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

[Jan Kiszka]

Blue Swirl wrote:
>>>> This is - according to my current understanding - the proposed
>>>> alternative architecture:
>>>>
>>>>                                          .---------------.
>>>>                                          | de-coalescing |
>>>>                                          |     logic     |
>>>>                                          '---------------'
>>>>                                                ^   |
>>>>                                         period,|   |IRQ
>>>>                                       coalesced|   |(or tuned VM clock)
>>>>                                        (yes/no)|   v
>>>> .-------.              .--------.             .-------.
>>>> |  RTC  |-----IRQ----->| router |-----IRQ---->| APIC  |
>>>> '-------'              '--------'             '-------'
>>>>    |                    ^    |                   ^
>>>>    |                    |    |                   |
>>>>    '-------period-------'    '------period-------'
>>> The period information is already known by the higher level clock
>>> management,
>> The timer device models program the next event of some qemu-timer. There
>> is no tag attached explaining the timer subsystem or anyone else the
>> reason behind this programming.
> 
> Yes, but why would we care? All timers in the system besides RTC
> should be affected likewise, this would in fact be the benefit from
> handling the problem at higher level.

And how does your equation for calculating the clock slow-down look like?

Jan

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