Re: [PATCH][RFC] per isr in_progress markers

From: Ingo Molnar (mingo@elte.hu)
Date: Mon Sep 09 2002 - 13:44:25 EST


On Mon, 9 Sep 2002, Linus Torvalds wrote:

> Remember: you'd be "improving latency" by taking several interrupts
> instead of taking just one. And usually, if the system is really under
> so much interrupt load that this would be noticeable, you want to try to
> _mitigate_ interrupts instead of adding new ones.

There's also the following effect that could generate additional
interrupts: the *same* IRQ source that is currently executing might
generate a (spurious but otherwise harmless) interrupt if we first ACK the
card then ACK the APIC and then do processing. Our current way of masking
interrupts in the IO-APIC at least leaves them pending there until the
handler's main work loop is finished and mitigates irqs.

        Ingo

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/



This archive was generated by hypermail 2b29 : Sun Sep 15 2002 - 22:00:17 EST