Re: kvm very slow

Ulrich Schreiner
2007-08-07T12:50:22Z

> We're experiencing guest clock drifts even when the host is running with HZ=1000.
> But so far there were no performance problmes around it.
> It's worth a shot anyway.
>

are there any benchmarkings (and tools) which i can run inside the
guest? are there any official results with which i can compare?

my "performance problem" is that i have an image with an
applicationserver (python based) inside and this server performs better
(faster response times, more request/sec) when run with qemu/kqemu on my
1-year-old-sonynotebook (32-bit fedora7) compared to a quadcore 2month
old dell-server (64-bit fedora7) and qemu/kvm :-).

well ... it works, but it is a little disappointing.

the wrong timer is really awkward, because the time in the guest drifts
extremly (about half of real time) so the "ntpd" does not automatically
set update time because after some time the drift is so big, that ntpd
will not set the system time. i had to disable ntpd and start a cronjob
every minute to set the current time! so i only loose every second
minute.

my timestamps in the database for my webapp are ... well mostly ok. but
i cannot use this scenario for a productive system of my webapp.

i don't know if this behaviour (rtc/hpe) has impact on the performance
(hopefully, because you wrote work in on the way).