Re: SOLVED Re: Sloow blender on FreeBSD (vs Ubuntu)

Harry Schmalzbauer <freebsd@omnilan.de> writes:

> And regarding performance, I'd like to share that
> using x11-drivers/xf86-video-intel slows down XFCE4 by some orders of
> magnitude compared to the 'modesetting' (xorg builtin component)
> driver.

This is a known issue with xf86-video-intel defaults:
- upstream disables DRI3 by default, requiring downstream to pass --with-default-dri=3
- FreeBSD port disables SNA by default (see comment about --with-default-accel=uxa)

I have the following in xorg.conf(5) from >4 years ago (no longer dogfood Xorg):

  Section "Device"
          Identifier "integrated_card"
          Driver     "intel"
          Option     "AccelMethod" "SNA"
          Option     "DRI" "3"
          Option     "TearFree" "false" # redundant with x11-wm/picom
          Option     "TripleBuffer" "false" # lower latency and maybe unnecessary with x11-wm/picom
          BusID      "pci:0:2:0" # hint for multi-GPU setups
  EndSection

See also https://lists.freebsd.org/pipermail/freebsd-x11/2021-May/028125.html
which affects both modesetting and xf86-video-intel but so far no one reproduced.
Nowadays, modesetting causes stutters for me unless LIBGL_DRI3_DISABLE=1.
Xorg perf regressions likely come from mesa-dri and drm-kmod updates but
the latter is non-trivial to bisect as LinuxKPI is a moving target.