Re: [Xen-devel] [RFC PATCH 0/9] Introduce AMD SVM AVIC

[Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>]

Boris,

On 9/20/16 21:34, Boris Ostrovsky wrote:
> > BENCHMARK 1: HACKBENCH
> > > ======================
> > >
> > > For measuring IPI performance used for scheduling workload, I have collected
> > > some performance number on 2 and 3 CPU running hackbech with the following
> > > detail:
> > >
> > >   hackbench -p -l 100000
> > >   Running in process mode with 10 groups using 40 file descriptors each (== 
> > 400 tasks)
> > >   Each sender will pass 100000 messages of 100 bytes
> > >
> > >                        |  2 vcpus (sec) |  3 vcpus (sec)
> > >   --------------------------------------------------------
> > >     No AVIC w/o evtchn |     299.57     |    337.779
> > >     No AVIC w/  evtchn |     270.37     |    419.6064
> > >        AVIC w/  evtchn |     181.46     |    171.7957
> > >        AVIC w/o evtchn |     171.81     |    169.0858
> > >
> > > Note: In "w/o evtchn" case, the Linux guest is built w/o
> > >       Xen guest support.
> Enlightened Linux tries to avoid using event channels for APIC accesses
> if XEN_HVM_CPUID_APIC_ACCESS_VIRT or XEN_HVM_CPUID_X2APIC_VIRT is set.
>
> I didn't notice either of these two bits set in the series. Should they
> be (probably the first one)? Or is this something you are planning for
> the second part?
>
> -boris
Thanks for pointing this out. The XEN_HVM_CPUID_APIC_ACCESS_VIRT would 
likely be needed. Since it is related to MSI, this will be covered in 
the second part of this patch series.
Thanks,
Suravee

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