Re: [libvirt] virt-top version bump in EPEL5
On Mon, Sep 06, 2010 at 05:46:03PM +0200, Wolfram Schlich wrote:
* Richard W.M. Jones <rjones(a)redhat.com> [2010-09-06 17:23]:
> On Mon, Sep 06, 2010 at 05:06:55PM +0200, Wolfram Schlich wrote:
> > We are experiencing a problem with virt-top on our RHEL5 virthosts.
> >
> > On a heavily loaded virthost, virt-top is damn slow -- it takes 4-5s
> > to update and imposes a noticeable load on the dom0 as well
> > (xenstored shows up in top eating all CPU for some seconds).
> > xentop seems to impose *much* less load on the dom0.
> > Is there something I can do about it?
> >
> > Another problem: 0.3.3.1 shows RDRQ/WRRQ/RXBY/TXBY after some seconds
> > whereas 1.0.4 does not...?
>
> I bet both of these will be libvirt issues.
>
> Try running:
>
> virsh list --all
Takes around 2-4s depending on dom0 load.
CC-ing to libvir-list. There may be a better way now for virt-top to
get the list of domains, but if 'virsh list --all' is also slow, then
it's probably a generic libvirt problem.
> virsh domblkstat DomainName hda
s/hda/xvda/ I guess :)
This one is quite fast, below 0.2s.
> virsh domifstat DomainName vnet0
This takes around 0.1s most of the time, but sometimes around 1.0s.
> etc.
>
> If those commands (done in a suitable loop) also cause load on the
> dom0, and if domblkstat/domifstat don't show stats, then it's down to
> libvirt.
>
> virt-top is a simple little program that just exercises those libvirt
> APIs ...
Hmm :/ So I guess we're better off with xentop...
We should be able to have performance very close to xentop. After
all, libvirt makes exactly the same direct hypervisor calls.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming blog: http://rwmj.wordpress.com
Fedora now supports 80 OCaml packages (the OPEN alternative to F#)
http://cocan.org/getting_started_with_ocaml_on_red_hat_and_fedora