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Bug 732811 - Enable hyper-v enlightenment features for windows VMs
Enable hyper-v enlightenment features for windows VMs
Status: RESOLVED OBSOLETE
Product: gnome-boxes
Classification: Applications
Component: windows
unspecified
Other Linux
: Normal normal
: --
Assigned To: GNOME Boxes maintainer(s)
GNOME Boxes maintainer(s)
: 750090 (view as bug list)
Depends on:
Blocks:
 
 
Reported: 2014-07-06 20:59 UTC by Cole Robinson
Modified: 2018-01-11 10:09 UTC
See Also:
GNOME target: ---
GNOME version: ---



Description Cole Robinson 2014-07-06 20:59:21 UTC
hyper-v enlightenments are paravirt optimizations that Windows VMs will use when they detect they are running on hyper-v. These bits add performance improvements Some of these optimizations can also be turned on with KVM. Some more info:

http://www.linux-kvm.org/wiki/images/0/0a/2012-forum-kvm_hyperv.pdf

After some off-list discussion with the KVM devs, here's the recommended configuration. Suggest to enable it for Windows VMs only. All Windows VMs is easiest and should be safe, but the only versions which start to support these bits are Vista+ and Server 2008+

The recommended qemu configuration is:

   -cpu ...,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time

Which maps to the libvirt XML:

   <features>
     <hyperv>
       <relaxed state='on'/>
       <vapic state='on'/>
       <spinlocks state='on' retries='8191'/>
     </hyperv>
   <features/>

   <clock ...>
     <timer name='hypervclock' present='yes'/>
   </clock>

Though there are some version caveats here:
- relaxed state='on' libvirt 1.0.0+, qemu 1.1+
- vapic, spinlocks requires libvirt 1.1.0+, qemu 1.1+
- hypervclock requires libvirt 1.2.2+, qemu 2.0.0+

AFAIK it should be safe to mix the hypervclock setting the other recommended timer settings (mentioned at https://bugzilla.redhat.com/show_bug.cgi?id=1053846 )
Comment 1 Zeeshan Ali 2014-07-08 18:33:16 UTC
I think this info should be coming through libosinfo. Could you please file a bug on that too.
Comment 2 Cole Robinson 2014-07-08 18:36:49 UTC
libosinfo bug: https://bugzilla.redhat.com/show_bug.cgi?id=1117465
Comment 3 Zeeshan Ali 2014-07-08 18:49:08 UTC
(In reply to comment #2)
> libosinfo bug: https://bugzilla.redhat.com/show_bug.cgi?id=1117465

Thanks
Comment 4 Zeeshan Ali 2015-05-29 11:37:22 UTC
*** Bug 750090 has been marked as a duplicate of this bug. ***
Comment 5 GNOME Infrastructure Team 2018-01-11 10:09:37 UTC
-- GitLab Migration Automatic Message --

This bug has been migrated to GNOME's GitLab instance and has been closed from further activity.

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