Re: [Xen-devel] Windows SMP

["Andrew Lyon" <andrew.lyon@xxxxxxxxx>]

On Tue, Dec 30, 2008 at 2:41 PM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:
> On 30/12/2008 12:41, "Andrew Lyon" <andrew.lyon@xxxxxxxxx> wrote:
>
>>> In the architecture manual it is known as apic-access virtualisation. I
>>> don't know whether it would be a headline feature in a processor's data
>>> sheet.
>>
>> Can you point me to the code where apic-access virtualisation is used?
>> Displaying a message might be a nice small improvement for me to
>> figure out and contribute.
>
> You can make use of the macro cpu_has_vmx_virtualize_apic_accesses to
> control a printk() at the end of
> xen/arch/x86/hvm/vmx/vmcs.c:vmx_init_vmcs_config().
>

Thanks Keir, I added a couple of printk's as you suggested and I can
now see if the feature is supported:

Intel(R) Xeon(R) CPU           E5420  @ 2.50GHz = (XEN) APIC Access virtualized
Intel(R) Core(TM)2 CPU          6600  @ 2.40GHz = (XEN) APIC Access emulated

I didnt expect my Xeon system to support it, I've read some pdf's
about Intel virtualizaton features and they seemed to suggest it was a
new feature on 7xxx Xeons.

The results fit the performance I've seen, a windows xp 32 bit hvm
with 2 cpu's runs a lot faster on the Xeon 2.5 than on the Core 2.4.

Andy


>  -- Keir
>
>
>

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