[Qemu-devel] qemu with kqemu freezes when more than one qemu is running

[Qemu-devel] qemu with kqemu freezes when more than one qemu is running

[Frank J. Beckmann]

Hi, 
 
qemu-0.8.1_1 with kqemu-kmod-1.3.0.p9 on FreeBSD 6.1-RELEASE i386 freezes 
after less than one hour runtime when more than one qemu is running. If only 
one qemu is running everything works fine. When more than one qemu runs none 
of them can use kqemu without freezing after a short time. The frozen qemu 
can get killed only by a kill -9. The same happened with kqemu-kmod-1.3.0.p7. 
 
The processor is an AMD Athlon 64, but I use the i386 release of FreeBSD. 

The problem was also confirmed by somebody else:
http://qemu.dad-answers.com/viewtopic.php?t=1726&sid=66fb41f3f20e19862aed3ae2fbfe97e9
 
Please help me. 
-- 
Bye
Frank

Re: [Qemu-devel] qemu with kqemu freezes when more than one qemu is running

[Bakul Shah]

"Frank J. Beckmann" <frank@barda.agala.net> wrote:
>  
> qemu-0.8.1_1 with kqemu-kmod-1.3.0.p9 on FreeBSD 6.1-RELEASE i386 freezes 
> after less than one hour runtime when more than one qemu is running. If only 
> one qemu is running everything works fine. When more than one qemu runs none 
> of them can use kqemu without freezing after a short time. The frozen qemu 
> can get killed only by a kill -9. The same happened with kqemu-kmod-1.3.0.p7.
>  
>  
> The processor is an AMD Athlon 64, but I use the i386 release of FreeBSD. 

I ran two plan9 guests for over two hours now on my laptop
with no crash.  They are both doing a ping every 10 ms and
continuous floating pt additions.  kqemu is enabled but not
kernel-kqemu (as plan9performance under kernel-kqemu is
abysmal).  This is a Pentium M machine with 1GB of memory,
running FreeBSD-current.  plan9 is not very resource hungry
(RSS is about 70MB) so if this is a resource related problem
my test won't catch it.

A quick reading of kqemu-freebsd.c does not reveal any problems
for a uniprocessor machine (but I am not too sure of SMP).

Can people who are seeing crashes or hangs provide some more
information?

- symptom: (host crashes, guest crashes, guest hangs, guest loses its mind)
- freebsd version (also if UP or SMP version)
- processor
- command line used to invoke each qemu instance
- what guest oses are run when this happens
- if this is triggered more often by specific guest programs
- what happens if you run the same guests with less memory.
- output of sysctl kern.smp.cpus
- VSZ and RSS of these images (from ps axlw).
- whether -kernel-kqemu was used

I am hoping a pattern will emerge that will help us debug this.