Re: [PATCH RFC] kvm: add PV MMIO EVENTFD

[Gleb Natapov]

On Thu, Apr 04, 2013 at 05:36:40PM +0200, Alexander Graf wrote:
> > 
> > #define GOAL (1ull << 30)
> > 
> >        do {
> >                iterations *= 2;
> >                t1 = rdtsc();
> > 
> >                        for (i = 0; i < iterations; ++i)
> >                                func();
> >                t2 = rdtsc();
> >        } while ((t2 - t1) < GOAL);
> >        printf("%s %d\n", test->name, (int)((t2 - t1) / iterations));
> 
> So it's the number of cycles per run.
> 
> That means translated my numbers are:
> 
>   MMIO: 4307
>   PIO: 3658
>   HCALL: 1756
> 
> MMIO - PIO = 649
> 
> which aligns roughly with your PV MMIO callback.
> 
> My MMIO benchmark was to poke the LAPIC version register. That does go through instruction emulation, no?
> 
It should and PIO 'in' or string also goes through the emulator.

--
			Gleb.
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