Re: kvm very slow

Dor Laor
2007-08-07T11:51:48Z

>today morning i compiled kvm-33 and the output of kvm-stat is much
>better now (guest in idle):
>
>kvm statistics
>
> efer_reload 10944273 6504
> exits 13722688 6967
> halt_exits 1084344 935
> invlpg 0 0
> io_exits 7668914 5070
> irq_exits 27886 2
> irq_window 11477 1
> light_exits 2778416 462
> mmio_exits 2153709 498
> pf_fixed 1085923 0
> pf_guest 459144 0
> request_irq 0 0
> signal_exit 25818 0
> tlb_flush 228295 5

It's much better. What does the guest do? It's weird it reloads the
efer.

>
>
>i don't know if these numbers are ok; do you still need the generated
>qemu.log for ioport access? if you need it i will upload it to my
public
>server.
>
>but: the system is slow. it is extremely slow when booting and the
>guest-system clock ist twice as slow as the host-system clock (both are
>idle; ok, the host as a runnung qemu-instance :-).
>
>when starting i get:
>
>Could not configure '/dev/rtc' to have a 1024 Hz timer. This is not a
>fatal
>error, but for better emulation accuracy either use a 2.6 host Linux
>kernel or
>type 'echo 1024 > /proc/sys/dev/rtc/max-user-freq' as root.
>
>well i HAVE a 2.6kernel (2.6.22.1-41.fc7), but i cannot set
>dev.rtc.max-user-freq, i only can set the high precision event timer
>
>dev.hpet.max-user-freq = 1024
>
>which i have done. but the message always appears. i don't know if this
>is ignorable.
>

The problem is that qemu calculates time using either sigalarm or rtc.
(the later in more accurate)
Seems like qemu doesn't get enough signals to inject timer irq to the
guest.

Luca claims the HPET intefer the RTC. Can it be disabled? ( I know some
new chipsets implement rtc using HPET).