Latency when screensaver active

[Bill Moseley]

This is an odd problem and I'm hoping someone has ideas where to look.

I have a Thinkpad T60p that I sometimes will connect to my wired LAN,
boot the laptop and close the lid.  I then connect to it via ssh.

At the 10 minute mark when the screen saver kicks in the ssh session
exhibits latency -- it become very hard to type in my xterm as there's
quite a bit of delay when typing.  This will continue until 20 minutes
when dpms turns off the display.

What I typically do now is once I ssh in I run:

 XAUTHORITY=/var/lib/gdm/:0.Xauth /usr/bin/xset -display :0.0 dpms force off

to force the display off an then the latency goes away.

When the latency shows up there's no additional load on the machine,
no programs are showing up in top eating CPU, and I've strace'd a bunch of
processes trying to see what might be active all of the sudden without
luck.

Any ideas where I could look?

This is on Ubuntu Feisty.

X Window System Version 7.2.0
Release Date: 22 January 2007
X Protocol Version 11, Revision 0, Release 7.2
Build Operating System: Linux Ubuntu
Current Operating System: Linux tiger 2.6.20-16-generic #2 SMP Thu Jun 7 20:19:32 UTC 2007 i686
Build Date: 04 April 2007

# XAUTHORITY=/var/lib/gdm/:0.Xauth /usr/bin/xset -display :0.0 -q
Keyboard Control:
  auto repeat:  on    key click percent:  0    LED mask:  00000000
  auto repeat delay:  500    repeat rate:  30
  auto repeating keys:  00ffffffdffffbbf
                        fadfffdfffdfe5ef
                        ffffffffffffffff
                        ffffffffffffffff
  bell percent:  50    bell pitch:  400    bell duration:  100
Pointer Control:
  acceleration:  2/1    threshold:  4
Screen Saver:
  prefer blanking:  yes    allow exposures:  yes
  timeout:  600    cycle:  600
Colors:
  default colormap:  0x20    BlackPixel:  0    WhitePixel:  16777215
Font Path:
  /usr/share/X11/fonts/misc,/usr/share/X11/fonts/100dpi/:unscaled,/usr/share/X11/fonts/75dpi/:unscaled,/usr/share/X11/fonts/Type1,/usr/share/X11/fonts/100dpi,/usr/share/X11/fonts/75dpi,/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType,/usr/share/fonts/X11/misc,/usr/share/fonts/X11/100dpi/:unscaled,/usr/share/fonts/X11/75dpi/:unscaled,/usr/share/fonts/X11/Type1,/usr/share/fonts/X11/100dpi,/usr/share/fonts/X11/75dpi,/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType
Bug Mode: compatibility mode is disabled
DPMS (Energy Star):
  Standby: 1200    Suspend: 1800    Off: 2400
  DPMS is Enabled
  Monitor is On
File paths:
  Config file:  /etc/X11/xorg.conf
  Modules path: /usr/lib/xorg/modules
  Log file:     /var/log/Xorg.0.log





-- 
Bill Moseley
moseley at hank.org