mouse pointer acceleration without threshold?

Simon Thum simon.thum at
Mon Apr 13 05:55:19 PDT 2009

Harald Dunkel wrote:
> Sorry, but I do want to skip pixels (for gaming only, as written
> before). I understand that somebody overloaded (abused?)
> threshold = 0 to provide a completely different acceleration
> characteristic. I would like to have the "classic" profile with
> a "simple" characteristic and a zero threshold.
You can explicitly select the simple profile (via HAL/xorg.conf), so it 
accepts zero threshold. (xset m x/y >=1 is implicit)

> In the past I used 'xset m 7 1'. Threshold = 1 was close enough to
> zero for gaming, but with Xorg 1.6 this xset command seems to select
> a different acceleration profile than the old "simple" one. Is this
> correct?
More or less.  Old and new simple isn't exactly alike, it was changed a 
bit to provide more usability. Try the above, or else, switch to the old 
("lightweight") scheme. This will behave exactly as 1.5 did.

If you want to go wacky, make VelocityScaling large, e.g. >100. Then, X 
will think you're always moving your mouse very fast, giving you large 
acceleration. With 'xset m 7 1', that's 7. Other profiles won't really 
work then.

> How does xset affect the other profiles besides "classic"?
xset doesn't change the selected profile, but the two controls 
(accel/threshold) affect the selected profile. How exactly they do 
depends on the profile, best is to tweak until you like it :)

To get non-classic (to get rid of the threshold=/!=0-dichotomy) you'll 
need HAL or xorg.conf. In git versions you can switch live.

> BTW, Xorg.0.log says
> :
> (**) CHESEN PS2 to USB Converter: (accel) keeping acceleration scheme 1
> (**) CHESEN PS2 to USB Converter: (accel) filter chain progression: 2.00
> (**) CHESEN PS2 to USB Converter: (accel) filter stage 0: 20.00 ms
> (**) CHESEN PS2 to USB Converter: (accel) set acceleration profile 0
> :
> (II) XINPUT: Adding extended input device "Logitech USB Receiver" (type: MOUSE)
> (**) Logitech USB Receiver: (accel) keeping acceleration scheme 1
> (**) Logitech USB Receiver: (accel) filter chain progression: 2.00
> (**) Logitech USB Receiver: (accel) filter stage 0: 20.00 ms
> (**) Logitech USB Receiver: (accel) set acceleration profile 0
If you have two devices, install the xinput tool. Unlike xset, it works 

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