Touchpad sucking CPU when touched

[humdinger]

This is hrev41255.

Probably since the recent work on the synaptics/touchpad, input_servers "Ps/2 Touchpad 1" thread consumes about 15% CPU in my Core2Duo when the touchpad is in use. I don't think there was a visible usage-increase before...

[czeidler]

Could you please check if it really comes from my changes? Can't imagine where this should could come from. Can't see the usage increase with ALPS...

thx!

[taos]

Using hrev41256 (gcc2hybrid) with an old centrino notebook (Pentium M 1,3 GHz, 1280 MB RAM) with Synaptics Touchpad.

Top command in terminal shows a cpu usage of

• ca. 15 % for thread "Ps/2 Touchpad 1 watcher", while using 2-finger-scrolling with touchpad (see "top_touchpad.txt").
• < 1 % for thread "USB Mouse 1 watcher", while using scroll wheel of usb mouse (see "top_usb_mouse.txt").

For comparison, the output of top with hrev37573:

• < 1 % for 2-finger-scrolling with touchpad (see "top_touchpad_old.txt")
• < 1 % for scrolling with usb mouse (see "top_usb_mouse_old.txt")

[humdinger]

I tried the nightly hrev41185, but couldn't get it to finish the bootup, because of that synaptics crash you have fixed with a later commit.
I then went further back to hrev41122, which should be before all your touchpad works. That one boots up and shows a CPU usage of just 0.1%, similar to taos' findings. It seems something of your changes did do the damage. :)

[humdinger]

When using the touchpad, I have my syslog filled with tons and tons of things like

KERN: ALPS: movement set buttons
KERN: ALPS: tap gesture timed out
KERN: ALPS: movement event
KERN: ALPS: movement set buttons
KERN: ALPS: tap gesture timed out
KERN: ALPS: no touch event
KERN: ALPS: tap drag gesture timed out
KERN: ALPS: tap gesture timed out
KERN: ALPS: no touch event
KERN: ALPS: tap drag gesture timed out
KERN: ALPS: tap gesture timed out

May this excessive debugging info be the cause of the CPU suckage?

[czeidler]

ah jetzt ja! that sounds like the only reasonable explanation. Could you check my last commit? thanks!

[humdinger]

Perfect! That was it, everything's back to normal, i.e. 0.1% usage. Thanks very much!

[czeidler]

cool