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Re: [fedora-virt] how can i verify that HW extensions are being used?



Eduardo Habkost wrote:
On Thu, Apr 16, 2009 at 07:48:52AM -0400, Robert P. J. Day wrote:
  apparently, i made one lame-brained move yesterday that almost
certainly caused my VM to run thigh-suckingly slowly.  following the
linux KVM FAQ, i wanted to configure KVM so i could run it as a
non-root user.  to that end, i

  * created a "kvm" group,
  * added my user account to the kvm group, and
  * added the rules file /etc/udev/rules.d/60-kvm.rules:

    KERNEL=="kvm", GROUP="kvm"

  i re-initialized udev with:

  # udevadm control --reload-rules   (right?)

unloaded my kvm modules (kvm and kvm_amd), reloaded them and, sure
enough, my new /dev/kvm device file had a group affiliation of kvm.
excellent, i thought, and away i went ... with still painfully slow
performance, until i realized that i was still in my original desktop
session which *wasn't* considered part of the kvm group.  so a quick
logout, log back in and things were much better.

  *that's* the sort of thing i'm trying to document as i write all of
this up -- those slight oversights which no one bothers to mention
that eventually bite you in the butt.  in any event, back to my
original question -- what could i have checked that would have told
me, no, you are *not* taking advantage of the AMD-V HW virt
extensions?  after all, my modules were loaded, /dev/kvm existed, it
clearly had the right group, but (and correct me if i'm wrong) i was
obviously not getting the benefit of HVM because my desktop session
wasn't considered part of the "kvm" group.

If you are using qemu directly, go to the monitor (ctrl-alt-f2) and type
"info kvm", and you can be sure if kvm is being used or not.

But you shouldn't be using qemu directly and use libvirt/virt-manager
instead. ;) However, I don't know what is the right command to check if
kvm is actually being used for a libvirt-managed guest.

Actually, that's one of the reasons I usually don't use a VMM, is just because I want to be able to get to KVM. And I have had far better luck using SVN for console than VNC, another minor issue.

--
bill davidsen <davidsen tmr com>
 CTO TMR Associates, Inc

"You are disgraced professional losers. And by the way, give us our money back."
   - Representative Earl Pomeroy,  Democrat of North Dakota
on the A.I.G. executives who were paid bonuses  after a federal bailout.



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