[libvirt] [PATCH 1/1] cpu_map.xml: add cmt/mbm feature to x86

[Daniel P. Berrange]

On Fri, Jun 17, 2016 at 11:17:47AM +0200, Jiri Denemark wrote:
> On Fri, Jun 17, 2016 at 09:25:14 +0200, Jiri Denemark wrote:
> > On Fri, Jun 17, 2016 at 09:23:56 +0800, Qiaowei Ren wrote:
> > > Some Intel processor families (e.g. the Intel Xeon processor E5 v3
> > > family) introduced some PQos (Platform Qos) features, including CMT
> > > (Cache Monitoring echnology) and MBM (Memory Bandwidth Monitoring),
> > > to monitor or control shared resource. This patch add them into x86
> > > part of cpu_map.xml to be used for applications (like OpenStack)
> > > based on libvirt to get cpu capabilities.
> > > 
> > > Signed-off-by: Qiaowei Ren <qiaowei.ren at intel.com>
> > > ---
> > >  src/cpu/cpu_map.xml | 11 +++++++++++
> > >  1 file changed, 11 insertions(+)
> > > 
> > > diff --git a/src/cpu/cpu_map.xml b/src/cpu/cpu_map.xml
> > > index 08aded2..2e2cb4f 100644
> > > --- a/src/cpu/cpu_map.xml
> > > +++ b/src/cpu/cpu_map.xml
> > > @@ -320,6 +320,9 @@
> > >      <feature name='rtm'>
> > >        <cpuid function='0x00000007' ebx='0x00000800'/>
> > >      </feature>
> > > +    <feature name='cmt'>
> > > +      <cpuid function='0x00000007' ebx='0x00001000'/>
> > > +    </feature>
> > >      <feature name='mpx'>
> > >        <cpuid function='0x00000007' ebx='0x00004000'/>
> > >      </feature>
> > 
> > This hunk won't apply since about a week ago. Please, use current git
> > when sending patches.
> > 
> > > @@ -353,6 +356,14 @@
> > >        <cpuid function='0x80000007' edx='0x00000100'/>
> > >      </feature>
> > >  
> > > +    <!-- cpuid level 0x0000000f:1 (edx) -->
> > > +    <feature name='mbm_total'> <!-- LLC Total MBM monitoring -->
> > > +      <cpuid function='0x0000000f' edx='0x00000002'/>
> > > +    </feature>
> > > +    <feature name='mbm_local'> <!-- LLC Local MBM monitoring -->
> > > +      <cpuid function='0x0000000f' edx='0x00000004'/>
> > > +    </feature>
> > > +
> > 
> > And keep the list of features sorted by CPUID level, i.e., these
> > features should go after 0x0d and before 0x80000000.
> 
> Oh and I completely forgot the most important thing: it makes little
> sense to add CPUID features that QEMU does not support. It will only
> allow users to see the features in host CPU capabilities. So if the
> purpose of these patches is to be able to advertise whether the
> appropriate perf events are supported on current host, CPU features are
> not the right way of doing that. I think domain capabilities XML would
> be the right place to advertise what events are supported.

Nova schedules guests based on the CPU features that the host has, so
we really do want this to be exposed in the general host capabilities
XML description of the host CPU. We don't care about running guests
with this features - we just want to see the host report for them.


Regards,
Daniel
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