[2.0.57] Dramatic Wayland rendering performance issue on KDE Plasma 6.4

[wavefront32]

I just updated my system to KDE Plasma 6.4 and the rendering performance of Factorio using the Wayland backend has seriously degraded. The performance of the X11 backend appears to be the same as before.

I haven't attached a save file because you can reproduce in a brand new standard scenario game, or just from the main menu.

Operating System: Arch Linux
KDE Plasma Version: 6.4.0
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1
Kernel Version: 6.15.3-2-cachyos (64-bit)
Graphics Platform: Wayland
Processors: 32 × AMD Ryzen 9 9950X3D 16-Core Processor
Memory: 64 GiB of RAM (62.4 GiB usable)
Graphics Processor: NVIDIA GeForce RTX 4090
Manufacturer: ASUS

[Rseding91]

That 100% sounds like a KDE Plasma developer issue given *we* didn't change anything and it got worse with their update.

However, I'll leave this for the linux guys to decide.

[wavefront32]

I agree it’s likely a KDE Plasma or SDL issue, but just in case it isn’t I also filed a bug here. Factorio is one of the few games that supports the Wayland SDL backend!

[orangep9]

Same issue here with plasma 6.4 on arch. Has anyone made a report on the plasma side?

Edit: Also is there any way to debug what went wrong here easily? It seems like making a bug report that says "Factorio rendering performance is terrible on plasma 6.4 using wayland as the preferred video driver!" could use more details.

[wavefront32]

Same issue here with plasma 6.4 on arch. Has anyone made a report on the plasma side?

Edit: Also is there any way to debug what went wrong here easily? It seems like making a bug report that says "Factorio rendering performance is terrible on plasma 6.4 using wayland as the preferred video driver!" could use more details.

I plan to file a bug tonight. Just haven’t had the time yet.

I also haven’t had the time to setup profiling, but maybe I will if either the folks here or at KDE need more information.

[wavefront32]

KDE Plasma bug: https://bugs.kde.org/show_bug.cgi?id=505954

[Jap2.0]

Factorio is using software rendering (llvmpipe) instead of your GPU. If you're using the same version of Factorio as before the update, that seems like either a Plasma issue or a Mesa issue.

[wavefront32]

Factorio is using software rendering (llvmpipe) instead of your GPU. If you're using the same version of Factorio as before the update, that seems like either a Plasma issue or a Mesa issue.

I didn't even notice that line in the log. That certainly explains the slow rendering. Using the same version of Factorio. Since I'm using an Nvidia GPU, Mesa should not be very involved (beyond the vendor-neutral loader I think).

Still hoping to get time sooner to run a few more tests. I'd like to try a non-Steam version in particular with instrumentation and/or a debugger.

[Jap2.0]

I didn't even notice that line in the log. That certainly explains the slow rendering. Using the same version of Factorio. Since I'm using an Nvidia GPU, Mesa should not be very involved (beyond the vendor-neutral loader I think).

Still hoping to get time sooner to run a few more tests. I'd like to try a non-Steam version in particular with instrumentation and/or a debugger.

Ah, sure. I have a habit of saying "Mesa" instead of "your graphics driver" when talking about Linux... I don't know if that gets updated at the same time as Plasma or not though.

[wavefront32]

The issue appears to in fact only reproduce with the Steam version of the game. Even with the Steam overlay disabled, the llvmpipe OpenGL implementation gets picked. The same game version downloaded from the web site with the same config properly loads my GPU vendor (Nvidia)'s OpenGL driver.

I am currently in the Steam client beta channel. I will switch to stable and see if it reproduces.

Steam Beta Branch: Steam Beta Update
Steam Version: 1750726487
Steam Client Build Date: Mon, Jun 23 16:25 UTC -08:00
Steam Web Build Date: Mon, Jun 23 17:48 UTC -08:00
Steam API Version: SteamClient022

[wavefront32]

It does reproduce with the Steam client stable channel as well.

Steam Beta Branch: Stable Client
Steam Version: 1747701111
Steam Client Build Date: Mon, May 19 12:51 UTC -08:00
Steam Web Build Date: Mon, May 19 17:21 UTC -08:00
Steam API Version: SteamClient022

[orangep9]

Same thing here. Running the game on steam through gamescope also fixes the issue.

[wdimble]

I updated to KDE Plasma 6.4.1 this morning, and the issue appears to have been fixed there.

[raiguard]

Thanks for the reports. After several weeks, borrowing a NVIDIA GPU from my cousin, and communicating with a KDE Plasma developer, I have narrowed this down to a bug either in SDL, the Steam Linux Runtime, or the NVIDIA driver. In either case, it is out of our hands to fix. I forwarded my findings to my Plasma contact and they will take it from here.

The issue has to do with KDE Plasma disabling wl_drm support in 6.4. This is supposed to be deprecated and optional, but something is going wrong between SDL, Steam, and Plasma that is causing it to fall back to llvmpipe software rendering. Plasma temporarily reverted this change in 6.4.1, but they aim to find a proper fix for future versions.