AH-64 massive stutters in VR South Atlantic Map

[Ramires]

Hi folks,

I'm struggling with the VR-Performance on South Atlantic Map. It only occurs in the Apache (have already made attempts with othter A/C like the F-16, AV-8, UH-1). Stutters only occur during hover or low level flight and are increasing when looking to the left or right. At a certain altitude stuttering ends... any ideas?

Thanks! 

 

Specs: GTX 3080, Rift S Ryzen i5

[BIGNEWY]

Hi, 

please let us know your DCS settings and attach a track replay showing the issues. 

thanks

[TZeer]

I have seen the same behaviour in Caucasus and Nevada. Smooth as butter looking straight ahead (Motion Reprojection activated), turning my head to left or right, and gradually the stutter gets more and more visible.

I will see if I get some time today to make a post with performance metrics etc from the GPU/CPU-load, combined with the observed behaviour. I seem to remember that when this happened I also observed changes in the GPU/CPU workload.

Edited August 3, 2022 by TZeer

[TZeer]

@BIGNEWY

Ok, so did just a quick test in 2d mode, as it's visible there as well.

I did the test in Nevada, in the very west lower part, where there is not much going on. This to keep terrain details to a minimum. Anyway, this is visible on all maps.
Fist picture is inside the cockpit. Doing above 200 FPS, looking straight ahead.

Next pictures are to the 90 degrees left and right in the cockpit.

When taking the pictures they drop to 130 FPS, but while in flight the reduction was roughly 20 FPS, 180 FPS. But for some reason the massive FPS drop while taking a screenshot, only happens when looking to the sides. Not towards front. There the FPS keeps at 200+ FPS.

This is on a overclocked AMD 6900XT card, and we can argue that the FPS drop is a non issue since we are still running 180 FPS. But when we are getting into lower tier cards and VR space, this drop gets very noticable.

Putting up the video feed from the TADS, my FPS dropped to 150 FPS, now I had no difference when looking to the sides. And I got same behavior when taking screenshots. All 3 instances dropped the FPS to roughly 95-100 FPS.

Question is, what is making the FPS drop when looking out of the cockpit to the sides?

 

Edited August 4, 2022 by TZeer

[BIGNEWY]

3 minutes ago, TZeer said:

@BIGNEWY

Ok, so did just a quick test in 2d mode, as it's visible there as well.

I did the test in Nevada, in the very west lower part, where there is not much going on. This to keep terrain details to a minimum. Anyway, this is visible on all maps.
Fist picture is inside the cockpit. Doing above 200 FPS, looking straight ahead.

Next pictures are to the 90 degrees left and right in the cockpit.

When taking the pictures they drop to 130 FPS, but while in flight the reduction was roughly 20 FPS, 180 FPS. But for some reason the massive FPS drop while taking a screenshot, only happens when looking to the sides. Not towards front. There the FPS keeps at 200+ FPS.

This is on a overclocked AMD 6900XT card, and we can argue that the FPS drop is a non issue since we are still running 180 FPS. But when we are getting into lower tier cards and VR space, this drop gets very noticable.

Putting up the video feed from the TADS, my FPS dropped to 150 FPS, now I had no difference when looking to the sides. And I got same behavior when taking screenshots. All 3 instances dropped the FPS to roughly 95-100 FPS.

Question is, what is making the FPS drop when looking out of the cockpit to the sides?

 

 

Please attach a track replay showing what you have seen so I can compare on my system. 

Now dont get me wrong, you are obviously seeing some drops, but the frames you are getting are awesome, many people on lower end machines are happy with 45fps. 

[TZeer]

@BIGNEWY will do it later 

I know, awesome frames, and quite lucky.

But as I mentioned, with lower tier cards and in VR, drops like this is the difference between a fluid gameplay and stutter. I normally fly in VR, and the performance drops when looking out to the sides are very noticable.

This kinds of issues are also not always very easy to find. As they don't usually come to light until you have enough overhead performance available.

[Hiob]

Test the following please:

go in the graphics.lua in the main installation folder /config folder.

Around line 420 somewhere is an entry like this "maxfps = 180". Change that to 300 and see if the issue goes away. No worries, you can't damage anything. Make a copy if you are unsure.

DCS acts weird with very high fps - mostly the fps drops low and fluctuate a lot. Has worked for multiple people multiple times by now.

(My assumption is, that the algorithm that is supposed to restrict excessive fps is flawed)

Edited August 4, 2022 by Hiob

[BIGNEWY]

33 minutes ago, Hiob said:

Test the following please:

go in the graphics.lua in the main installation folder /config folder.

Around line 420 somewhere is an entry like this "maxfps = 180". Change that to 300 and see if the issue goes away. No worries, you can't damage anything. Make a copy if you are unsure.

DCS acts weird with very high fps - mostly the fps drops low and fluctuate a lot. Has worked for multiple people multiple times by now.

(My assumption is, that the algorithm that is supposed to restrict excessive fps is flawed)

 

you should not mess with config files in game. 

it is better to set a desired FPS target in your autoexec.cfg in saved games DCS config folder 

options.graphics.maxfps = 300

 

I have mine set to 90 personally 

[Hiob]

Hi @BIGNEWY,

you are certainly right. I had problems with autoexec.cfg in the past and therefore went with the direct approach. I don't suggest altering the graphics.lua as a permanent solution (which it isn't anyway, because every update or repair of the game will restore the original file anyway), but as a quick and simple test if the problem lays inthere. I admit freely, that I never tested if it worked with the autoexec as well, but it definitely solved some very-high-fps related problems in the past.

Edit: My personal solution to this "quirk" is to stay away from 180 fps in the first place by ramping up the visual fidelity....

Edited August 4, 2022 by Hiob

[TZeer]

20 minutes ago, Hiob said:

Test the following please:

go in the graphics.lua in the main installation folder /config folder.

Around line 420 somewhere is an entry like this "maxfps = 180". Change that to 300 and see if the issue goes away. No worries, you can't damage anything. Make a copy if you are unsure.

DCS acts weird with very high fps - mostly the fps drops low and fluctuate a lot. Has worked for multiple people multiple times by now.

(My assumption is, that the algorithm that is supposed to restrict excessive fps is flawed)

 

This line is at maxfps=500. So that's not the issue. Doing the same thing in the Huey gives me close to 300 FPS. I had a post in a different part of the forums where this was the issue. And you came to the rescue with the solution .

A while back ago I was able to get the Apache to run @45 FPS locked in Rivatuner with motion reprojection off in OpenXR, with a Reverb G2 @ 90Hz. The flight was buttersmooth. Cockpit was crystal clear, and no artefacts due to MR. Only had some ghosting on objects when looking to the sides. But the smooth framerates was well worth it.
I went to work for 2 weeks, came back, updated DCS, and have never been able to get the same results again.

Anyway. Problem here is that people who usually fly in 2d and run FPS locked at 60FPS or whatever. Or having G-sync monitors never notices if their FPS goes from 100 to 80 FPS.

But when you are running VR, or are already on the limits of decent perfromance, this kinds of issues gets very obvious.

[TZeer]

Here is a screnshot of my settings and a small track.

So I get a reduction every time I move my view left or right. Zooming out or in seems to make it go away. It's not much more than -20 FPS maybe. So 10% hit relative to my 200 FPS looking straight in the cockpit.

Since I normally fly in VR I don't use MSAA, as it sucks to much performance. But I had a test where I added 4xMSAA while in 2d mode. Now I suddenly have an INCREASE of FPS when looking left or right. It's not much, maybe 10 FPS.

I will do some testing in VR, and see If I get some usefull data from it.

 

Edit:
Was unable to get anything decent. Think my memory got maxed out. Was getting about 75 FPS average with a 99% utilization on my GPU and 14% headroom on my CPU. But suddenly my FPS went down to 60 FPS, while the GPU utilization went down to 70% and CPU headroom went up to 25%....
My videomemory was maxed out @ 16gb 

cockpit_fps_test.trk

Edited August 4, 2022 by TZeer

[BIGNEWY]

31 minutes ago, TZeer said:

Here is a screnshot of my settings and a small track.

So I get a reduction every time I move my view left or right. Zooming out or in seems to make it go away. It's not much more than -20 FPS maybe. So 10% hit relative to my 200 FPS looking straight in the cockpit.

Since I normally fly in VR I don't use MSAA, as it sucks to much performance. But I had a test where I added 4xMSAA while in 2d mode. Now I suddenly have an INCREASE of FPS when looking left or right. It's not much, maybe 10 FPS.

I will do some testing in VR, and see If I get some usefull data from it.

cockpit_fps_test.trk 948.42 kB · 1 download

 

I have my fps capped at 90 and these are my results, obviously I have a strong PC, but I am not seeing any fluctuations  

[TZeer]

4 hours ago, BIGNEWY said:

I have my fps capped at 90 and these are my results, obviously I have a strong PC, but I am not seeing any fluctuations  

If you have capped your FPS @ 90 you will not see anything. As you have plenty of extra resources to spare.

I tried to cap @ 90 FPS, but due to the FPS bug, where powerful cards as the 3080, 3090 and 6900XT get weird behaviour, my FPS dropped to 60-70 FPS. I need to have minimum FPS in the autoexec.cfg at minimum 190 FPS, if not, my FPS goes down to 60-70 FPS with my current settings.

I tried using MSI afterburner to see if I could get some data from it. But nothing useful. Only thing I was able to see was as the FPS went down, my average frametime went from around 6 ms, to 7ms. And the framebuffer went down....
It might be something CPU bound. Since when I increased MSAA to 4x, I could no longer see the framedrop.

This might also explain why it's more of an issue in VR than in 2d. As CPU time is much more imponrtant there.

Edited August 4, 2022 by TZeer

[BIGNEWY]

if you have NVIDIA you can set the frame rate target in the NVIDIA control panel, which is what I do, 90 fps is more than enough for a great experience. 

[TZeer]

I would have if I flew in 2d 

But I fly in VR 

As of now, I only think this is an issue for us VR users chasing every millisecond in frametimes to increase performance in the Apache.

Edited August 5, 2022 by TZeer