VR stuttering - less cores, less stuttering (to a point)

[NeinNineNiner]

Hey all,

I noticed a glitch in the DCS 2.9 multithreading.  I'm running an i9 11900K with 64GB and a 3090 FTW GPU.

I ran two tests, both in an A10 in Syria using the Takeoff instant action.

• Test 1 - With all 16 (logical) cores enabled, my stuttering in VR was outrageous.  Every 0.5 to 1 sec, a big stutter.
• Test 2 - Process Lasso'd DCS to use cores 11 - 15.  Far, far fewer stutters (but they're still present every once in awhile, especially when all the cores get fully loaded, then back to heavy stuttering)

My dcs.log is attached.  My CPU doesn't have P/E cores on the die.  Just hyperthreading.  FPS are always very high (pegged out at 72 fps, solid).  The only thing I can conclude, at this point, is that there is a glitch with the way multithreading coordinates resources between threads.  More cores should not result in more stuttering.

Other things I've tried (to no avail):

• debar on/off
• hyperthreading on/off
• un-parking cores

dcs.log

[Mr_sukebe]

Interesting test, thanks for posting.

My own experiences suggest that DCS appears to be primarily use 4 cores.  My assumption is that ED configured MT to work with lower spec CPUs aswell as 8 core units.  
 

I wonder if CPU core usage is conducted by the application or Windows?  Have to say that I don’t know, though I’m guessing it’s windows.

ref the stutters, no idea why that would be.  Is it windows switching the used cores and possibly resulting in a time delay??

[Dangerzone]

13 hours ago, NeinNineNiner said:

Hey all,

I noticed a glitch in the DCS 2.9 multithreading.  I'm running an i9 11900K with 64GB and a 3090 FTW GPU.

I ran two tests, both in an A10 in Syria using the Takeoff instant action.

• Test 1 - With all 16 (logical) cores enabled, my stuttering in VR was outrageous.  Every 0.5 to 1 sec, a big stutter.
• Test 2 - Process Lasso'd DCS to use cores 11 - 15.  Far, far fewer stutters (but they're still present every once in awhile, especially when all the cores get fully loaded, then back to heavy stuttering)

My dcs.log is attached.  My CPU doesn't have P/E cores on the die.  Just hyperthreading.  FPS are always very high (pegged out at 72 fps, solid).  The only thing I can conclude, at this point, is that there is a glitch with the way multithreading coordinates resources between threads.  More cores should not result in more stuttering.

Other things I've tried (to no avail):

• debar on/off
• hyperthreading on/off
• un-parking cores

dcs.log 155.42 kB · 4 downloads

Out of curiosity - when you're at the main DCS screen, if you bring up the FPS does it show locked? If you then move the mouse around, does the FPS become unstable? 

[NeinNineNiner]

4 hours ago, Dangerzone said:

Out of curiosity - when you're at the main DCS screen, if you bring up the FPS does it show locked? If you then move the mouse around, does the FPS become unstable? 

Moving the mouse around doesn't change the FPS on my rig.  I use a plain old $10 wireless mouse so the polling doesn't appear to be an issue.

5 hours ago, Mr_sukebe said:

Interesting test, thanks for posting.

My own experiences suggest that DCS appears to be primarily use 4 cores.  My assumption is that ED configured MT to work with lower spec CPUs aswell as 8 core units.  
 

I wonder if CPU core usage is conducted by the application or Windows?  Have to say that I don’t know, though I’m guessing it’s windows.

ref the stutters, no idea why that would be.  Is it windows switching the used cores and possibly resulting in a time delay??

You might be right about the number of cores, but the funny thing is that 5-6 seems to be the sweet spot for me.

My hunch is that this is probably processor specific.  I'll wager that folks with 12th and 13th gen chips don't have this issue once they un-park and disable E-cores.

[Dangerzone]

7 hours ago, NeinNineNiner said:

Moving the mouse around doesn't change the FPS on my rig.  I use a plain old $10 wireless mouse so the polling doesn't appear to be an issue.

Good to know. I have the issue, even though my mouse is a standard 'poor mans' mouse too that only polls at 125hz, but still seems to interrupt the FPS. I've found locking the FPS at 72 using Rivatuner stops this from happening in the main menu, but I think it's only masking/hiding a deeper issue. If you're using any sort of FPS limiter (whether in DCS, NVIDIA Cpanel, etc) - it might be worth removing the limit while diagnosing just incase it's masking issues.

As for your wager, I'll take that bet. I have a 13900KF with 4090 and 64GB of RAM and a poor mans mouse - and I'm having stuttering issues too that I have to constantly fight, so it's a sure bet for me. 

I've been playing around with limiting different cores in Process Lasso (using SETS and not just affinity to reserve those cores solely for DCS) but still haven't found a solution yet.

[skywalker22]

I have 9800X3D, 4090 and I also experience lots of stuttering here and there, it occurs just randomly, couldn't find the pattern yet. It stutters for lets say 30 seconds, then it stops, and it stutter again on 10minutes, and lasts another 30seconds. 

[Dangerzone]

46 minutes ago, skywalker22 said:

I have 9800X3D, 4090 and I also experience lots of stuttering here and there, it occurs just randomly, couldn't find the pattern yet. It stutters for lets say 30 seconds, then it stops, and it stutter again on 10minutes, and lasts another 30seconds. 

That one could be your preload radius, or it loading in additional map. For instance - if you spawn in a helicopter, and then rotate the helicopter, you may notice it stuttering when you turn 180 degrees. (I don't know, but i think it might be loading more textures in the direction you face). Then keep rotating back and forth a little, and you may find it dies down.

Likewise if you're flying in a direction, it could be periodically loading more parts of the map. If it is the preload - you could try reducing the preload radius to see if this helps.

[NeinNineNiner]

What's so strange about this issue is that (I'm guessing), for all of us, we have solid high FPS.  That's one thing I'm impressed with DCS for .. beautiful graphics and good FPS.  But damn these stutters make VR difficult to use.  Have any of you guys tried reverting to the single threaded DCS version and seeing if that improves things?

[Dangerzone]

1 hour ago, NeinNineNiner said:

What's so strange about this issue is that (I'm guessing), for all of us, we have solid high FPS.  That's one thing I'm impressed with DCS for .. beautiful graphics and good FPS.  But damn these stutters make VR difficult to use.  Have any of you guys tried reverting to the single threaded DCS version and seeing if that improves things?

There is no single threaded version anymore. Unless you downloaded a year old(?) install which really is impractical for me as I enjoy the MP cooperative side of DCS. 
 

Bit you are right, these stutters make VR difficult to use. I’m definitely flying less these days, hoping that these issues may one day actually be acknowledged by ED, and they might throw us a bone. At the moment, I get the feeling they don’t believe it’s a DCS issue and we’re on our own trying to find workarounds. 

But given nothing is consistent and YMMV is very much a thing, unless ED find a fundamental flaw with their multithreading, the average dev and support people would be as much out of their depth as we are. Especially given there’s so much different hardware combinations out there that seem to be affected differently. 

Edited Wednesday at 03:08 AM by Dangerzone

[Qcumber]

The only time I get stutters is when my fps drops below headset refresh rate, which is expected, or the CPU/GPU frametime pushes close to 13.8 ms. I have no limit on cores and most of the time get fairly balanced use across all cores. 

[skywalker22]

8 hours ago, Dangerzone said:

That one could be your preload radius, or it loading in additional map.

I only had set to 65k (based on someone's instructions). But would it stutter as soon as I get into the cockpit and starting up the aircraft, while staning still on the same spot for like 4minutes? Hard to say its preload radius issue.

--

Isn't this it? It was in updates log from few days ago, ED stated they fixed it. But apparently not.

--

And its not just after joining the server, also when flying, but maybe the stuttering doesn't last that long as for the 1st time when joining the server.

Edited Wednesday at 07:43 AM by skywalker22

[LOW_Hitman]

I also saw some performance issues in dcs-vr before the last 2 patches came out. A few months ago i enabled HAGS again (hardware accelerated gpu scheduling) on my system. Yesterday i disabled this setting to se if it still causes issues and it solved the stutter issue for me.

So HAGS - off gave me a way better overall performance in dcs-vr.

Maybe something that could help.

 

[Shades71]

Not sure if this is related but have you checked whether you are being throttled in anyway?

I happened to have intel XTU open when i was in a multiplayer session and experiencing stutters and i noticed the current/EDP limit throttling was maxing out and also my cpu temp was up to 86 deg. Digging a bit deeper i installed HWinfo which told me i was being throttled 45% of the time.

I ended up under-volting my cpu and dropping the boost clock from x46 to x45 - stutters were pretty much eradicated.

I was also running open xr tools, mainly for the turbo mode, which had boosted my performance in the past. Now, I discovered, it was holding me back. I reset to defaults and disabled it, this allowed me to push Virtual desktop from high to ultra at a solid 72hz.

I get the odd stutter every now and again but i believe this is a network issue as i'm connected to US servers from AU.

I'm running an i5-11600k, 48gb ram, RTX 4070TI

[WipeUout]

Some possible problems:

1. Windows 11 23Hxx.  Swtiching to 24H2 could improve quite a bit as it is more stable for both AMD and Intel.

2. HAGS on.  Since a couple of updates, I started to get stutters and had to disable HAGS, not sure if it is nvidia driver related or windows related but no stutters anymore.

3. Process Lasso.  Good tool to ensure DCS gets priority on performance cores for Intel mainly, I find little to no benefit on my 9800x3D compared to my previous 13900k.

4. Overclocking your GPU.  In some cases, this can cause stutters even with very light overclocking.  Try disabling it if applicable to see if it makes a difference.

5. Caping FPS in DCS.  If you cap your FPS at the HMD refresh rate, it could cause stuttering.  Try caping 5 fps above your HMD refresh rate, i.e. 95 FPS for a 90hz refresh rate.

Edited yesterday at 12:37 AM by WipeUout
Typo

[LOW_Hitman]

vor 15 Stunden schrieb WipeUout:

Some possible problems:

1. Windows 11 23Hxx.  Swtiching to 24H2 could improve quite a bit as it is more stable for both AMD and Intel.

2. HAGS on.  Since a couple of updates, I started to get stutters and had to disable HAGS, not sure if it is nvidia driver related or windows related but no stutters anymore.

3. Process Lasso.  Good tool to ensure DCS gets priority on performance cores for Intel mainly, I find little to no benefit on my 9800x3D compared to my previous 13900k.

4. Overclocking your GPU.  In some cases, this can cause stutters even with very light overclocking.  Try disabling it if applicable to see if it makes a difference.

5. Caping FPS in DCS.  If you cap your FPS at the HMD refresh rate, it could cause stuttering.  Try caping 5 fps above your HMD refresh rate, i.e. 95 FPS for a 90hz refresh rate.

is there any benefit when capping the fps instead of put the slider to 300 within dcs?

[Dangerzone]

6 hours ago, LOW_Hitman said:

is there any benefit when capping the fps instead of put the slider to 300 within dcs?

There can be - but people seem to have differing opinions.

I've tried both DCS limiter, and NVIDIA limiter. I've found the best one to use (if limiting) is actually RivaTuner instead. It allows for more precise limiting than DCS (plus you can change it without having to pause the game) to see the effects. 

I think a big no-no is using more than one at the same time. 

For myself - I have noticed that I get smoother FPS by limiting using RivaTuner to the same Hz as my headset. I'm still getting stuttering on the latest DCS version though - but if I limit below 72hz to around 68 - the stuttering goes away. Unfortunately 68 though on a 72hz headset is not real nice.

But in the end - you're going to get different answers from different people as some find limiting works better, others find it gives more problems. The only real way is to try it yourself.