Re: [Qemu-devel] Re: [RFT][PATCH 07/15] qemu_irq: Add IRQ handlers with delivery feedback

[Avi Kivity]

On 05/29/2010 12:15 PM, Blue Swirl wrote:
> > > This would allow counting the executed instructions and limit it. Thus
> > > we could emulate a 500MHz CPU on a 2GHz CPU more accurately.
> > >
> > >        
> > Why would you want to limit number of instruction executed by guest if
> > CPU has nothing else to do anyway? The problem occurs not when we have
> > spare cycles so give to a guest, but in opposite case.
> >      
> I think one problem is that the guest has executed too much compared
> to what would happen with real HW with a lesser CPU. That explains the
> RTC frequency reprogramming case.
>    

The root cause is that while qemu is scheduled out, the real time clock 
keeps ticking.  Since we can't stop real time, we must compensate in 
other ways.

> > So write the code and show us. You haven't show any evidence that RTC is
> > the wrong place. RTC knows when interrupt was acknowledge to RTC, it
> > know when clock frequency changes, it know when device reset happened.
> > APIC knows only that interrupt was coalesced. It doesn't even know that
> > it may be masked by a guest in IOAPIC (interrupts delivered while they
> > are masked not considered coalesced).
> >      
> Oh, I thought interrupt masking was the reason for coalescing! What
> exactly is the reason then?
>    

The above.

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error compiling committee.c: too many arguments to function