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SubjectRe: [PATCH][RFC] per isr in_progress markers
On Mon, 9 Sep 2002 21:37:42 +0200 (SAST)
Zwane Mwaikambo <zwane@mwaikambo.name> wrote:

> > (Btw, if there is, that would also allow us to notice the "constantly
> > screaming PCI interrupt" without help from the low-level isrs)
>
> As an aside, i just had an idea for another way to improve interrupt
> handling latency. Instead of walking through all the isrs in the chain,
> we can have an isr flag wether it was the source of the irq, and if so we
> stop right there and not walk through the other isrs. Obviously taking
> into account that some devices are dumb and have no real way of
> determining.
>
> Zwane

Hello,

a short note on that: this proved to be a particularly bad idea back in the
amiga-days. All that happened with this idea (Amiga which has basically only 2
usable interrupts has heavy interrupt sharing) is that every good programmer
told the system that it was not the source of the ongoing interrupt - even if
it was - because otherwise you lost interrupts in heavy-load environment.
Shared interrupts _can_ work well, but you have to do short interrupt-routines
and don't mess the thing by over-intelligent (in fact non-atomic) operation.

Regards,
Stephan


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