I use Ubuntu 10.04.2 LTS with xorg 1:7.5+5ubuntu1 and xserver-xorg-input-synaptics 1.2.2-1ubuntu4 To reproduce start a terminal and execute 1. killall syndaemon 2. syndaemon -i 4.0 -k 3. then press keys and move pointer with touchpad at once Two things go wrong: * syndaemon writes "Disable" and "Enable" to stdout, but enables not always 4.0 secs after the last keypress. * quite often the pointer still moves although syndaemon says it is disabled. Details have been well explained by Stanley Sokolow as comment #20 on http://launchpad.net/bugs/27541 which is one of many duplicates of http://launchpad.net/bugs/240738. The low default timeout of 0.5 secs in Ubuntu makes it even worse and seems a workaround for http://launchpad.net/bugs/801763 Due to recent diversity of touchpad hardware this bug gains publicity. I found that Macbooks, newer Samsung laptops and Asus EeePCs are among the affected systems. See my findings with Elantech touchpads in comment #27 of http://launchpad.net/bugs/240738
Not to toot my own horn here, but I contacted Peter Osterlund, the author of the syndaemon man page, and his response suggests that it isn't just a simple change of the default timing as suggested in comment 20 of the aforementioned bug: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input-synaptics/+bug/240738/comments/5
Did you try using the record extension instead of polling? syndaemon -R -i 4.0 -k
Using the undocumented option "-m 20" on syndaemon, as mentioned in LP #240738, made the situation a lot better for me. At least most keypresses are catched now.
(In reply to comment #2) > Did you try using the record extension instead of polling? > > syndaemon -R -i 4.0 -k If you press a key real quick it still misses it sometimes (apart from the fact that not being able to click for 4 seconds after the last letter you typed is very annoying by itself). I experimented with this undocumented switch -m to change the polling interval and running "syndaemon -R -i 0.5 -k -m 20", which changes the default polling interval of 200ms to 20ms, results in no more noticeable key presses being missed.
If you use -R, the -m argument is ignored.
(In reply to comment #3) > Using the undocumented option "-m 20" on syndaemon, commit 72d5b4886927aee5fbc871b5c3d0300be92d8ecc Author: Peter Hutterer <peter.hutterer@who-t.net> Date: Thu Jul 28 10:43:38 2011 +1000 man: document syndaemon -m switch
Closing as fixed as per comment #4. Since -m 20 is ignored if -R is given, I can assume that -R is enough to fix the issue. GNOME also uses the -R flag nowadays, see https://bugzilla.gnome.org/show_bug.cgi?id=639623 Long story short, any polling suffers from race condition, so this cannot be fixed in normal mode.
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