[fedora-virt] Slow Jerky Guests

[Michael Kürschner]

Am 20.12.2010 15:28, schrieb Tom Horsley:
> There is a possibility that it has nothing to do with kvm
> but instead is an X problem with the kernel mode settings
> stuff. Is there one or more "kslowd" kernel processes
> accumulating lots of cpu time on your system? If so, might
> be suffering from:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=649960
>
> It made my whole system jerky (including the virtual
> machines) till I found the magic module option to disable
> polling.
I test your hint with the solution in these case. I build a new
initramfs with dracut but no improvement for the virtual machine.

I get the same problem like with an old kernel version. The machine
starts with BIOS output, but if the bootloader get start the OS, no
activities on disk (graph on disk E/A show nothing). The "real" CPU core
runs on 100%.  The virtual machine is a kvm host.

If I build a new virtual machine with the qemu hypervisor and the same
disk image, the virtual host starts.

The kvm module from kernel is loaded and kvm activ:

[root at blackwater ~]# lsmod | grep kvm
kvm_amd                29397  0
kvm                   213156  1 kvm_amd
[root at blackwater ~]# dmesg | grep kvm
[    8.312555] kvm: Nested Virtualization enabled
[    8.312559] kvm: Nested Paging enabled

A "virsh capabilities" command print this information: 
<capabilities>

  <host>
    <uuid>44323230-4439-5050-3530-4231ffffffff</uuid>
    <cpu>
      <arch>i686</arch>
      <model>Opteron_G3</model>
      <vendor>AMD</vendor>
      <topology sockets='1' cores='2' threads='1'/>
      <feature name='wdt'/>
      <feature name='skinit'/>
      <feature name='osvw'/>
      <feature name='3dnowprefetch'/>
      <feature name='cr8legacy'/>
      <feature name='extapic'/>
      <feature name='cmp_legacy'/>
      <feature name='3dnow'/>
      <feature name='3dnowext'/>
      <feature name='pdpe1gb'/>
      <feature name='fxsr_opt'/>
      <feature name='mmxext'/>
      <feature name='ht'/>
      <feature name='vme'/>
    </cpu>
    <migration_features>
      <live/>
      <uri_transports>
        <uri_transport>tcp</uri_transport>
      </uri_transports>
    </migration_features>
    <secmodel>
      <model>selinux</model>
      <doi>0</doi>
    </secmodel>
  </host>

  <guest>
    <os_type>hvm</os_type>
    <arch name='i686'>
      <wordsize>32</wordsize>
      <emulator>/usr/bin/qemu</emulator>
      <machine>pc-0.13</machine>
      <machine canonical='pc-0.13'>pc</machine>
      <machine>fedora-13</machine>
      <machine>pc-0.12</machine>
      <machine>pc-0.11</machine>
      <machine>pc-0.10</machine>
      <machine>isapc</machine>
      <domain type='qemu'>
      </domain>
      <domain type='kvm'>
        <emulator>/usr/bin/qemu-kvm</emulator>
        <machine>pc-0.13</machine>
        <machine canonical='pc-0.13'>pc</machine>
        <machine>fedora-13</machine>
        <machine>pc-0.12</machine>
        <machine>pc-0.11</machine>
        <machine>pc-0.10</machine>
        <machine>isapc</machine>
      </domain>
    </arch>
    <features>
      <cpuselection/>
      <pae/>
      <nonpae/>
      <acpi default='on' toggle='yes'/>
      <apic default='on' toggle='no'/>
    </features>
  </guest>

  <guest>
    <os_type>hvm</os_type>
    <arch name='x86_64'>
      <wordsize>64</wordsize>
      <emulator>/usr/bin/qemu-system-x86_64</emulator>
      <machine>pc-0.13</machine>
      <machine canonical='pc-0.13'>pc</machine>
      <machine>fedora-13</machine>
      <machine>pc-0.12</machine>
      <machine>pc-0.11</machine>
      <machine>pc-0.10</machine>
      <machine>isapc</machine>
      <domain type='qemu'>
      </domain>
    </arch>
    <features>
      <cpuselection/>
      <acpi default='on' toggle='yes'/>
      <apic default='on' toggle='no'/>
    </features>
  </guest>

</capabilities>

Is my machine not qualified to runs kvm nativ?

regards
Michael