Regression - X11 driver glXChooseVisual very slow, for each process

[cynar]

The X11 driver seems to be running into a performance regression:

X11 applications will call glXChooseVisual at the very start of the process, to set up for X11. Calling this has become _very_ slow - so slow, that on fast hardware it delays starting every single X11 process by about two seconds.

I am reproducing this on Fedora Linux (38 or 39) with the following simple steps:

ltrace -T --output=ltrace.log glxinfo64 -B
grep glXChooseVisual ltrace.log

This yields

glXChooseVisual(0x55b51abe2da0, 0, 0x55b519abb040, 0) = 0x55b51ac03f00 <1.657946>

with the number at the right flagging: 1.7 seconds startup delay from calling a function, where the call should effectively be "free".

Now, this is not a problem under Wayland - but I cannot use Wayland right now (no fractional scaling; challenges in interaction between KDE and VMware graphics stack)

[cynar]

FWIW, on a fresh Ubuntu LTS 22.04.3 this same call is

 564.412 ms [ 2932] | glXChooseVisual();

which is still ... not fast ... but one second faster than on Fedora 39.

Alas, OpenSUSE Tumbleweed, a fully rolling distribution, also gets to that very very annoying 1.7 seconds overhead / delay.

Finally, forcing software rendering completely eradicates these startup delays, but then that's software rendering.

I'd expect from all this that the VMware driver infrastructure and newer versions of the X11 server (in rolling distribution) do not interact well.

A fix would be very much appreciated for those who do their work _inside_ X11-based Linux distributions.

[Technogeezer]

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@cynar wrote:

I'd expect from all this that the VMware driver infrastructure and newer versions of the X11 server (in rolling distribution) do not interact well.

A fix would be very much appreciated for those who do their work _inside_ X11-based Linux distributions.

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 I too am seeing some very funny behavior when turning on 3D acceleration with X11 when running Fedora 39 beta on VMware Fusion. Not sure if that's a vmwgfx issue or Xorg.

Stuff still doesn't work with Wayland - including VMware drag/drop. It's still needed.

I'm hearing grumblings in the communities about GNOME developers wanting to remove all X11 support in a future release. https://news.itsfoss.com/gnome-wayland-xorg/  The future isn't looking too good for good old X11...

[cynar]

I totally like the idea of Wayland.

I am pained by the friction when I want to enable it (for KDE, on Fedora Linux, on VMware Workstation).

Sigh.

So, on the topic of this problem here, ... it seems as if Fedora Linux despises X11 enough to ship something ancient and heavily patched, where-as Ubuntu (even in 22.04 LTS) has a more recent (still old) baseline version.

And then there is ... Arch Linux. Or rather me trying EndeavourOS as in "make the install painless". What can I say:

 24.678 ms [ 19987] | } /* glXChooseVisual */

So, "glxinfo" starts about 70 times faster on Arch Linux than on Fedora Linux (38/39). No, I don't care about glxinfo, but I care a lot about any other X11 client having a two second delay on startup, be it Kate, Visual Studio Code, or Firefox.

I had always picked Fedora Linux to be reasonably up-to-date, an enormous amount of packages from an RPM-based distribution, similarity with Red Hat Enterprise Linux to reduce cognitive load.

Time to revisit my choice of distribution?

[cynar]

Fedora seems to be on a mission to not only nudge, but almost bully people into Wayland.

I believe Wayland is the right destination, but the path remains fraught with ... challenges.