Re: [GIT PULL] AlacrityVM guest drivers for 2.6.33

Gleb Natapov
2009-12-22T07:22:13Z

On Mon, Dec 21, 2009 at 12:44:17PM -0500, Gregory Haskins wrote:
> > They should be relatively rare
> > because obtaining good receive batching is pretty easy.
>
> Batching is poor mans throughput (its easy when you dont care about
> latency), so we generally avoid as much as possible.
>
> > Considering
> > these are lightweight exits (on the order of 1-2us),
>
> APIC EOIs on x86 are MMIO based, so they are generally much heavier than
> that. I measure at least 4-5us just for the MMIO exit on my Woodcrest,
> never mind executing the locking/apic-emulation code.
>
With x2apic EOIs are not MMIO any longer.

--
Gleb.