RealDCSpilot

@FoxTwo Yes, DCS needs a better memory management algorithm. Something to clean up unneeded resources fast and effective. Then, lesser hardware specs would be enough for the same result.

On my end it affects everything, a good ingame situation for calibrating IPD is standing on the catapult of the super carrier in a F-18 or F-14 and watch the deckcrew running around your plane. If they look like children or giant NBA players, your IPD is off.

It's not "equal", if you use ingame PD you force DCS to render a higher resolution frame on it's main CPU thread. We all know that this is DCS's weak spot for a long time. By shifting the SS workload to the VR compositor, which is running as a separate process on a separate CPU core and thread plus it's own separate GPU pass, you reach a much better balance for performance on your system. It's a neat workaround for VR and the CPU bottleneck DCS is creating with the current state of it's engine.

The VR compositor needs a higher resolution frame to process predistortion for each lens. This picture explains it really well:

To bring everything together, these are the highend settings for the game (only difference is that i use "extreme" for visibility range now): and this is VRAM usage profiling for these settings on Syria map and TTI MP mission: The 3090 doesn't struggle at any point, giving a nice highend VR experience. Only CPU frametime is left as a limiting factor for FPS.

The 3090 turned DCS in a highend VR experience on my end. VRAM problems gone and everything crystal clear on double panel resolution SS plus 4x MSAA. The last limiting factor is DCS's bad CPU frametime, i hope to see improvements there in the future, after the engine overhaul.

Make sure your IPD setting is right. I have to use the ingame setting to bring everything to a realistic scale. Without everything was too small.

Yep, the needed data swapping for shared video memory on disk and RAM is more of an emergency state than normal operation. Pretty bad for performance.

@eatthis Just make a simple test and you will see. 1. set ingame PD to 1.5 and SteamVR to 100% resolution. Watch your CPU and GPU frametimes in the performance graph. Have taskmanager open to also show GPU usage. Make a screenshot. 2. set ingame PD to 1.0 and Steam VR to 150%. Again, watch your CPU + GPU frametimes and GPU usage. Make another screenshot. The results should be different, please post both screenshots here. Make sure to restart the game each time to apply the changed settings correctly.

If you mean the PD setting in DCS, it's totally different from SS (aka render resolution setting in Steam VR). The PD setting is a multiplicator that takes your standard HMD panel resolution and adds or subtracts the amount of real rendered pixels (going higher or lower than 1.0). At 1.0 your HMD will always receive the "perfect" fit for their specific amount of needed pixels for the panels, because the game is hooked directly into the VR compositor driver of your HMD. It's like the native resolution setting for a monitor display. Going higher on the PD setting will start to waste rendered pixels because the panels aren't able to display them 1:1 anyway. This will also cost valuable CPU frametime. The external render resolution setting in Steam VR for instance acts as a basic supersampling antialiasing filter. https://en.wikipedia.org/wiki/Supersampling It takes the resolution it gets from DCS and starts to oversample or undersample, depends how you set it up. It's a much more effective way to enhance image sharpness, costs only a bit more GPU ressources instead of putting more strain onto your CPU. If you see low GPU usage while running DCS, the Steam VR resolution setting should be the first setting to play with to make use of your GPU's processing headroom. It doesn't work in realtime, you always have to restart the game to see an effect. Always have an eye on VRAM usage when playing with higher SS settings.

Here is some data from real VRAM usage on my system: https://forums.eagle.ru/showpost.php?p=4522981&postcount=53

@Stal2k Okay, found out how to show real VRAM usage per process in Afterburner. As you can see VRAM usage is way too high for 11GB cards at very high VR settings (ingame and SteamVR SS). Switching to F10 map costs more than 1 GB extra. If you want to examine what is happening on your end:

Yep, keep in mind that a big fat GPU also needs a CPU with big shovels to keep up with the GPU's data amount and bandwidth at high resolutions. If the CPU gets overwhelmed, a "simple" GPU upgrade might make things worse.

@Stal2k For science, did you also tried to test Steam VR against the latest Steam VR beta? There maybe differences. (I'm on Steam VR beta since 2016)

It makes the module even worse if it's working randomly different on anyone's pc.

Looks fantastic!

@Stal2k Five pages later and you still misunderstanding what i'm trying to say. I'm not backing up ED and i'm definitely not trying to say it's your fault. You know how they work, we are the last line of beta testers. How about that, please try my suggested steps which may lead to a more precise bug report. Something like "Increased VRAM usage leads to Steam VR fail since the latest patches". Be very conservative with the first step, go pretty low on settings. Watch VRAM usage. Then go higher and try to find the sweetspot. After that, post the settings that worked before and where you are now. I can't do this anymore by myself. I can be totally wrong, it's just my theory from what i've seen on my end. It will help a lot of people to understand whats going on.

There is no extra arcade mode for the Gazelle (other modules support this mode while having separate control sets for it in the control options were you choose for instance "Ka-50" or "Ka-50 real"). The current FM is very arcade mode, yes. What doesn't make sense to me is how "Easier Controls" are much less forgiving. I'm sure you meant the opposite?

There is a high chance for triggering desorientation and motion sickness i guess.

@CobaltUK I'm only pointing at VRAM usage, DCS seems to need to allocate more ressources since the introduction of the syria map and the latest patches seem to add even more VRAM usage on top of it. I also had the same problem before with my old 2080ti. To test this on your end you can simply lower every setting that needs plenty of VRAM (render resolution with PD setting, visibility range, low textures, lower or 100% SS settings). If the problem still persists than the reason is something else. A friend of mine just ran into the same problem yesterday on a 1070, we just tested the unlock all liveries mod on our syria server with all modules available and his VRAM just filled up too much, FPS were going down, F10 map troubles. He had to restart the game without the mod to fix it.

That's because windows uses the pagefile also to cache video memory to RAM and HD. It's called shared GPU memory. The performance impact comes when dedicated VRAM is full and a lot of additional HD activity is needed to constantly load stuff from the cache back to VRAM. If the amount of data is small, you may not notice any impact. If it starts to need bigger chunks of data to swap, the trouble starts.

@FritzTheGerman unfortunately, the ingame PD setting does not work as intended by SteamVR and other VR compositors. It's actually working like the setting for monitor resolution in 2D mode. In a VR game the VR compositor and the connected HMD with it's driver define the standard resolution for both frames that have to be rendered (left and right eye). As an example with a Valve Index, 2016 x 2240 pixels per panel is the minimum needed to display a lens distortion corrected frame pixel perfect on each 1440 × 1600 pixels panel. If you set ingame PD 1.0, the game will deliver a 1:1 frame at 2016x2240 to the VR compositor that will do it's job with handling all the necessary steps to transform the correct distortion for your HMD. If you set a higher PD, the game will render a higher resolution frame. With 1.8 PD you will end up with 3628 x 4032 per eye in the first step, which is crazy high, takes a much bigger screen buffer in VRAM and will also cost CPU performance, because all CPU bound visual passes have to process a much higher amount of information. The next step is downsampling both 3628x4032 frames to 2016x2240 for the VR compositor, which is doing his distortion pass and if you set a higher resolution percentage will do another supersampling pass on top. A huge waste of performance. To get the most out of visuals in VR in DCS, never use the ingame PD, it will kill your frametimes on CPU and GPU instantly. Go for 1.0 and let the VR compositor handle it's SS passes afterwards. This way you can balance the CPU bound scenario, because 99% of the VR compositor workload goes directly to GPU usage. And there is plenty of headroom there with a 3090. In Steam VR you have the advantage of adding a second "per app" setting for supersampling to finetune GPU usage to the max. The formula is DCS PD x SteamVR general SS setting x Steam VR per app SS setting.

Well it's been 4 years, i really hope someone starts to care someday.

Did you read what that video is about? Or is the Gazelle module actually an Rotorway Turbo under the hood? Here is the same guy in the Gazelle, look at his inputs: Look how it looks like when it lifts off, not straight up in the air, like pulled up on a cable. It's unstable like any other helicopter as soon the skids loose ground contact. Why do we not see that in DCS?

@outlawal2 Yes, that's why you have to work on the cyclic in the real Gazelle all the time. Like this: From the outside it will look very stable, that's what some people don't get. @swatstar98 I count 7 seconds without correcting.