Re: kvm very slow

Avi Kivity
2007-08-02T08:24:37Z

Ulrich Schreiner wrote:
> dmesg|grep kvm
>
> SELinux: initialized (dev kvmfs, type kvmfs), uses genfs_contexts
> kvm: emulating exchange as write
>
>

There may be messages that aren't prefixed with 'kvm:' (that's a bug
btw). Please check.

> 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
>

Wow -- lots of I/O exits. What does 'top' in the guest say? 'hdparm
/dev/hda' in the guest?

> 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.
>
>

--
error compiling committee.c: too many arguments to function