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[Xen-devel] Re: VT-d scalability issue

To: "Zhai, Edwin" <edwin.zhai@xxxxxxxxx>
Subject: [Xen-devel] Re: VT-d scalability issue
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 09 Sep 2008 11:22:15 +0100
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On 9/9/08 10:04, "Zhai, Edwin" <edwin.zhai@xxxxxxxxx> wrote:

> following code in vmx_do_resume try to invalidate orig processor's cache when
> 14 migration if this domain has pass-through device and no support for wbinvd
> vmexit.          
> 16 if ( has_arch_pdevs(v->domain) && !cpu_has_wbinvd_exiting )
> {
>     int cpu = v->arch.hvm_vmx.active_cpu;
>     if ( cpu != -1 )
>         on_selected_cpus(cpumask_of_cpu(cpu), wbinvd_ipi, NULL, 1,
> }
> So we want to pin vcpu to free processor for domains with pass-through device
> in
> creation process, just like what we did for NUMA system.

(a) pinning support already exists.Maybe list this as 'best practice' but I
don't see any need for xend changes, for example.
(b) presumably your upcoming (and existing current?) processors support
wbinvd exiting anyway?

 -- Keir

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