Adaptive acceleration for touchpad on Ubuntu 17.10

In 17.10, you can also set the acceleration profile directly and disable mouse acceleration by setting accel-profile to 'flat'

gsettings set org.gnome.desktop.peripherals.mouse accel-profile 'flat'

Alternatively, use dconf-editor:

For this, try editing the key speed from the schema org.gnome.desktop.peripherals.touchpad. The description for the key is as follows:

Pointer speed for the touchpad. Accepted values are in the [-1..1] range (from "unaccelerated" to "fast"). A value of 0 is the system default.

which strongly indicates the gnome key has something to do with touchpad acceleration. Use the dconf editor or gsettings through the command line and see if modifying this key has any effect.

Edit: Sorry this only helps if you're using Xorg, not Wayland according to Arch Linux' Wiki:

For Wayland, there is no libinput configuration file. The configurable options depend on the progress of your desktop environment's support for them; see #Graphical tools.

For Xorg, a default configuration file for the wrapper is installed to /usr/share/X11/xorg.conf.d/40-libinput.conf. No extra configuration is necessary for it to autodetect keyboards, touchpads, trackpointers and supported touchscreens.

For Xorg:

According to its man page libinput also supports adaptive acceleration:

You should be able to add it as an option in xorg.conf, e.g. /usr/share/X11/xorg.conf.d/40-libinput.conf:

Option "AccelProfile" "adaptive"