Stutters when Rolling Cache file is full and start's to get rolled with new data

Bug Reporting Hub Install, Performance & Graphics
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21

That is really interesting.

Regarding the sound there are two interesting aspects which my recordings have revealed … but I still do not understand if what I saw is reproducible or was a random event. “Audio stutters” could be a likely result.

The recordings are here:

Now … the interesting aspects:

  • Sound … is read from (and written to) dedicated local cache files.
    • (I still have to publish my aircraft specific recordings. There it is even more obvious.)
  • The data rate at which sound files are read … seems to be different … even for the same aircraft.
    • I am suspecting (guessing) that there is some IO scheduling inside the sim.
    • Meaning … if less data is written or read from the cache … then Sound can increase its data rate.

OK. I always need to stress that I have no idea how the code looks. But the very few event recordings that I looked at so far would make this plausible.

I like the overall idea (if that is what Asobo does). But I am still puzzled about the fairly low local IO data rates that I am seeing. Read+write is at around 4 MB/s.

But I think I will from now one keep an eye on sound related data transfers. Maybe there is a pattern.

2 Likes
22

So I’ve had a good day of flying today. Left the rolling cache at 16GB like I said, left the pre cache at low and today has been the best experience I’ve had so far. I’ve even put all my inibuilds scenery back in like Heathrow and had headroom on my vram. This definitely needs to be looked into by Asobo as this is clearly an issue that has been brought back over from the early days of 2020. Since returning the cache file size back to 16GB and making a new folder the micro stutters haven’t come back. I watched a few streamers last night and actually saw a few of them had the micro stutter issue and didn’t even notice it until I pointed it out. Hopefully if we can get enough votes in this post they may look into it.

23

I also had the crackle/static sounds constantly until I figured the rolling cache and pre cache issues out. Now they have gone since turning pre cache down to low for now. Let’s see what next weeks update brings.

3 Likes
24

Unfortunately it seems the update hasn’t done much good for me, left on the settings from before, the sound crackle is back, my RAM usage is now the highest its ever been at 96% over London, I’ve never ever seen over 80% before the update and on 2020 it was never above 55% usage! I have 32GB. I know the recommended was 64, but prior to the update it certainly wasn’t this high. Solve some issues, but make some others worse.

25

I think I’m going to get 64gb of ram and see if that helps at all. But it also seems there is a big VRAM usage issue in 2024.

1 Like
26

Just found this for settings that might help a few out with performance settings for different rigs.

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27

Has anyone compared this information vs. NVIDA optimized settings (for NVIDA hardware) vs. Microsoft/Asobo recommended settings?

28

Not fully, it didn’t seem far off when i had a quick look around an hour ago.

30

Thank you for the bug report.

We have created an internal ticket to see if our team already has this logged, and if not they will attempt to reproduce the issue and create a new bug report. This item is now marked as feedback-logged. If there is an existing bug report or one is created, we will move this thread to bug-logged.

1 Like
31

Stutters are back with a vengeance now! Doesn’t seem to matter what i do or change it is just a stuttering mess when at airports or taxiing around. Sometimes its worse than other times at the same airport. I’m tired of playing Settings Simulator now. I just want to fly.

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32

Certainly due to last patch 3: Constant stutters at majority of airports with the latest patch (1.2.7.0)

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33

Fingers crossed they have sorted this issue globally, not just at one airport.

Massive performance / CPU issues in certain locations in 1.2.7.0 - [MSFS 2024] Bug Reports / Airport & Sceneries - MSFS DevSupport

34

Do you have the same issue if you follow the OP’s steps to reproduce it?
• Yes!

Provide extra information to complete the original description of the issue:
• Oh wow the difference is huge! I was very happy with the performance flying GA, but I recently tried flying airliners in FS 2024 and it was a stuttery mess. I initially increased my cache to 64 GB because I have a lot of space. I fly in VR, RTX 4090, i9-12900K, Valve Index. I tried various graphics settings, but even on low settings the stutters would not go away. Reason is always limited by main thread, but even low LOD setting did not help. Now I deleted the cache, it got reset to 16 GB, and I also reduced pre-caching to low, and had the smoothest airliner flight to date. Of course I need to see if it degrades again, but there is definitely something bad going on with the cache. Probably never got tested with larger than default values.

If relevant, provide additional screenshots/video:
•

35

I am increasingly convinced that the main cause is:

  • The internal FS2024 data transfer between the rendering pipeline and the storage subsystem of the sim is coded as a synchronous API.

I think I provided solid evidence here …

I summarized the observations and claims presented in the post from above as follows:

  • A major performance problem is:
    • The sim always writes (dumps) the entire index area … up to 512 MB
      • … even when very large parts of the index did not change.
      • And this happens so frequently, that 50 to over 90% of all data written into the RollingCache.ccc file is useless, unchanged index area!
  • It feels reasonable to suspect, that blocking the RC file for 50 to 200 milliseconds might cause visible FPS stutter … by means of backpressure.
    • People reported in other threads that they seem to observe less FPS stutter with fresh (new) empty RC files.
      • That would be consistent with bigger and slower index area writes … due to larger RC files.

However, if the rendering pipeline and the storage subsystem get decoupled properly … as one should do in a very high performance software system like FS2024 … then abnormal backpressure (e.g. due to blocked resource like a strictly serial access to the RC file) should not cause any visual stutters.

A fragmented (“over-full”) or a very large Rolling Cache (with a very large index) is not the actual problem. It is just a condition which exposes (by visual stutters) the actual problem of a missing decoupling (e.g. via async input-output handover queues).

6 Likes
36

This all jives with what I have been experiencing, and seems less a graphics problem than a CPU issue…

So, I did some research and made adjustments to my settings, and things improved. For a while.

It seems there might be a memory leak or something similar going on. The more flights you fly after a restart, the worse it gets until you restart again; I flew three this morning with no stutter or degradation. The fourth dropped the framerate very low. The lower framerate is in Career mode, although I also flew in Free Flight this morning.

It seems like whatever the problem is, it gets worse over time, which leads me to believe it is not a graphics problem per se. I am running up against the MainThread limitation, which is another reason I believe this is a processing problem and not a graphics problem. Also, the audio crackles when it starts to slow down, with the crackling and pops getting worse as the framerate drops and the stuttering worsens.

One other note - not sure if this makes sense, but the framerate goes UP when I click off to another window. As in, 33-50% higher framerate while in that window. When I click back to the sim, the framerate goes back down to where it was. Last night, I saw 30fps when the sim was the active window, and 50-55fps when I clicked into another window.

1 Like
37

ISSUE DESCRIPTION

Description of the issue:

After setting up the sim I set rolling cache to a custom location and upped it to 64GB. After several flights which went just fine out of the sudden my performance dropped drastically especially on ground level (~10 FPS less on my mediocre system). Sound also started crackling on moving the camera around
I decided to delete the ROLLINGCACHE.CCC manually to see if the issue which persisted after restarting the sim will be gone right after which in fact was the case. I now left the file size at the initial 16GB to test it more.
After some time the performance started to be quite bad again, so I deleted the file yet another time with the same result and did that yet again right now which is why I file this report :wink:

[PC Only] Did you remove all your community mods/add-ons? If yes, are you still experiencing the issue?

Only a pretty limited selection is installed which was not removed.

FREQUENCY OF ISSUE

How often does this occur for you (Example: Just once, every time on sim load, intermittently)?

After quite some time depending on amount of data which was streamed.

REPRODUCTION STEPS

Please list clear steps you took in order to help our test team reproduce the same issue:

Precondition: set a custom rolling cache location like C:\MSFS\Rolling Cache which is similar to mine. Also use the high to ultra graphics preset so the cache won’t take too long to get filled.

  1. Perform some flights in some areas with loads of PG, at best at low level. Monitor performance each time
  2. Restart the simulator now and then in between flights - at some spot performance may drop
  3. Delete the ROLLINGCACHE.CCC file so a fresh one will be created
  4. Do another flight and compare performance to the flights before removal

YOUR SETTINGS

If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

What peripherals are you using, if relevant:

/

[PC Only] Are you using Developer Mode or have you made any changes to it?

Not in use to avoid influence from logging

[PC, MSFS 2020 Only] Are you using DX11 or DX12?

/

[PC Only] Many issues may be due to an outdated graphics card. Please state your Graphics Card Driver Manufacturer (NVIDIA, Intel, AMD) and Version:

Nvidia RTX 4070ti Super driver version 566.14

[PC Only] What other relevant PC specs can you share?

Intel i9 9900k @4.7GHz on MSFS sessions
64GB Corsair Vengeance LPX DDR4 4000 (all DIMM Sockets equipped)
Samsung SSD 970 EVO (2TB M.2)
Samsung SSD 980 PRO (2TB M.2)
Single 1440p SDR display connected through display port
PCIe Creative Soundblaster Z audio (7.1 surround mode)
MSI MPG Z390 Carbon AC Mainboard

Windows 11 24H2 with all current updates

MEDIA

Please add a screenshot or video of the issue occurring.

/

[END OF FIRST USER REPORT]

:loudspeaker: For anyone who wants to contribute on this issue, Click on the button below to use this template:

Do you have the same issue if you follow the OP’s steps to reproduce it?
•

Provide extra information to complete the original description of the issue:
•

If relevant, provide additional screenshots/video:
•

38

So I’ve had some good flights in the beginning.
I’ve always had some stutters and minor sound corruptions but nothing huge.

After a day or two of flights or so, I’ve been encountering what I can describe very audible sound corruptions. I’ve disabled Nvidia High def Audio device, tried uninstalling the nvidia app, etc. .

The one thing I didn’t try is reinstall Windows 11 23H2 (i have 24H2) but I’m not yet willing to reinstall windows for this game.

I’ve come across this thread in my troubleshooting and what I can say so far:

  1. Deleting the rolling cache has improved the situation
  2. Leaving the cache at the default 16GB has not eliminated audio stutters
  3. Reducing pre-caching to low with 16GB cache has made stutters worse
  4. Setting cache size to 120GB and going for ultra pre-caching has taken me back to my initial situation. I have stutters but no audio corruption or stutters other than minor here and there, much reduced.

System:

  1. 9800X3D
  2. 64GB RAM
  3. NVME for cache and game
  4. RTX 4070 Super
  5. When not stuttering I’m hitting 40-60 FPS with the current graphical settings with FG on
  6. Testing in: London EGLC 3rd party airport (found it to be a good repro site)

So there’s something with this cache.
Honestly, stutters are very annoying but audio stutters are simply painful.

3 Likes
39

Hey, sorry to hear you’re getting the same issues. After a while I’ve completely given up on the sim. I’ve not flown since Christmas. We faced all this in 2020 and to be back to fault finding in the next sim and having to be Beta testers on a game we paid so much for is frustrating. I’ve given up and maybe back in a few months to try again. Frustrating after putting over 3000 hours into 2020 and loving it the last few years after the initial teething problems. The new sim was supposed to be so much better. For most it’s just a buggy mess.

I jumped in last week as a test to see if the A300 inibuilds freezes were resolved also after a few months. Still does it every time I exit the plane. Freezes the whole sim.

Let’s hope the update that’s taken a while resolves a lot of issues.

3 Likes
40

The best solution would be to add a config option that allows disabling rolling cache as in FS2020 case.

Having to manage a several GB disk cache, with continuous reads and writes of all kind of data, not only scenery data, adds nothing but extra workload on end user systems. If it was used to preload scenery which is not yet rendered that could make sense but it´s just used to store data that you already used.

Why are all of us forced to use this feature? To save some server workload from users who fly in circles over the same city with same aircraft, same livery and same weather preset everyday during a whole week? I don´t think many users can really take advantage of this feature. At the end the cache needs to be constantly updated as soon as you change your aircraft or the flight location.

A much smaller RAM or VRAM cache only reused during the current game session would be faster and more efficient.

Cheers

1 Like
41

Hi guys.

I made a quick test to check the real streaming usage. It also includes rolling cache so that we can see if it helps or it just creates extra workload.

Cheers