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Date:   Mon, 20 Feb 2017 14:23:20 -0800
To:     Paolo Bonzini <>,
        Andy Lutomirski <>
CC:     kvm list <>,,
        X86 ML <>, Borislav Petkov <>
Subject: Re: RFC: Getting rid of LTR in VMX

On February 20, 2017 2:02:53 PM PST, Paolo Bonzini <> wrote:
>> > Yes.  But 150-200 clock cycles are nothing compared to the cache
>> > you get from preemption, so I'd ignore that.  Saving 300 clock
>cycles on
>> > userspace exits from TR+GSBASE would be about 5% on my Haswell.
>> That's still 5% :)
>Yes, 5% on userspace exits is good (though they're rare).
>OTOH, 300 clock cycles on preemption are nothing to write home about.

Oh, I would say it is... especially when it's basically free.
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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