keyboard input lag with single monitor only (intel)

meccanus · 2014-07-04 08:04:59

For the past few months I have been facing a strange issue I can't really figure out.
I own a thinkpad x200t with an intel graphic card and use openbox mixed with parts of kde (and gnome too). I'am currently using kernel 3.14.6-2-ck

Most of the time the laptop is attached to an external monitor and works well.
Whenever I work in single monitor mode, keyboard input lag (and graphic lag in general) makes it impossible to accomplish anything.
Example problems include:
- in krunner or gmrun or emacs I can write about 20 letters before they star appearing on the screen (hence the issue seems to affect both gtk an qt apps)
- i can't use softwares like PDF exchange viewer run in wine or Kingsoft Office (wps office) because they almost don't refresh any element of their interface at all

In general, alt-tabbing seems to force a refresh

Problem persisted
- over various kernel upgrades (both minor and major)
- even when returned to openbox from openbox-multihead
- even when i removed every configuration from /etc/X11/xorg.conf.d/20-intel.conf

dmesg, x11.log do not provide any useful information. I checked /sys/firmware/acpi/interrupts/* and disabled the highest one

What truly baffles me is the different behavior between dual monitor and single monitor.

Any hints on what I could check?

ConnorBehan · 2014-07-05 00:41:05

Sounds very strange. I assume performance is fine if you have a dual monitor setup and simply unplug the second monitor. Starting X with only one monitor is what does it right?

If so, please post your Xorg.0.log files in both cases. To check if the lag is purely due to display of text, you can run "x11perf -aa10text" or some other benchmark.

meccanus · 2014-07-05 20:44:44

No. If I use xrandr and unplug the second monitor, the interface becomes sloppy. If I plug back the second monitor and use xrandr to adjust the setup, then everything is back to normality. I thought I had messed up with some config, however today I upgraded the kernel to 3.15.3-ck and it seems to me everything is work fine right now. I haven't tested all scenarios thoroughly (e.g. after a suspend cycle) but the main issue disappeared: i can swap to single monitor mode and keep working without lag.

I'll have a couple of days of test and eventually mark it as solved.

(By the way, I had a look at x11perf before updating, but couldn't interpret the results).

thank you for your time.

katratxo · 2015-10-16 08:51:34

Hi,

I'm facing the same issue with a Thinkpad X230, but the lag only happens with QT based applications. Reported here: https://bbs.archlinux.org/viewtopic.php?id=203828

I tried connecting an external monitor (enabled using xrandr) and the lag is gone in the laptop/primary monitor, but keeps happening when I move the application to the external one.

Kernel: 4.2.3-1-ARCH
xf86-video-intel: 1:2.99.917+478+gdf72bc5-2

Any ideas on where to report the issue?

Thanks,

Arch Linux

#1 2014-07-04 08:04:59

keyboard input lag with single monitor only (intel)

#2 2014-07-05 00:41:05

Re: keyboard input lag with single monitor only (intel)

#3 2014-07-05 20:44:44

Re: keyboard input lag with single monitor only (intel)

#4 2015-10-16 08:51:34

Re: keyboard input lag with single monitor only (intel)

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