G940)

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  • ED Team

Good advice above, running steamVR at 150% will decrease performance and put a larger strain on your gpu.

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VR needs more VRAM because it needs to reserve more videomemory for 3 screenbuffers instead of just one (your monitor and 2 additional panels in your HMD).

 

The monitor is just a mirror and doesn't take any VRAM or frame buffer. I understand the point you're trying to make however but I do not believe this is related to VRAM as everyone reporting this issue encountered this while using F10 map.

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Your monitor is still running all the time, displaying windows GUI and the VR mirror. It always uses some VRAM or it wouldn't be able to display anything. Another trick may be lowering desktop resolution during VR sessions, might free some extra videomemory. Atm, i'm just looking at my browser and VRAM shows 1.4GB of usage (ultrawide monitor running 3840x1600).

I also had the problem with switching F10 to map/F-14 on carrier running very high SS, it's gone now because now i have 24GB VRAM.

Edited by Alec Delorean

i9 10920X @4.8GHz, 3090 OC, 64 GB RAM @3600, Valve Index, HOTAS & Rudder: all Virpil with FFB base mod (G940)

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Your monitor is still running, displaying windows GUI and the VR mirror. It always uses some VRAM or it wouldn't be able to display anything. Another trick may be lowering desktop resolution during VR sessions, might free some extra videomemory. Atm, i'm just looking at my browser and VRAM shows 1.4GB of usage.

I also had the problem with switching F10 to map/F-14 on carrier, it's gone now because now i have 24GB VRAM.

 

Windows by itself without monitor will use about 950MB of VRAM. There's nothing we can do about that. And having the monitor on uses about 250MB. Mirror literally takes no extra VRAM. So turning off monitor will save you about 250MB if you're desperate. But it's not like a 3rd screen the game has to render.

Edited by Taz1004
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The amount of VRAM allocated for screen buffers is connected to the resolution you are running for each screen, in my case it's 1.4GB just for one screen at 3840x1600. Monitor on or off doesn't count as long it is connected to your video card. If i had my 2080ti still installed it would mean only 9.6GB VRAM left for any other activity. Goodness... What are you running, looks like 1920x1080 on your monitor?

Edited by Alec Delorean

i9 10920X @4.8GHz, 3090 OC, 64 GB RAM @3600, Valve Index, HOTAS & Rudder: all Virpil with FFB base mod (G940)

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The amount of VRAM allocated for screen buffers is connected to the resolution you are running for each screen, in my case it's 1.4GB just for one screen at 3840x1600. Monitor on or off doesn't count as long it is connected to your video card. If i had my 2080ti still installed it would mean only 9.6GB VRAM left for any other activity. Goodness... What are you running, looks like 1920x1080 on your monitor?

 

3440x1440. Disconnecting the monitor has same effect as turning it off.

 

All I'm trying to say is that VR mirror doesn't cost any extra resources. Many people tend to believe it does. It does not. It's only filling in the pixels that's already been drawn. It's same as setting your game resolution to 720P, and then blowing it up to 4K. Your system is only calculating for 720P and doesn't take any resources filling the pixels of 4K display.

 

Leaving monitor on is essential part of gaming. If I have to turn it off or disconnect it or lower its resolution to prevent crash, then something is wrong with the game design. Is my point.

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  • ED Team

I will have another tester check, but at this time I am unable to reproduce on my system.

 

thanks

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The monitor is just a mirror and doesn't take any VRAM or frame buffer.

 

Are we talking about the same thing here? I'm talking about your hardware display monitor made of plastic, some aluminium, PCBs and screen panel - running windows gui and certain open windows like SteamVR UI, DCS VR mirror etc.

This already allocates a certain amount of VRAM, are we on the same page now?

Edited by Alec Delorean

i9 10920X @4.8GHz, 3090 OC, 64 GB RAM @3600, Valve Index, HOTAS & Rudder: all Virpil with FFB base mod (G940)

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Are we talking about the same thing here? I'm talking about your hardware monitor running windows gui and certain open windows like SteamVR UI, DCS VR mirror etc.

This already allocates a certain amount of VRAM, are we on the same page now?

 

Maybe you misunderstood me. The part of your comment I first quoted.

 

VR needs more VRAM because it needs to reserve more videomemory for 3 screenbuffers instead of just one (your monitor and 2 additional panels in your HMD).

 

VR needs more VRAM is correct. But not 3 screenbuffers.

 

The additional windows you're talking about, SteamVR UI, and DCS VR Mirror is something you can't turn off. And doesn't take any VRAM.

 

Hardware monitor, I'm sure he had it running for recording the bug.

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Hmm, i just closed my browser left GPU-Z running, VRAM usage goes down to 1.2 GB. Fired the browser up again and additionally opened Thunderbird, VRAM shoots up to 1.8 GB. Isn't that strange?

i9 10920X @4.8GHz, 3090 OC, 64 GB RAM @3600, Valve Index, HOTAS & Rudder: all Virpil with FFB base mod (G940)

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Hmm, i just closed my browser left GPU-Z running, VRAM usage goes down to 1.2 GB. Fired the browser up again and additionally opened Thunderbird, VRAM shoots up to 1.8 GB. Isn't that strange?

 

No, that's very obvious. Are you comparing SteamVR UI to Thunderbird?

 

If you want to test how VR Mirror works, connect another display to your graphic card. Set it to mirror. Not extend. See if it uses any extra resources at all.

Edited by Taz1004
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Edit: Ok, found the time to get deeper into this. VR renders 2 cameras at a given resolution (DCS's integrated openVR or oculus api looks for the installed Headset driver/compositor, sets it's default resolution for each panel), DCS's internal PD value gives the option of a render resolution multiplicator per eye (1.0 recommended for all HMD's except Oculus's api, here the PD value hooks directly into the PD value of it's api). A rendered finished frame per eye is handed over by DCS to the VR compositor (Steam VR for example). The compositor handles another render resolution pass per eye and sends it to each of your display panels in your HMD (Steam VR SS setting). If you have a VR HMD connected to your GPU, it's technically like having 2 additional monitors connected, therefore the GPU needs to allocate extra separate screenbuffers, one for the left eye, one for the right eye. Every pixel needs to be drawn and saved somewhere, this is what screenbuffers are allocated for. The VR mirror on your desktop however, can be just a copy of the left or the right eye, or an extra camera centered between each eyes. I can't tell which way DCS is going here. However, the VR mirror on the desktop needs to draw an additonal window on your desktop, this window is filled with extra pixels that get copied(!) from one of the VR screenbuffers to the screenbuffer of your monitor and adds usage of VRAM for the screenbuffer of your monitor which is displaying the VR mirror (not that much, the mirror is mostly a fraction of HMD panel resolution, but still something). This is basic windows api stuff.

 

The higher the resolution you set per PD value ingame and/or SteamVR SS the more VRAM needs to be allocated to be able to render each eye's frame to the panels in your HMD.

 

Have a nice day.

Edited by Alec Delorean

i9 10920X @4.8GHz, 3090 OC, 64 GB RAM @3600, Valve Index, HOTAS & Rudder: all Virpil with FFB base mod (G940)

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@Stal2k

 

Try to set your SS via steam setting to 100% and check if the problem persists, just to be sure. After that start to raise to 110% 120% ... Keep an eye on VRAM allocation. Lowering texture quality also helps with VRAM usage.

We all know DCS's core engine is pretty much unoptimized for todays hardware, it's VRAM usage is actually pretty normal for a game that was made for running on just one monitor. VR needs more VRAM because it needs to reserve more videomemory for 3 screenbuffers instead of just one (your monitor and 2 additional panels in your HMD). The higher the resolution, the more videomemory is needed for these screen buffers. Put geometry and texture load plus some effect buffers on top of it and bamm, VRAM runs out of space. DCS definitely needs better memory management, frequent purges to get rid of unused data. But they are working on it and we may have to wait for 2.7.0 or 3.0 idk.

 

Listen, I know you are trying to help but the issue is not the DCS doesn't run well, or that SS taxes hardware. Those things were true 3 patches ago and you could still play this game without getting booted to the desktop from a random SteamVR fail that was introduced in a semi-recent OB build.

 

Everything you said is true with regards to the memory management and whatnot, but at no point is crashing the VR overlay part of what we've kind of collectively accepted as 'unoptimized.'There was a change to the way the F10 menu was handeling things a few patches back and my intent is to highlight that there might be some lingering issues impacting VR users that are really frustrating.

 

FWIW I can also do this without ANY SS on my other system, and yes I think between the myriad of other people reporting the issue and the feedback in this thread we can all at least sort of agree it's centered around 1) a recent OB patch 2) memory usage 3) the F10 menu.

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Good advice above, running steamVR at 150% will decrease performance and put a larger strain on your gpu.

 

Thanks BN, yes I agree but as I'm sure you're aware most folks with 20xx gpus are heavily CPU bound. My GPU usage is typically around 60%, in fact upgrading to the 2080ti required MORE SS just to slow down the GPU enough to be able to dance comfortably with the CPU frame times.

 

This is what I was trying to avoid in making this about my settings, I would totally understand if I was the only person having this problem - but I'm not and as more and more people are replying you can see the commonalities (timing, and F10 usage/memory stressing)

 

I will have another tester check, but at this time I am unable to reproduce on my system.

 

thanks

 

Thank you, that is really the only goal here is to get some attention put onto the issue. If they are unable to reproduce I'm happy to try to find out exactly which OB introduced the issue, obviously I'd rather not spend the time if you guys can do it internally but it's been really hurting the experience lately.

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