Intel AccelMethod UXA is much faster

User Support General
1

I’m using Intel HD Graphics 620 and Qubes was pretty laggy until I tried this which caused it to speed way up with no downsides I can see:

Option “AccelMethod” “uxa”

I’ve also tried these and they don’t seem to make a difference although technically they should be faster (TearFree is false by default but the last two are default true):

Option “TearFree” “false”
Option “TripleBuffer” “false”
Option “SwapbuffersWait” “false”

Is dom0 the correct place for all of this config?

Any other tips for increasing rendering performance?

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2

https://wiki.archlinux.org/title/Intel_graphics#Disabling_TearFree,_TripleBuffer,_SwapbuffersWait

Yes. This may change with sys-gui, but that is still a long ways off from being default or even stable.

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Also tried disabling the compositor in xfce but it didn’t seem to make a difference.

4

How exactly did you configure this in dom0? Via some kind of drop-in for xorg.conf?

I’d be interested to try whether this would help with more modern CPUs as well.

5

For AccelMethod = uxa to work, intel driver must be i915. It’s not better for modern CPUs…

EDIT:
I’ve checked Xorg.0.log nad it seems that uxa acceleration method is default (no need to set any option in xorg.conf) for modesettings intel driver.
Now I test sna.

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/etc/X11/xorg.conf.d/20-intel.conf
https://wiki.archlinux.org/title/Intel_graphics#Xorg_configuration

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I’ve made some more testing.
Dunno why with first test “UXA” accell poped as default for me.
I have i5-1245U 11th gen cpu with Iris gfx (no Xe yet), QubesOS r4.2.4 with Mesa 24.

When I delete /etc/X11/xorg.conf.d/20-intel.conf that was made by r4.1 installer (at first it was configured with intel DDX driver, but I’ve changed it to modesetting because it was too slow) then:

  • modesetting driver is used by default
  • glamoregl module is auto-loaded
  • glamor acceleration is auto-enabled
  • iris DRI/AIGLX is auto-enabled

If I configure xorg.conf this way:

Section "Device"
      Identifier   "Intel Graphics"
      Driver       "modesetting"
      Option      "AccelMethod"      "uxa"
EndSection

then:

  • modesetting driver is used
  • no acceleration is used
  • no DRI/AIGLX is set

So, setting of AccelMethod for intel gfx is viable only with Driver "intel" DDX driver which have terrible defaults and everything must be set/configured by user in xorg.conf and is not advised for Iris/Xe users.

BTW, this default Xorg configuration for Iris/Xe gfx assure no screen tearing with compositor enabled (default in QubesOS).

BTW2: with r4.1 installation and MESA 23 there was no default auto recognition and auto load of Xorg so making xorg.conf was mandatory

Dunno for other gfx makers.

PS: useful dom0 command to check what is used

cat /var/log/Xorg.0.log |grep -ie kernel.drivers -ie accel.*mesa -ie dri2 -ie aiglx
8

I tried modesetting instead of intel and it does seem a little faster.

9

Decided intel is faster.