Re: [coLinux-users] Colinux 0.7.2 hangs on startup XP

[Henry N. <Hen...@Ar...>]

Paolo Minazzi wrote:
> Hi Henry,
> 
> I checked my old kernel configuration of 0.7.1 that was very very
> stable .... Never an hang of my system !
> 
> I had
> 
> #
> # IO Schedulers
> #
> CONFIG_IOSCHED_NOOP=y
> CONFIG_IOSCHED_AS=y
> CONFIG_IOSCHED_DEADLINE=y
> CONFIG_IOSCHED_CFQ=y

And what is the CONFIG_DEFAULT_IOSCHED="..."?

> CONFIG_PREEMPT=y
> CONFIG_PREEMPT_BKL=y
> 
> as you say.
> 
> This is the real thing. It is not the theory. The old configuration was stable.
> 
> But I cannot understand why  disabling CONFIG_PREEMPT and
> CONFIG_PREEMPT_BKL can produce deadlocks (or have more chances to have
> deadlocks).

Help for "CONFIG_PREEMPT_BKL" from kernel source:
"This option reduces the latency of the kernel by making the
big kernel lock preemptible."

This, I read, that a "big kernel lock" can be interupted. Right? And in
your case the PC hangs without accepting any interrupts (keyboard). A
simple "big kernel lock" is a simple disable all interrupts. Perhaps the
 CONFIG_PREEMPT_BKL helps to not hang in such lock.

CONFIG_PREEMPT needs to have CONFIG_PREEMPT_BKL.

> I decided to disabling these because I am not interested in improving
> the responsivity of my colinux. I am only interested in performance.
> 
> Today I'll reconfigure as you saied me.

I have only checked differences between your and the default config and
listened candidates for problems. A highly candidate is the io scheduler.

After you have enabled all the io schedulers, you can select ones with
the kernel boot option "elevator=deadline", default is
"elevator=anticipatory".

Yes, of curse, perhaps there exist a bug and nobody has seen it. You can
use your scheduler (DEADLINE) and all other configs. But please, then
should enable the CONFIG_DEBUG_KERNEL to find the daedlog, instead
hanging in it.

-- 
Henry N.