Hello,
I experienced some performance problems on Xfce, slackware current. I wanted to change vblank_mode using and commands to see if it fixes it. It worked(it's smooth) but it completely broke xfce and now xfce starts with no window decorations and black screen and i have to run the first command to bring them back. Also every time i do this i get "Failed to connect to session manager: SESSION_MANAGER enviroment variable not defined." error


It works normally for different user(for root, but on different computer I managed to break root the same way.) Also everything works if before xfce i run KDE in different TTY(wierd). I tried replacing with root's or deleting xfce config files from user folder completely but it doesn't help.

I have exactly the same problem as "sgx45edaz4" in this thread: https://forum.xfce.org/viewtopic.php?id=13233
but I don't know how to "change it manually"/where the config file is.

I think "manually set it back to auto" just means to use the xconf-query command to set it to "auto" rather than "xpresent".

For what it's worth I set mine to xpresent months ago and had no trouble with it (slackware64-current). I'm using xdm and it dumps output from stuff it runs to ~/.xsession-errors which is where i'd look first but if you're not using that i dunno where they go. I see a file .xfce4-session.verbose-log as well which might be related but i don't know anything about it.

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thanks, ye I startx from text mode, no xdm.

The craziest thing is that removing all xfce packages with pkgtool and installing them from install USB didn't fix it. Once even KDE failed to run properly (blank screen with only mouse pointer) after I issued those commands but it "fixed iteslf" on second run) which leads me to think xfwm actually breaks something more than itself. Im out of ideas other than reinstall whole system. I'll try setting it to auto again then. If it doesn't work I'll reinstall OS, then test again which command exactly breaks it, when I know which one it is I'll just reinstall again and set it all up as good as i can without using this command. Turning compositing off completely with. works -no transparency and shadows but can live with that if it's really xfce's fault not mine nor can I do something about it.

I remember some thread about performance problems with glx happen because noveau uses vsync and glx uses it's own vsync and they interfeere with eachother or something but it's veague memory Im not sure what it really was or I just misunderstood something.

Could try clearing out stuff from .config before trying to re-install, if the packages are all replaced. Start with .config/xcfe4 .config/xfce4-session but maybe others.

Also perhaps trying to start X in manual steps to see what's failing (e.g. start the X server, then setup env vars and run xfce4-session or xfce4wm).

I had the desktop start running at a chuggingly slow and irregular frame-rate after some upgrade which is why i changed the setting. I'm using the amdgpu driver with an ancient "southern islands" gpu (GCN 1.0) so I guess it's not just nouveau driver related.