Some details here: https://gitlab.freedesktop.org/mesa/mesa/-/issues/9189

Hm, I don't think I did say it properly on my last comment, but with kernel 6.10, kde 6.1 and mesa-git I still had that issue on my 7900XTX. I did borrow my friends VRR monitor and didn't experience it then, so it's something to frame pacing on the output side somewhere. The game frame-graphs were super smooth though even while the stuttering was happening.

You need VRR / adaptive sync in general for any kind of smoothness.

Hm, when I booted a random SSD with windows I didn't have this issue, so just a hard VRR-requirement shouldn't REALLY the solution for weird behavior (although I will be getting a VRR one for in-game frame-drops and inconsistencies).

Fedora 39 didn't have this specific issue for some odd reason, only started happening on Fedora 40 for me.

I did test games with mesa-git via flatpak, but I assume that I need the 24.1 mesa driver actually on the whole system to fix this issue which is most likely caused by implicit sync. Guess I'll have to wait who knows for how long as I couldn't find an article for when the 24.1 driver will be in the fedora repos!

Quoting: zastrixHow did your stutter look like? Was it always stuttery or does it happen in an (not exactly set) interval? Like once every 10-30 seconds?

Hello. Sorry for my late response, I've been so busy.
My frame pacing issues were permanent as long as vsync was off, even with smooth frame time graphs. So this is resolved now when using explicit sync in KDE Plasma 6.1 Beta with appropriate Mesa version :smile:

Quoting: zastrixI assume that I need the 24.1 mesa driver actually on the whole system to fix this issue which is most likely caused by implicit sync.

Yes, and please remember your compositor also needs to support explicit sync.

Last edited by ridge on 8 Jun 2024 at 5:11 am UTC

Hey hey, no worries. Yep, sounds exactly like the issue I'm facing. Game is always hardlocked to a specific FPS via MangoHud and there's no changes in the frametime but still there are stutters present, sometimes HARD ones for half a second.

I did manage to run mesa-git on KDE 6.0.5 and the issue still happened. I did hear on reddit that fedora backported the explicit-sync functionality but I'm not exactly sure whether they did. I'll wait for KDE 6.1 and then run mesa-git and see if it's still an issue for me.

Quoting: zastrixI'll wait for KDE 6.1 and then run mesa-git and see if it's still an issue for me.

If you're feeling adventurous and/or particularly impatient, you could backport the patch yourself and build Kwin on your own 😀
I did that on a different machine for a friend, and it worked wonders.

Ahaha, thanks for the recommendation but I do run an immutable distro. What I CAN do is rebase to fedora rawhide and then overlay the mesa-git repos, I'd then have KDE 6.1 and the latest Mesa drivers.

... Actually as a matter of fact I *am* going to do that. Should be able to boot within, I don't know, 30 minutes?

I wanted to say that the issue is still present for me but it might be wrong? I did change to fedora rawhide and I still had the visual framedrop, but after that when I checked the 'about this system' menu I did see that it shows KDE Plasma 6.0.90 instead of 6.1, even though the initial KDE welcome menu did say 6.1, so I'm confused about this.

Quoting: zastrixwhen I checked the 'about this system' menu I did see that it shows KDE Plasma 6.0.90

That's the versioning scheme for betas. X.0.90 is the beta for the next version, X.1. But that's odd, since you're on the latest Mesa and a compatible compositor :0

I'll check when it comes to Fedora oficially, maybe because it was the beta there was an issue or something. Thankfully I can limit the FPS in the game engine in the game where I mostly feel the Vsync latency so it's okay, just a pain in the butt because I know I didn't have this issue until recently.

Don't think it's a HW issue as using Vsync fixes the problem.

Quoting: zastrixI'll check when it comes to Fedora oficially, maybe because it was the beta there was an issue or something. Thankfully I can limit the FPS in the game engine in the game where I mostly feel the Vsync latency so it's okay, just a pain in the butt because I know I didn't have this issue until recently.

Don't think it's a HW issue as using Vsync fixes the problem.

Just keep in mind, the frame pacing will be a lot better, but not 100% butter smooth. There will be very minor instances of judder, that is just the reality of pushing out as many frames as you can as fast as possible. When screen tearing with atomic modesetting is added to KWin, maybe it'll be even better.

If you really worry about frame pacing and smoothness in general - forget about screen tearing. More importantly, avoid monitors with 60 Hz. You should get a better one. There is literally no point in buying 60 Hz one today, since any recent screen with better refresh rate shouldn't cost a lot more than 60 Hz one.

Last edited by Shmerl on 11 Jun 2024 at 4:09 am UTC

I mean yeah. My monitor is 75Hz and I do plan to get a high-refreshrate, VRR enabled one. Namely the AOC CU34G2X/BK. Only reason why I won't buy it now is because I'm going to a festival next month which would cost me ~1000 euros.

It's just that I know that on Fedora 39 // KDE 5.27 I didn't have this issue of occasional stutter so I'm just boggled about it.

Maybe it *was* stuttering and simply had a placebo because I didn't have THAT great hardware then. I have a 7900XTX now and generally do expect to have constant FPS w/ 1080p@75Hz.

Stutters can actually happen in cases when game underloads the GPU due to GPU not sticking to high performance mode. I.e. ironically in some scenarios with a heavy loading game stutters are less likely to happen than with an average or low loading game.

There was some related amdgpu bug about it. One way to avoid that was to tell GPU to run in higher performance mode when you play such game (there are some perf profiles for that).

Last edited by Shmerl on 11 Jun 2024 at 3:49 pm UTC

Found the bug report: https://gitlab.freedesktop.org/drm/amd/-/issues/1500

Don't think it's that as I've tried to keep the GPU clock at around 2GHz. AFAIK it only affects the RX 6XXX GPU while I have a 7XXX GPU. Also the issue affects people regardless if vsync is used or not, for me when I use vsync I don't have issues.

Oh well, just gotta accept it until I get a VRR monitor.

Hm, trying to use `MAILBOX` Vsync didn't seem to help much. That's a vsync which is able to run at an uncapped framerite, still stuttering. Looks only specific Vsync's like FIFO fix the issue, weird.

Mailbox is supposedly broken in Plasma 5, but should be fixed in Plasma 6?

See https://bugs.winehq.org/show_bug.cgi?id=56002 and related.

I do use Plasma 6 though, 6.0.5 but tested as well with 6.0.90. Also as I don't use adaptive sync (yet), don't think that specific bug should affect me.