qemu-kvm process is running at 100% CPU, but no response from guest

qemu-kvm process is running at 100% CPU, but no response from guest

[Ján ONDREJ (SAL)]

Hello,

  today I have second incident, that my qemu-kvm process is running at 100%
or 200% CPU (watched using top program), but there is no response from guest
long time (some hours). First time lots of these messages appeared in dmesg:

vcpu not ready for apic_round_robin
vcpu not ready for apic_round_robin
vcpu not ready for apic_round_robin

Second time nothing, only process was run at 200% CPU:

top - 06:23:14 up 4 days, 11:06,  1 user,  load average: 2.26, 2.15, 2.18
Tasks: 126 total,   1 running, 125 sleeping,   0 stopped,   0 zombie
Cpu(s): 50.2%us,  0.4%sy,  0.0%ni, 49.1%id,  0.2%wa,  0.0%hi,  0.1%si,
0.0%st
Mem:   8047368k total,  8004516k used,    42852k free,  1507160k buffers
Swap:  8388600k total,    57284k used,  8331316k free,    79700k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND           
17110 root      20   0 4417m 3.9g 1464 S 201.3 50.9   1326:34 qemu-kvm
 9886 root      20   0 2519m 1.9g 1376 S  1.7 25.1  72:40.73 qemu-kvm

Serial console without response too in boch cases, no ping to guest.

My current configuration is an fully updated Fedora 11 host and updated
Fedora 10 guest. KVM is from package qemu-kvm-0.10.5-3.fc11.x86_64.

I have no cpufreq or cpuspeed installed on my system, so there is no cpu
frequency scaling.

Other 2 similar host installations have no similar problems.

Thank you for help.

			SAL

Re: qemu-kvm process is running at 100% CPU, but no response from guest

[Amit Shah]

On (Thu) Jul 09 2009 [07:18:54], Ján ONDREJ (SAL) wrote:
> Hello,
> 
>   today I have second incident, that my qemu-kvm process is running at 100%
> or 200% CPU (watched using top program), but there is no response from guest
> long time (some hours). First time lots of these messages appeared in dmesg:
> 
> vcpu not ready for apic_round_robin
> vcpu not ready for apic_round_robin
> vcpu not ready for apic_round_robin
> 
> Second time nothing, only process was run at 200% CPU:
> 
> top - 06:23:14 up 4 days, 11:06,  1 user,  load average: 2.26, 2.15, 2.18
> Tasks: 126 total,   1 running, 125 sleeping,   0 stopped,   0 zombie
> Cpu(s): 50.2%us,  0.4%sy,  0.0%ni, 49.1%id,  0.2%wa,  0.0%hi,  0.1%si,
> 0.0%st
> Mem:   8047368k total,  8004516k used,    42852k free,  1507160k buffers
> Swap:  8388600k total,    57284k used,  8331316k free,    79700k cached
> 
>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND           
> 17110 root      20   0 4417m 3.9g 1464 S 201.3 50.9   1326:34 qemu-kvm
>  9886 root      20   0 2519m 1.9g 1376 S  1.7 25.1  72:40.73 qemu-kvm

What's the command line you used to start the guests?

> Serial console without response too in boch cases, no ping to guest.
> 
> My current configuration is an fully updated Fedora 11 host and updated
> Fedora 10 guest. KVM is from package qemu-kvm-0.10.5-3.fc11.x86_64.
> 
		Amit

Re: qemu-kvm process is running at 100% CPU, but no response from guest

[Ján ONDREJ (SAL)]

On Wed, Jul 15, 2009 at 12:51:33PM +0530, Amit Shah wrote:
> On (Thu) Jul 09 2009 [07:18:54], Ján ONDREJ (SAL) wrote:
> >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND           
> > 17110 root      20   0 4417m 3.9g 1464 S 201.3 50.9   1326:34 qemu-kvm
> >  9886 root      20   0 2519m 1.9g 1376 S  1.7 25.1  72:40.73 qemu-kvm
> 
> What's the command line you used to start the guests?

Guest was started using libvirt.

Looks that problem is somewhere in bounce code, more info in another thread:
  http://marc.info/?l=kvm&m=124756938002626&w=2
My CPU usage is growing after kernel panic. With panic=60 my guest is
restarted and runs some time again.

I am now experiencing with IDE dirves instead of virtio, so I can't send you
qemu-kvm original command line. With IDE drives there was no problem
tonight.

Thank you.

		SAL

Re: qemu-kvm process is running at 100% CPU, but no response from guest

[Amit Shah]

On (Wed) Jul 15 2009 [09:58:51], Ján ONDREJ (SAL) wrote:
> On Wed, Jul 15, 2009 at 12:51:33PM +0530, Amit Shah wrote:
> > On (Thu) Jul 09 2009 [07:18:54], Ján ONDREJ (SAL) wrote:
> > >   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND           
> > > 17110 root      20   0 4417m 3.9g 1464 S 201.3 50.9   1326:34 qemu-kvm
> > >  9886 root      20   0 2519m 1.9g 1376 S  1.7 25.1  72:40.73 qemu-kvm
> > 
> > What's the command line you used to start the guests?
> 
> Guest was started using libvirt.
> 
> Looks that problem is somewhere in bounce code, more info in another thread:
>   http://marc.info/?l=kvm&m=124756938002626&w=2
> My CPU usage is growing after kernel panic. With panic=60 my guest is
> restarted and runs some time again.
> 
> I am now experiencing with IDE dirves instead of virtio, so I can't send you
> qemu-kvm original command line. With IDE drives there was no problem
> tonight.

OK, the virtio-block code has a known bug which you might be hitting.

		Amit