On Mon, Dec 14, 2009 at 02:02:03PM -0600, Anthony Liguori wrote:
> Gleb Natapov wrote:
> >>I thought KVM emulates the syscall instruction? I swear I've seen
> >>patches for that.
> >>
> >It is. Starting from 2.6.32.
>
> Okay, so this is a performance vs. migration compatibility issue then?
>
> BTW, couldn't we just not advertise syscall in cpuid? That should
> fix it too without sacrificing migration compatibility. We get a
> slight slowdown on AMD hosts but that's probably minor compared to
> the cost of using emulated syscall on Intel hosts.
>
As far as I understand not advertising syscall for 64bit CPU is not a
valid option.
--
Gleb.
