Re: [Qemu-devel] QEMU/MIPS & dyntick kernel

[Avi Kivity <avi@qumranet.com>]

Aurelien Jarno wrote:
> Hi,
>
> As announced by Ralf Baechle, dyntick is now available on MIPS. I gave a
> try on QEMU/MIPS, and unfortunately it doesn't work correctly.
>
> In some cases the kernel schedules an event very near in the future, 
> which means the timer is scheduled a few cycles only from its current
> value. Unfortunately under QEMU, the timer runs too fast compared to the
> speed at which instructions are execution.
Sounds like a kernel bug.  Can't there conceivably exist real hardware 
(or a real timeout) that exhibits the same timing?
Especially today with variable clock frequencies, I don't see how the 
kernel can rely on exact timing.
--
Any sufficiently difficult bug is indistinguishable from a feature.