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SubjectRe: [RFC/HACK] x86: Fast return to kernel

* Andy Lutomirski <luto@amacapital.net> wrote:

> > That said, regular *device* interrupts do often return to kernel
> > mode (the idle loop in particular), so if you have any way to
> > measure that, that might be interesting, and might show some of
> > the same advantages.
>
> I can try something awful involving measuring latency of
> hardware-timed packets on a SolarFlare card, but I'll have
> calibration issues. I suppose I could see if 'ping' gets faster.
> In general, this will speed up interrupts that wake userspace from
> idle by about 100ns on my box, since it's presumably the same size
> and the speedup per loop in my silly benchmark.

To simulate high rate device IRQ you can generate very high frequency
lapic IRQs by using hrtimers, that's generating a ton of per CPU lapic
IRQs.

Thanks,

Ingo


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