Re: [patch] CFS scheduler, -v19

Ingo Molnar
2007-07-16T09:42:17Z

* Markus <lists4me@web.de> wrote:

> [...] The mouse is smooth, just when one app is being quit (dont know
> why...) the mouse will be jerking for a few seconds...

is the mouse jerky on any app quitting? Or is your observation the
following: _sometimes_ apps quit unexpectedly (their window just
vanishes?), and _at the same time_, the mouse becomes jerky as well, for
a few seconds?

the mouse typically only becomes jerky when there's some really high
load on the system - anything else would be a kernel bug. A jerky mouse
on an unloaded system is definitely a sign of some sort of kernel bug
(in or outside of the scheduler). An app vanishing unexpectedly might
mean an OOM-kill - but that would should up in the syslog as well.
Pretty weird.

Can you make this regression trigger arbitrarily, so that we could debug
it better? Apps exiting unexpectedly can be debugged via:

http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.22-rc6/2.6.22-rc6-mm1/broken-out/vdso-print-fatal-signals.patch

you can turn it on via the print-fatal-signals=1 boot option or via:

echo 1 > /proc/sys/kernel/print-fatal-signals

this feature will produce a small dump to the syslog about every app
that exits unexpectedly. Note that this might not cover all types of
"window suddenly vanishes" regressions.

Ingo