[OpenNode-users] KVM Missing timer interrupts?

[<ope...@li...>]

Hello,

I have a working OpenVZ installation, and recently installed the kvm
packages from opennode. I managed to install 2 VMs, one with WinXP and
another with Win2003, both 32bits.

The problem is that the guests slows down when there is no network
traffic, and recovers when I, for example, ping flood the guest IP
address.

I don't know the cause, but it would seem that the guest is not
getting timer interrupts, and can only keep up when there is another
source of interrupts (network traffic).

Hardware Node:

# cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 23
model name	: Intel(R) Xeon(R) CPU           E5405  @ 2.00GHz
stepping	: 10
cpu MHz		: 2000.028
cache size	: 6144 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 4
apicid		: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm
constant_tsc pni monitor ds_cpl vmx tm2 ssse3 cx16 xtpr sse4_1 lahf_lm
bogomips	: 4000.05
clflush size	: 64
cache_alignment	: 64
address sizes	: 38 bits physical, 48 bits virtual
power management:

(There are 8 cores in total.)

#uname -a
Linux ns21xxxx.ovh.net 2.6.18-194.3.1.el5.028stab069.5 #1 SMP Tue May
18 17:48:31 MSD 2010 x86_64 x86_64 x86_64 GNU/Linux

# rpm -qa | grep kvm
etherboot-zroms-kvm-5.4.4-13.el5.centos
kmod-kvm-83-164.asys.8
kvm-83-164.asys.8
kvm-qemu-img-83-164.asys.8
kvm-tools-83-105.asys.22.4

Guest xml config:
<domain type='kvm'>
  <name>WinXP</name>
  <uuid>7f119fd1-bbf3-64f6-17d5-e5263b6a1502</uuid>
  <memory>1048576</memory>
  <currentMemory>1048576</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64' machine='pc'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <pae/>
  </features>
  <clock offset='localtime'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
[...] The rest is trivial, ide HD (raw image), ide cdrom, and e1000 network.

I initially installed XP with 2 vCPU. Changed it to 1 after reading
some posts regarding clock drifts... Didn't fix it, anyway.


This is the cmd line:
/usr/libexec/qemu-kvm -S -M pc -m 1024 -smp 1 -name WinXP -uuid
7f119fd1-bbf3-64f6-17d5-e5263b6a1502 -no-kvm-pit-reinjection -monitor
pty -pidfile /var/run/libvirt/qemu//WinXP.pid -localtime -boot c
-drive file=/home/KVM/WinXPVM.img,if=ide,index=0,boot=on,format=raw
-drive file=/home/KVM/NetKVM-and-viostor.iso,if=ide,media=cdrom,index=2,format=raw
-net nic,macaddr=52:54:00:6a:d4:af,vlan=0,model=e1000 -net
tap,fd=15,script=,vlan=0,ifname=vnet0 -serial pty -parallel none -usb
-vnc 127.0.0.1:0



Any idea on why it is happening?

Thanks in advance,
    Juilán J. M.

-- 
http://www.julianmenendez.es