Bug#414322: linux-source-2.6.18: kernel freeze on disk i/o (regression)

[Lionel MOOG <lionel.moog@free.fr>]

maximilian attems wrote:
> tags 414322 moreinfo
> stop
>
>
> can you please try the 2.6.20 linux image from trunk buildserver
> see for aptlines -> http://wiki.debian.org/DebianKernel
>
> if there it doesn't work you'd need to bug upstream in
> bugzilla.kernel.org
>
> thanks for keeping us posted.
>
> --
> maks

Figaro wrote:
>
> This is due to the clocsourse set up. (Bug#412194: 
linux-image-2.6.18-3-k7:
>total system freeze after max. 10 minutes uptime).
>
>Add boot option: clocksource=tsc


Ok, I have some news,

I have tested the linux-image-2.6.20-1-k7 / linux-source-2.6.20 from trunk
buildserver. Although the 2.6.20 kernel is working without freezing entirely
the system, it still not really usable because of big latency issues 
with some
operations, like starting an X session.

For example, each time I launch KDE (from the shell with the startx command,
I do not have KDM installed), the entire system hang for a long time (black
screen, no disk activities, etc.) during the loading of the X server...


After some clocksource tweaking, as suggest Figaro, I can confirm this is a
timer clock issue and not another problem :

1) cat /sys/devices/system/clocksource/clocksource0/current_clocksource
  reveals that the timer clock is based on "pit" by default in the 2.6.18
  kernel

2) cat /sys/devices/system/clocksource/clocksource0/current_clocksource
  reveals that the timer clock is based on "jiffies" by default in the 
2.6.20
  kernel

3) simply switching to "tsc" these default timer clock values solves the 
freeze
  and the hang problem in both 2.6.18 and 2.6.20 kernels.


To resume :
   - clocksource=pit      ->  freeze issues
   - clocksource=jiffies  ->  latency issues

So please, I suggest that you use / enable the "tsc" clocksource by 
default for
the upcoming kernels versions related to the k7 architecture.


THR4K