[Xen-devel] Re: [GIT PULL] Xen APIC hooks (with io_apic_ops)

[Avi Kivity <avi@xxxxxxxxxx>]

Ingo Molnar wrote:
> > We do something similar for Windows (by patching it) very 
> > successfully; Windows likes to touch the APIC TPR ~ 100,000 times 
> > per second, usually without triggering an interrupt.  We hijack 
> > these writes, do the checks in guest context, and only exit if the 
> > TPR write would trigger an interrupt.
> >     
> I suspect you aware of that this is about the io-apic not the local 
> APIC. The local apic methods are already driver-ized - and they sit 
> closer to the CPU so they matter more to performance.
>   
Yeah, I gave this as an example.  It's very different -- io-apic vs. 
local apic, paravirtualization vs. patching the guest behind its back, 
Linux vs. Windows.
Of course if we hook the io-apic EOI we'll want to hook the local apic 
EOI as well.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.


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