7.0-PRERELEASE desktop system periodically freezes momentarily

Joe Peterson joe at skyrush.com
Wed Jan 23 07:28:11 PST 2008

Wayne Sierke wrote:
> So it seems the only thing of interest that I"ve managed to capture so
> far pertains to glxgears - an instance of the "stutter" and a part of a
> short freeze when dragging its window. Unfortunately these frequent
> mouse disconnects make it difficult to recognise genuine freezes during
> 'normal' use, if indeed they are still occurring with RELENG_7. However
> the glxgears behaviour remains (apparently) the same as it was on
> RELENG_6. Whether that's a telling sign or not remains to be seen.

Wayne, thanks for continuing to investigate, since these little
"freezes" definitely affect usability.  If I can help in any way, let me
know.  I have not made any further graphs, but I continue to see
intermittent mouse freezing (for short sub-seconf periods, usually).  As
for mouse disconnects, I don't know if that is what I am seeing, but one
thing I do notice is that the keyboard is also affected (easily seen by
holding down a key and letting it repeat - short pauses can be seen in
the echo, which could be xterm, X, or the keyboard input, of course).
Also, I tried unplugging my ps/2 mouse and using a USB one instead -
same issue exists.

In case this is scheduler-related, I tried running a CPU-hogging task
(xtrs in "model 4" mode, which spins, polling for input).  While running
this and moving the mouse rapidly between two windows (I use
focus-under-mouse, so this causes focus events), I eventually get
repeated short mouse freezes for quite some time (maybe 10 seconds)
until things can catch up.  This is not reproducible on Linux CFS
(2.6.23) - the CPU use certainly affects event "catching up" in X, but
the mouse stays smooth.

Also, it seems that intermittent mouse freezes happen more often when
I've been away from the machine for a while and return to start using
the mouse again, but that's not always the case.  A few short
freezes/stutters happen a second or so after mouse movement resumes.


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