mouse acceleration values smaller than "1" have no effect in Jaunty

Bug #367808 reported by klerfayt on 2009-04-27
This bug affects 4 people
Affects Status Importance Assigned to Milestone
x11-xserver-utils (Ubuntu)

Bug Description

"xset m 1/8 1" or "xset m 1/25 1" should make mouse cursor movement on the screen very slow, but instead mouse cursor acts similar if not exactly same as "xset m 1 1"

the bug does not seem to be hardware specific, Ubuntu 9.04 Jaunty Jackalope
Architecture: i386
 [ 14.077953] ppdev: user-space parallel port driver
 [ 14.120320] [drm] nouveau 0000:01:00.0: Allocating FIFO number 1
 [ 14.121307] [drm] nouveau 0000:01:00.0: nouveau_channel_alloc: initialised FIFO 1
 [ 22.808018] eth0: no IPv6 routers present
 [ 51.083535] CPUFREQ: Per core ondemand sysfs interface is deprecated - up_threshold
DistroRelease: Ubuntu 10.04
DkmsStatus: Error: [Errno 2] No such file or directory
GdmLog: Error: command ['cat', '/var/log/gdm/:0.log'] failed with exit code 1: cat: /var/log/gdm/:0.log: No such file or directory
GdmLog1: Error: command ['cat', '/var/log/gdm/:0.log.1'] failed with exit code 1: cat: /var/log/gdm/:0.log.1: No such file or directory
GdmLog2: Error: command ['cat', '/var/log/gdm/:0.log.2'] failed with exit code 1: cat: /var/log/gdm/:0.log.2: No such file or directory
InstallationMedia: Kubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100427)
Package: x11-xserver-utils 7.5+1ubuntu2
PackageArchitecture: i386
 Socket 0:
   no product info available
 Socket 0:
   no card
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-21-generic root=UUID=2f203cee-2fb9-435c-92c1-0dad373bb789 ro quiet splash
 PATH=(custom, no user)
ProcVersionSignature: Ubuntu 2.6.32-21.32-generic
Tags: lucid lucid
Uname: Linux 2.6.32-21-generic i686
UserGroups: 09/15/2005
dmi.bios.vendor: Insyde Software Corporation
dmi.bios.version: R1.02
dmi.board.vendor: MTC
dmi.board.version: A0
dmi.chassis.asset.tag: 12345678
dmi.chassis.type: 10
dmi.chassis.vendor: MTC
dmi.chassis.version: A0
dmi.modalias: dmi:bvnInsydeSoftwareCorporation:bvrR1.02:bd09/15/2005:svnMTC:pn:pvrA0:rvnMTC:rn:rvrA0:cvnMTC:ct10:cvrA0:
dmi.product.version: A0
dmi.sys.vendor: MTC
glxinfo: Error: [Errno 2] No such file or directory
 distro: Ubuntu
 codename: lucid
 architecture: i686
 kernel: 2.6.32-21-generic

Bryce Harrington (bryce) wrote :

Yes, I can reproduce this, although xset thinks it is handling fractions:

bryce@chideok:~$ xset m 1/25 4
bryce@chideok:~$ xset q | grep acceleration
  acceleration: 1/25 threshold: 4

Changed in xorg (Ubuntu):
importance: Undecided → Low
status: New → Triaged
Bryce Harrington (bryce) on 2009-04-28
affects: xorg (Ubuntu) → x11-xserver-utils (Ubuntu)
LarryRiedel (larry-riedel) wrote :

I have this problem too. I checked via "xinput get-feedbacks" to see the corresponding numbers are indeed consistent with the documentation at

Edward (edward-coffey) wrote :

I'm not sure how this functionality used to work, but this doesn't seem like a bug to me. Acceleration doesn't affect the base speed of the pointer when you're moving the mouse slowly, only when you move it faster. So acceleration less than 1 is saying "when I move my mouse faster, make the pointer move slower relative to my hand speed" which doesn't ever seem desirable.

To change the base speed of the pointer relative to hand speed you need to look at the ConstantDeceleration option. In modern systems it's set in an FDI file, typically /etc/hal/fdi/policy/10-x11-input.fdi (which doesn't exist by default in Ubuntu 9.04). I've attached a basic version - so far I haven't worked out how to get it to take effect without a reboot. I've used USB IDs to identify the mouse, since this is an option I regard as specific to a given piece of hardware - a different mouse might need different settings. Obviously you'll need to update it with your own USB IDs.

LarryRiedel (larry-riedel) wrote :

I think XPtrFeedbackState, accelNum, accelDenom have been around for 20 years or more. Maybe there should be a constraint that accelNum >= accelDenom, but it is not apparent to me where there should be.

“I'm not sure how this functionality used to work”

As I described: it made mouse pointer movements slower, so you could use high 1600 dpi mouse without lowering dpi to 400 with special utilities (if at all available).

<merge key="input.x11_options.ConstantDeceleration" type="string">4</merge>

will basically do same as if you used xset m 1/4 in older X window system (e.g. in 8.04 Hardy)... I think.

info.product string= of your device can be seen with command "hal-device"

Actually, Edward's 10-x11-input.fdi file was fine after changing attachment type from "text/html" to "application/xml". Sorry!

Traz (traz) wrote :

I'm not sure if this has some kind of relation with my problem. When I installed Jaunty I noticed I couldn't get rid of mouse acceleration. Well, I can, but it is really slow.

In previous versions, I could set the acceleration bar to he top and the threshold bar to the bottom and the mouse was fast and had no acceleration at all.

Bryce Harrington (bryce) on 2009-09-02
tags: added: jaunty

Small update for Ubuntu 9.10 Lucid Lynx.

Since it's much more cryptic (for me) to edit udev rules described @ - Configuration with udev (Ubuntu 10.04) - then I decided to use xinput:

# show connected devices
xinput --list --short

# show what properties can be changed
xinput --list-props Razer Razer 1600dpi 3 button optical mouse

# set constant deceleration
xinput --set-prop "Razer Razer 1600dpi 3 button optical mouse" "Device Accel Constant Deceleration" "4"

>Small update for Ubuntu 9.10 Lucid Lynx.

 correction: "Ubuntu 10.04"

Bryce Harrington (bryce) wrote :

[This is an automatic notification.]

Hi klerfayt,

This bug was reported against an earlier version of Ubuntu, can you
test if it still occurs on Lucid?

Please note we also provide technical support for older versions of
Ubuntu, but not in the bug tracker. Instead, to raise the issue through
normal support channels, please see:

If you are the original reporter and can still reproduce the issue on
Lucid, please run the following command to refresh the report:

  apport-collect 367808

If you are not the original reporter, please file a new bug report, so
we can work with you as the original reporter instead (you can reference
bug 367808 in your report if you think it may be related):

  ubuntu-bug xorg

If by chance you can no longer reproduce the issue on Lucid or if you
feel it is no longer relevant, please mark the bug report 'Fix Released'
or 'Invalid' as appropriate, at the following URL:

Changed in x11-xserver-utils (Ubuntu):
status: Triaged → Incomplete
tags: added: needs-retested-on-lucid-by-june

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tags: added: apport-collected
description: updated

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Bryce Harrington (bryce) on 2010-05-14
tags: added: kubuntu
tags: added: lucid
Launchpad Janitor (janitor) wrote :

[Expired for x11-xserver-utils (Ubuntu) because there has been no activity for 60 days.]

Changed in x11-xserver-utils (Ubuntu):
status: Incomplete → Expired

Erm, what did I do wrong? This is still an issue in all later Ubuntus after Jauntu.

Mikael Nordvall (iikael) wrote :

This issue is still present in Ubuntu 12.04.4 at least.

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