Ok, this is really strange. I have a pretty bare setup of ubuntu where I start awesomewm and a number of other programs from an .xsession. I'm not running Gnome 3 or anything heavy like that and I've even stopped as many running processes as can to try to figure out what's causing this, to no avail.

What I'm seeing is, after maybe an hour after booting my laptop keyboard input gets slow. It's almost like it's adding a 300ms timeout to every keystroke, as if it's waiting for some other keystroke that will trigger some magic combination. If I just type quickly I can't see it for anything except the final keystroke which takes 300ms-1s to display. It's hard to time it, obviously. Weirder still, if I look at a terminal with a blinking cursor I can see that the blinking is not constant. Normally I think it's something like 1s on 1s off, but now it is totally sporadic.

I was worried it would be a hardware issue, but when I use a real terminal (ie not in Xorg, Ctrl-Alt-F1, the problem is gone. dmesg doesn't really say anything interesting. Neither does /var/log/Xorg.0.log.

Anyone have any ideas? I think this might be easier to solve in realtime; I'm frew on freenode. Feel free to ping and maybe you can help (and of course write what worked here and get the credit.)

  • Have you checked, e.g., top or some other system monitor to see if the cpu usage and load average are within normal limits? – goldilocks Jul 12 '14 at 21:54
  • What makes you think it's the keyboard and not the display? Does top or iotop show heavy CPU usage or I/O? – Gilles 'SO- stop being evil' Jul 12 '14 at 22:05
  • If you want to chat, around these parts, you're more likely to find someone willing to do so in our chatroom than on IRC. – Gilles 'SO- stop being evil' Jul 12 '14 at 22:06
  • yeah, top, iotop, etc have basically nothing interesting. That was my first thing I looked at :) And I'll try the chatroom shortly – Frew Schmidt Jul 13 '14 at 18:49

Turns out that for some reason Ubuntu had enabled Mir on my laptop. Uninstalling and restarting X fixed the issue permanently.

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