Recent qemu and timers issue

[Jedrzej Kalinowski]

Dnia sobota 04 kwietnia 2009 o 00:23:29 Juergen Lock napisał(a):
> In article <c948bb4de85d1b2a340ac63a7c46f6d9 at iem.pw.edu.pl> you write:
> >Hi all,
> >
> >When running FreeBSD 8-CURRENT system inside a qemu machine (from the
> >latest port by nox at freebsd.org) I have strange timer problems in the
> >virtual machine.
>
> What is the host running, also current?

Yes, the host is also running current. 

But the same host has no problem with older FreeBSD kernels on the guest, eg. 
FreeSBIe 1.1 or FreeNAS (kernel  v.6.4)

>
> >My logs and console are full of messages like this:
> >calcru: runtime went backwards from 11248014678717988 usec to 119242 usec
> >for pid 60 (ps)
> >
> >calcru: runtime went backwards from 11248014678921829 usec to 2516605 usec
> >for pid 60 (ps)
> >calcru: runtime went backwards from 7014844 usec to 6270851 usec for pid 0
> >(kernel)
> >
> >It even happens for some processes to die inside qemu guest.
>
>  Is this an smp host?  You could try forcing qemu onto one cpu by
> doing like:
> 	cpuset -l 0 qemu ...
>

Yes, it's an smp host (8 cpus). But cpuset -l 0 qemu ... (also -clock 
dynticks) didnt't help.

> >I tried to use all possible timers using sysctl, where I have:
> >TSC(800) HPET(900) ACPI-safe(850) i8254(0) dummy(-1000000)
> >None of these helped.
>
>  On the host or in the guest?
>

It's in the guest machine., where I tried these settings 

One important thing I forgot to mention in my initial posting:
When I run 'systat -vm 1' o the guest machine - it's almost fully loaded - and 
80% (or more) of it's cpu time is spent in interrrupt handling! This is also 
not the case with older kernels.

> [snip]
> >I would greatly appreciate any help or a hint - where should I look for
> >help on this issue.
>
>  If none of these help you could also try the qemu list:
> 	http://lists.nongnu.org/mailman/listinfo/qemu-devel
> (I think you can still post without being subscribed, altho in that case
> it may take a while for the post to get thru.)
>
>  HTH,
> 	Juergen

At this moment it's very hard for me to judge if it's qemu or kernel issue..
Any thoughts?

Thanks,
Jędrzej Kalinowski