In my case there's a definitive difference between the two. GPU is Iris Plus 655 on Kubuntu 20.04.1. GZDoom is configured with dynamic lights, 1080p in OpenGL mode (Vulkan is slightly slower).KynikossDragonn wrote:I'd like to report that, I'm running on a Intel Iris Pro 580 for graphics and I don't get any performance loss using iris_dri rather than i965_dri. I'm currently on Mesa 20.2.3, judging by the name of the library itself I think the new iris_dri is geared towards Iris and Iris Pro graphics and not just the "Intel UHD" graphics family. I could be wrong though. I haven't run into anything other than maybe Blender that I need to manually override the driver to i915.bLUEbYTE wrote:Here's a tip for Linux users who have recent Intel iGPUs (Skylake+ I think) and with recent version of MESA (20+).
What happened is that with the latest Mesa drivers they switched to a new opengl driver backend called 'iris', from 'i965'. While this seems to have boosted performance in other workloads, in GZDoom and LZDoom I verified that this actually has a significant hit to FPS.
I even get 60 FPS in Total Chaos. Though it stutters a lot because Mesa's shader compiler is really slow apparently...
I hope it's okay to post this here to let other people know of my experiences with Intel graphics on Linux in regards to GZDoom.
FPS figures at the start scene of the map:
wine gzdoom.exe +vid_fps 1 +map map13 : 23 FPS
MESA_LOADER_DRIVER_OVERRIDE=i965 wine gzdoom.exe +vid_fps 1 +map map13 : 45FPS
I had observed a similar difference in native linux version as well, but I'm running the windows binary through wine because gamepad support in Linux is inferior.