Re: kvm very slow

Ulrich Schreiner
2007-08-01T19:45:52Z

dmesg|grep kvm

SELinux: initialized (dev kvmfs, type kvmfs), uses genfs_contexts
kvm: emulating exchange as write

now booting into a F7 image, after the system is ready (and in idle):

top
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
14917 root 20 0 332m 71m 66m S 6 0.9 1:17.05 qemu-kvm
14954 root 20 0 14552 1072 812 R 0 0.0 0:00.01 top
1 root 20 0 10320 680 572 S 0 0.0 0:02.02 init

kvm_stat (snapshot):

kvm statistics

exits 12254399 79079
halt_exits 326543 4632
invlpg 0 0
io_exits 6539798 74320
irq_exits 43523 29
irq_window 4984 0
mmio_exits 1319016 0
pf_fixed 3140955 56
pf_guest 448187 6
request_irq 0 0
signal_exit 39728 0
tlb_flush 29511 31

when logging into the virtual machine (via ssh) the virtual world is
very slow: i set the time with "ntpdate" and wait exact one minute in
reality. in the virtual image only 24sec are gone!

and everything else in the image is really slow.

Avi Kivity schrieb:
> Ulrich Schreiner wrote:
>> hi,
>>
>> im using a 64 bit fedora7 system with a quad-core processor to host
>> multiple virtual machines.
>>
>> my current kernel is:
>>
>> Linux testserver 2.6.22.1-27.fc7 #1 SMP Tue Jul 17 17:19:58 EDT 2007
>> x86_64 x86_64 x86_64 GNU/Linux
>>
>> (now there is a 2.6.22.1-33.fc7 to download, but i think it is not the
>> point here).
>>
>> i installed
>>
>> kvm.x86_64: 31-1.fc8
>>
>> because of a crash i reported as a bug with the older kvm module.
>>
>> this system starts a F7 image with the following command:
>>
>> /usr/bin/qemu-kvm -net nic,macadr=52.54.00.12.34.57 -net
>> tap,script=./ifup.py,ifname=tap0
>> -hda /var/qemu/vm_images/F7image.img -boot c: -m 512 -vnc :2 -k de
>>
>> inside the image there is fedora 7, but a 32bit system.
>>
>> almost everything works (reboot hangs), but the system is extremely
>> slow! the clock inside the system is extremely slow: every *virtual*
>> second in the image is about two or more seconds in the *real* world.
>>
>
> Is there anything in dmesg? What does 'top' report? What does kvm_stat
> show?