Touchpad accel, spirals and xset

Paul Fox pgf at
Mon Jan 18 14:47:02 EST 2010

smith wrote:
 > On 01/18/2010 12:34 PM, Paul Fox wrote:
 > >   >  You are suggesting xset m 7/4 4? My tests where with 7/4 1...
 > >
 > > oh!  sorry -- i was mis-remembering.  you're correct that i
 > > previously recommended that the last element should be 1, and
 > > that's still correct.  (although in practice greater values
 > > probably won't be much different).
 > According to the man page the 2nd parameter is the threshold at which 
 > the acceleration value is applied so I'm not surprised that you don't 
 > see any difference between 0 and 1.  Even 4 might be hard to see.  I 
 > think that to see a difference for fine motor this value will have be in 
 > the 5 to 10 range.

martin isn't seeing a difference, which surprises me, because i
definitely saw a difference between 0 and 1.  from the wiki page
i wrote at the time:
    One would think that a threshold of '0' might cause behavior
    very similar to '1', but unfortunately that is not the case --
    '0' seems to be special.  Changing the xset line to "xset 7/4 1"
    results in much more predictable motion.

in more recent X servers, '0' is definitely special -- it invokes a
completely different (and more sophisticated) acceleration algorithm.
in the server we used on 802, it seemed to be different, but not
necessarily in a good way.

(i don't have an XO-1 nearby to test with right now.)

 paul fox, pgf at

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