On Mon, 20 Jun 2016 22:55:35 +0200 Gaëtan Harter via arch-general <arch-general@archlinux.org> wrote:
On Mon, Jun 20, 2016 at 7:17 PM, Manuel Groß <mgr@nordkrater.de> wrote:
Hello there,
I currently experience a weird keyboard lag issue which I yet failed to resolve. I had some help looking into it a bit (and obviously searched the web), but we couldn't identify the speficic problem. I hope someone could provide me pointers or hints on what to test out.
I have a Thinkpad x250 running Arch Linux with Openbox and X11 on it. I use systemd-logind to log in, so X is started with the 'exec openbox-session' from my xinitrc. Not from some fancy lightdm or so. I do not have a certain date since when the issue occurs, but it has probably been a little over a month. I didn't make any major changes to my system then, and I do update regularly. This didn't occur when I set up the system.
The issue is, that on some, certain programs, the keyboard input 'arrives' too late, with delays up to 1-2s. In other programs, this never happens at all. And in rare occasions, it is even fine for programs, in which I experience the problem. I checked logs at obvious locations, but neither the systemd journal, dmesg or the Xorg log were screaming 'I have an issue here'. The trackpoint always works as excpected and the touchpad is disabled.
Programs where the delay occurs: * sakura * sublime * wireshark (qt5 version)
Programs which are fine: * claws-mail * geany * xterm * chromium
The delay also never occurs in the system shell (Alt+F2) and xterm, so it's not the shell or oh-my-zsh. The program lists suggests, that it is not a problem due to a specific version of GTK or QT, since programs using either library (or none of them) are affected.
I tried using 'libinput' instead of 'evdev' as a keyboard driver, but the change had no effect (I double checked the Xorg log which driver was actually used). In 'xev', all keystrokes arrive immediately.
So seems not to be the kernel or the driver, nor a specific gtk or qt library. The next thing to test would probably be the xlib and the libxcb themselves. So I used 'downgrader' to downgrade each a few revisions (also their lib32-libraries) and checked for a change, without success.
I don't know what to try next. Does anyone of you have an idea or already solved a similar issue? I'd appreciate any help on this.
Hi Manuel,
I have a Thinkpad T440p and I have the same issue with kernel 4.6, with both 4.6.2-1 and 4.6.1-XX versions. There is no issue with lts kernel 4.4.13-1.
From what I experienced, gnome-terminal is impacted, and I think also firefox.
Hello Gaëtan, thanks for your response! I just downgraded the kernel to 4.5.4-1, which I had installed before the 4.6 versions and was still available in my pacman cache. This seems to resolve the issue for me, too. Did you report a bug? I don't think I feel comfortable with bisecting the kernel on my productive system right now, but I'd still like to update my kernel in the future ;) -- Grüße/Regards Manuel Groß