[arch-general] Keyboard lag issue

[Bruno Pagani]

Le 20/06/2016 à 22:55, Gaëtan Harter via arch-general a écrit :

> On Mon, Jun 20, 2016 at 7:17 PM, Manuel Groß <mgr at 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.
>> --
>> Grüße/Regards
>> Manuel Groß
>>
> 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.
>
>
> Regards,
> Gaëtan Harter

Did you have a look at these:

https://bugs.archlinux.org/task/49431
https://bugs.archlinux.org/task/49623

? If not, try disabling fbc. Eventually report upstream if it still
hasn’t been done (I’m not affected myself, so…).

Bruno

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