xmodmap really slow

[Adam Jackson]

On Thu, 2018-07-26 at 12:25 +0100, Alan Hourihane wrote:
> Anyone tried just doing this recently....
> 
> xmodmap -pke > /tmp/keydump
> xmodmap /tmp/keydump
> 
> And watch the Xserver hang for quite some time.

Seems to be nearly instantaneous against an Xvfb, but did cause a
noticable hiccup with Xorg. Haven't investigated more closely, so I'd
suspect (in rough order of likelihood):

a) something super-linear in the number of input devices
b) some weird slow ioctl syncing the X state to the kernel
c) somehow you end up on the "lets spawn xkbcomp" path and the
fork/exec overhead kills you

- ajax